Topic Editors

Department of Engineering and Materials Science and Transport, University of Seville (US), 41004 Seville, Spain
Department of Engineering and Materials Science and Transport, University of Seville (US), 41004 Seville, Spain
Department of Chemical Engineering, Escuela Politécnica Superior, Universidad de Sevilla, 41011 Sevilla, Spain

Scientific Advances in STEM: Synergies to Achieve Success, 3rd Volume

Abstract submission deadline
closed (31 May 2024)
Manuscript submission deadline
closed (31 July 2024)
Viewed by
18633

Topic Information

Dear Colleagues,

Following the previous special topics (scientific advances in STEM: from professors to students, 1st and 2nd editions), this new topic tries to highlight the importance of establishing synergies between research groups from different disciplines, combining the scientific knowledge from basic to applied research, as well as taking advantage of different research facilities. Fundamental science helps to understand the phenomenological basics, while applied science focuses on products and technology developments, highlighting the need to transfer knowledge to society and industrial sectors. This topic integrates interdisciplinary research of science and technology, including, but not limited to the following topics: 

  • Science and technology of materials 
  • Physics and applied mathematics 
  • Industrial and environmental chemistry 
  • Analytic chemistry 
  • Intelligent systems and electronic technology 
  • Product design, development, and engineering 
  • Computerized, robotic, and neuromorphic industrial systems 
  • Computer architecture and technology Particular Themes
  • Coatings and nanostructured materials 
  • Development of functional materials for additive manufacturing (i.e., applications in biomedicine) 
  • Advanced optical characterization or nano- and microstructures and thin films 
  • Biopolymer from agro-food bioresidues 
  • Interfacial rheology and its applications 
  • Deep-learning systems for diagnosis, prevention, and pattern recognition 
  • Bio-inspired systems for sensory fusion and control 
  • Artificial intelligence in smart-city applications 
  • Energy forecasting and flexibility services 
  • Advances in food and by-product development and characterization 
  • New trends in sustainable cities and industries 
  • Intelligent and sustainable optimization of industrial engineering projects 
  • Multifunctional and smart toys for children with autism spectrum disorder 
  • Weighting with life cycle assessment and cradle-to-cradle (methodology for global sustainability design social and socio-economic life cycle assessment: towards quantitative methods in small and medium-sized enterprises) 
  • Analysis of emerging pollutants in environmental samples 
  • Biomechanical and biofunctional behaviour of porous materials
Prof. Dr. Yadir Torres Hernández
Dr. Ana María Beltrán Custodio
Dr. Manuel Félix Ángel
Topic Editors

Keywords

  • solar energy applications
  • additive manufacturing
  • superficial modification
  • functional materials
  • tribo-mechanical behaviour
  • bio residues, biopolymer
  • computer architecture
  • artificial intelligence
  • smart cities
  • food
  • sustainable cities and industries
  • life cycle assessment
  • emerging pollutants
  • cellular and bacterial behaviour
  • powder technology

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Foods
foods
4.7 7.4 2012 14.3 Days CHF 2900
Materials
materials
3.1 5.8 2008 15.5 Days CHF 2600
Polymers
polymers
4.7 8.0 2009 14.5 Days CHF 2700
Sensors
sensors
3.4 7.3 2001 16.8 Days CHF 2600
Applied Sciences
applsci
2.5 5.3 2011 17.8 Days CHF 2400

Preprints.org is a multidiscipline platform providing preprint service that is dedicated to sharing your research from the start and empowering your research journey.

MDPI Topics is cooperating with Preprints.org and has built a direct connection between MDPI journals and Preprints.org. Authors are encouraged to enjoy the benefits by posting a preprint at Preprints.org prior to publication:

  1. Immediately share your ideas ahead of publication and establish your research priority;
  2. Protect your idea from being stolen with this time-stamped preprint article;
  3. Enhance the exposure and impact of your research;
  4. Receive feedback from your peers in advance;
  5. Have it indexed in Web of Science (Preprint Citation Index), Google Scholar, Crossref, SHARE, PrePubMed, Scilit and Europe PMC.

Published Papers (13 papers)

Order results
Result details
Journals
Select all
Export citation of selected articles as:
14 pages, 1842 KiB  
Article
Prediction of Flotation Deinking Performance: A Comparative Analysis of Machine Learning Techniques
by Tamara Gavrilović, Vladimir Despotović, Madalina-Ileana Zot and Maja S. Trumić
Appl. Sci. 2024, 14(19), 8990; https://doi.org/10.3390/app14198990 - 6 Oct 2024
Viewed by 673
Abstract
Flotation deinking is one of the most widely used techniques for the separation of ink particles from cellulose fibers during the process of paper recycling. It is a complex process influenced by a variety of factors, and is difficult to represent and usually [...] Read more.
Flotation deinking is one of the most widely used techniques for the separation of ink particles from cellulose fibers during the process of paper recycling. It is a complex process influenced by a variety of factors, and is difficult to represent and usually results in models that are inconvenient to implement and/or interpret. In this paper, a comprehensive study of several machine learning methods for the prediction of flotation deinking performance is carried out, including support vector regression, regression tree ensembles (random forests and boosting) and Gaussian process regression. The prediction relies on the development of a limited dataset that assumes representative data samples obtained under a variety of laboratory conditions, including different reagents, pH values and flotation residence times. The results obtained in this paper confirm that the machine learning methods enable the accurate prediction of flotation deinking performance even when the dataset used for training the model is limited, thus enabling the determination of optimal conditions for the paper recycling process, with only minimal costs and effort. Considering the low complexity of the Gaussian process regression compared to the aforementioned ensemble models, it should be emphasized that the Gaussian process regression gave the best performance in estimating fiber recovery (R2 = 97.77%) and a reasonable performance in estimating the toner recovery (R2 = 86.31%). Full article
Show Figures

Figure 1

15 pages, 3731 KiB  
Article
Multi-Objective Optimization of Crashworthiness of Shrink Tube Energy Absorption Structure
by Fan Zou and Shuguang Yao
Appl. Sci. 2024, 14(16), 7347; https://doi.org/10.3390/app14167347 - 20 Aug 2024
Viewed by 687
Abstract
By means of material testing, truck testing and numerical simulation, the structural parameters of the shrink tube anti-climb device for high-speed trains were determined. The effects of cone angle, tube thickness, friction coefficient and axial length of the friction cone on the crashworthiness [...] Read more.
By means of material testing, truck testing and numerical simulation, the structural parameters of the shrink tube anti-climb device for high-speed trains were determined. The effects of cone angle, tube thickness, friction coefficient and axial length of the friction cone on the crashworthiness of the shrink tube were studied, and the main causes were analyzed. Using cone angle and tube wall thickness as input variables, and peak crush force, mean crash force and specific energy absorption as crashworthiness indexes, a proxy model was constructed using a radial basis function. The global response surface methodology was adopted to optimize the design of the shrink tube’s structural parameters. The results showed that the crashworthiness of the shrink tube was positively correlated with the cone angle, the thickness of the shrink tube and the friction coefficient, and the influence decreased successively, while the influence was negatively correlated with the axial length of the friction cone, which had the least influence. Through the optimized design, the peak force of the shrink tube increased by only 5.41%, while the specific energy absorption increased by 31.03%. Additionally, the mean force was closer to the technical requirements of 600 kN, and the crashworthiness was optimized. Full article
Show Figures

Figure 1

36 pages, 11422 KiB  
Article
Analysis and Experiment of Thermal Field Distribution and Thermal Deformation of Nut Rotary Ball Screw Transmission Mechanism
by Hanwen Yu, Xuecheng Luan, Guiyuan Zheng, Guangchao Hao, Yan Liu, Hongyu Xing, Yandong Liu, Xiaokui Fu and Zhi Liu
Appl. Sci. 2024, 14(13), 5790; https://doi.org/10.3390/app14135790 - 2 Jul 2024
Viewed by 982
Abstract
This study designs a differential dual-drive micro-feed mechanism, superposing the two “macro feed motions” (“motor drive screw” and “motor drive nut”) using the same transmission of “the nut rotary ball screw pair” structure. These two motions are almost equal in terms of speed [...] Read more.
This study designs a differential dual-drive micro-feed mechanism, superposing the two “macro feed motions” (“motor drive screw” and “motor drive nut”) using the same transmission of “the nut rotary ball screw pair” structure. These two motions are almost equal in terms of speed and turning direction, thus the “micro feed” can be obtained. (1) Background: Thermal deformation is the primary factor that can restrict the high-precision micro-feed mechanism and the distribution of heat sources differs from that of the conventional screw single-drive system owing to the structure and motion features of the transmission components. (2) Discussion: This study explores the thermal field distribution and thermal deformation of the differentially driven micro-feed mechanism when two driving motors are combined at different speeds. (3) Methods: Based on the theory of heat transfer, the differential dual-drive system can be used as the research object. The thermal equilibrium equations of the micro-feed transmission system are established using the thermal resistance network method, and a thermal field distribution model is obtained. (4) Results: Combined with the mechanism of thermal deformation theory, the established thermal field model is used to predict the axial thermal deformation of the differential dual-drive ball screw. (5) Conclusions: Under the dual-drive condition, the steady-state thermal error of the nut-rotating ball screw transmission mechanism increases with the increase in nut speed and composite speed and is greater than the steady-state thermal error under the single screw drive condition. After reaching the thermal steady state, the measured thermal elongation at the end of the screw in the experiment is approximately 10.5 μm and the simulation result is 11.98 μm. The experimental measurement result demonstrates the accuracy of the theoretical analysis model for thermal error at the end of the screw. Full article
Show Figures

Figure 1

18 pages, 9022 KiB  
Article
Influence of Materials of Moulds and Geometry of Specimens on Mechanical Properties of Grouts Based on Ultrafine Hydraulic Binder
by Beatriz Hortigon, Esperanza Rodriguez-Mayorga, Jose Antonio Santiago-Espinal, Fernando Ancio and Jose Maria Gallardo
Materials 2024, 17(7), 1645; https://doi.org/10.3390/ma17071645 - 3 Apr 2024
Cited by 1 | Viewed by 864
Abstract
Ultrafine hydraulic binder grout injection is a technique utilised for repairing masonry, either to connect sections, seal joints, or fill voids due to its great capacity for penetration and higher mechanical strength than lime grout. In this research, the mechanical properties of ultrafine [...] Read more.
Ultrafine hydraulic binder grout injection is a technique utilised for repairing masonry, either to connect sections, seal joints, or fill voids due to its great capacity for penetration and higher mechanical strength than lime grout. In this research, the mechanical properties of ultrafine hydraulic cement grout are analysed considering the influence of the mould material for preparing the specimens and their geometry characteristics in the context of the specifications set out in several international standards. The test campaign to ascertain compressive and flexural strength in different circumstances is supplemented with a physical and chemical characterisation of both binder and fresh and hardened grout. Significant differences in mechanical properties between specimens prepared with absorbent or non-absorbent-water material are found due to the influence of drying shrinkage and decanting binder during the curing process. Furthermore, the slenderness of specimens is presented as an important factor in determining the compressive strength of mixtures. Full article
Show Figures

Figure 1

14 pages, 10482 KiB  
Article
Effect of the Silanization of Aerosil OX50 in the Properties of Light-Cured Dental Composites
by Selena de la Caridad Díaz-Rodríguez, Oridayma Tarano-Artigas, Wilberth Herrera-Kao, Juan Valerio Cauich-Rodríguez, José Manuel Cervantes-Uc, Ana Rosa-Sainz, Amisel Almirall La Serna and Yaymarilis Veranes-Pantoja
Appl. Sci. 2024, 14(6), 2453; https://doi.org/10.3390/app14062453 - 14 Mar 2024
Cited by 1 | Viewed by 1307
Abstract
In this study, the surface of aerosil OX50 was treated with γ-methacryloxypropyltrimethoxysilane in order to evaluate its effect on light-cured dental composites. Four composites were prepared with Bis-GMA/tetraethylene glycol dimethacrylate/γ-methacryloxypropyltrimethoxysilane, Bis-GMA/tetraethylene glycol dimethacrylate, and a 45% treated or untreated aerosil OX50, using the [...] Read more.
In this study, the surface of aerosil OX50 was treated with γ-methacryloxypropyltrimethoxysilane in order to evaluate its effect on light-cured dental composites. Four composites were prepared with Bis-GMA/tetraethylene glycol dimethacrylate/γ-methacryloxypropyltrimethoxysilane, Bis-GMA/tetraethylene glycol dimethacrylate, and a 45% treated or untreated aerosil OX50, using the camphorquinone/N,N-dimethylaminoethyl methacrylate pair as initiator. Evidence of filler silanization was provided by FTIR as a low-intensity absorption at 1707 cm−1 (carbonyl functional group) while thermogravimetric analysis showed a mass loss of approximately 2% associated with the decomposition of γ-methacryloxypropyltrimethoxysilane. The experimental composites studied meet the requirements of the ISO 4049:2019 standard for depth of cure, water sorption, and solubility. The composites are shown to be thermally stable and presented a degree of conversion higher than 70%, being higher than that reported for many commercial composites. Based on the observed properties, the best formulations were those in which the silane is incorporated into the matrix and the filler was previously treated. Full article
Show Figures

Figure 1

15 pages, 4946 KiB  
Article
Feasibility of Invasive Brown Seaweed Rugulopteryx okamurae as Source of Alginate: Characterization of Products and Evaluation of Derived Gels
by Ismael Santana, Manuel Felix and Carlos Bengoechea
Polymers 2024, 16(5), 702; https://doi.org/10.3390/polym16050702 - 5 Mar 2024
Cited by 2 | Viewed by 1327
Abstract
Rugulopteryx okamurae (RO) is an invasive brown seaweed that causes severe environmental problems in the Mediterranean Sea. This work proposed an extraction method that enables their use as a raw material for producing sodium alginate. Alginate was successfully extracted from this invasive seaweed, [...] Read more.
Rugulopteryx okamurae (RO) is an invasive brown seaweed that causes severe environmental problems in the Mediterranean Sea. This work proposed an extraction method that enables their use as a raw material for producing sodium alginate. Alginate was successfully extracted from this invasive seaweed, with its gelling performance in the presence of Ca2+ ions comparable to existing commercial alginates. The mannuronic acid (M)-to-guluronic (G) acid ratio in the 1H-NMR profile indicated a higher percentage of G in the RO-extracted alginate, which implies a greater formation of so-called egg box structures. These differences resulted in their different rheological behaviour, as sodium alginate aqueous solutions exhibited a greater viscosity (η at 1 s−1 = 3.8 ± 0.052 Pa·s) than commercial alginate (2.8 ± 0.024 Pa·s), which is related to the egg box structure developed. When gelled in the presence of calcium, an increase in the value of the elastic modulus was observed. However, the value of the tan δ for the extracted alginate was lower than that of commercial alginate gels, confirming a structure more densely packed, which implies a different restructuring of the alginate chain when gelling. These results confirm the suitability of using invasive Rugulopteryx okamurae as a source of calcium alginate gels. In this way, sustainable bio-based materials may be produced from undesired biomass that currently poses a threat to the ecosystem. Full article
Show Figures

Figure 1

15 pages, 16171 KiB  
Article
Protecting FPGA-Based Cryptohardware Implementations from Fault Attacks Using ADCs
by Francisco Eugenio Potestad-Ordóñez, Alejandro Casado-Galán and Erica Tena-Sánchez
Sensors 2024, 24(5), 1598; https://doi.org/10.3390/s24051598 - 29 Feb 2024
Cited by 2 | Viewed by 1354
Abstract
The majority of data exchanged between connected devices are confidential and must be protected against unauthorized access. To ensure data protection, so-called cryptographic algorithms are used. These algorithms have proven to be mathematically secure against brute force due to the key length, but [...] Read more.
The majority of data exchanged between connected devices are confidential and must be protected against unauthorized access. To ensure data protection, so-called cryptographic algorithms are used. These algorithms have proven to be mathematically secure against brute force due to the key length, but their physical implementations are vulnerable against physical attacks. The physical implementation of these algorithms can result in the disclosure of information that can be used to access confidential data. Some of the most powerful hardware attacks presented in the literature are called fault injection attacks. These attacks involve introducing a malfunction into the normal operation of the device and then analyzing the data obtained by comparing them with the expected behavior. Some of the most common methods for injecting faults are the variation of the supply voltage and temperature or the injection of electromagnetic pulses. In this paper, a hardware design methodology using analog-to-digital converters (ADCs) is presented to detect attacks on cryptocircuits and prevent information leakage during fault injection attacks. To assess the effectiveness of the proposed design approach, FPGA-based ADC modules were designed that detect changes in temperature and supply voltage. Two setups were implemented to test the scheme against voltage and temperature variations and injections of electromagnetic pulses. The results obtained demonstrate that, in 100% of the cases, when the correct operating voltage and temperature range were established, the detectors could activate an alarm signal when the cryptographic module was attacked, thus avoiding confidential information leakage and protecting data from being exploited. Full article
Show Figures

Figure 1

13 pages, 1911 KiB  
Article
Chloride Permeability of Alkali-Activated Slag Concretes after Exposure to High Temperatures
by Baomeng Zhou, Qianmin Ma, Rongxin Guo and Ping Li
Materials 2024, 17(5), 1028; https://doi.org/10.3390/ma17051028 - 23 Feb 2024
Viewed by 861
Abstract
The number of fires in buildings and on bridges has increased worldwide in recent years. As a structural material, the strength of alkali-activated slag (AAS) concrete after exposure to high temperatures has been given much attention. However, research of its durability is still [...] Read more.
The number of fires in buildings and on bridges has increased worldwide in recent years. As a structural material, the strength of alkali-activated slag (AAS) concrete after exposure to high temperatures has been given much attention. However, research of its durability is still lacking, which limits the application of this type of concrete on a larger scale. In this context, as one of the most important aspects of durability, the chloride permeability of AAS concretes after exposure to high temperatures was examined in this study. The influence of the alkali concentration (Na2O%) and the modulus (Ms) of the activator, as well as the influence of heating regimes, including the heating rate, duration of exposure to the target temperature, and cooling method, was also discussed. The results show that the chloride permeability of the AAS concretes increased with temperature elevation. Due to the interference of pore solution conductivity, the influence of the Na2O% and the Ms of the activator on the chloride permeability of the AAS concretes was not made clear by using the ASTM C 1202 charge passed method; however, after exposure to high temperatures, AAS with a lower Na2O% and lower Ms has lower porosity and may have lower chloride permeability, which needs further investigation. Faster heating for a longer duration at the target temperature and water cooling reduced the resistance of the AAS concretes to chloride permeability as a result of their increased porosity. Full article
Show Figures

Figure 1

17 pages, 4497 KiB  
Article
Identification of Olives Using In-Field Hyperspectral Imaging with Lightweight Models
by Samuel Domínguez-Cid, Diego Francisco Larios, Julio Barbancho, Francisco Javier Molina, Javier Antonio Guerra and Carlos León
Sensors 2024, 24(5), 1370; https://doi.org/10.3390/s24051370 - 20 Feb 2024
Viewed by 1141
Abstract
During the growing season, olives progress through nine different phenological stages, starting with bud development and ending with senescence. During their lifespan, olives undergo changes in their external color and chemical properties. To tackle these properties, we used hyperspectral imaging during the growing [...] Read more.
During the growing season, olives progress through nine different phenological stages, starting with bud development and ending with senescence. During their lifespan, olives undergo changes in their external color and chemical properties. To tackle these properties, we used hyperspectral imaging during the growing season of the olives. The objective of this study was to develop a lightweight model capable of identifying olives in the hyperspectral images using their spectral information. To achieve this goal, we utilized the hyperspectral imaging of olives while they were still on the tree and conducted this process throughout the entire growing season directly in the field without artificial light sources. The images were taken on-site every week from 9:00 to 11:00 a.m. UTC to avoid light saturation and glitters. The data were analyzed using training and testing classifiers, including Decision Tree, Logistic Regression, Random Forest, and Support Vector Machine on labeled datasets. The Logistic Regression model showed the best balance between classification success rate, size, and inference time, achieving a 98% F1-score with less than 1 KB in parameters. A reduction in size was achieved by analyzing the wavelengths that were critical in the decision making, reducing the dimensionality of the hypercube. So, with this novel model, olives in a hyperspectral image can be identified during the season, providing data to enhance a farmer’s decision-making process through further automatic applications. Full article
Show Figures

Figure 1

18 pages, 4532 KiB  
Article
Development and Characterization of Edible Films Based on Cassava Starch Modified by Corona Treatment
by Carlos Mauricio Otálora González, Manuel Felix, Carlos Bengoechea, Silvia Flores and Lía Noemí Gerschenson
Foods 2024, 13(3), 468; https://doi.org/10.3390/foods13030468 - 2 Feb 2024
Cited by 4 | Viewed by 1589
Abstract
Corona treatment (CT), a surface treatment widely used in the plastic industry, can be used to alter the properties of cassava starch. In the present work, CT was performed on dry granular starch (DS), water-suspended humid granular starch (HS), and gelatinized starch (GS). [...] Read more.
Corona treatment (CT), a surface treatment widely used in the plastic industry, can be used to alter the properties of cassava starch. In the present work, CT was performed on dry granular starch (DS), water-suspended humid granular starch (HS), and gelatinized starch (GS). Different properties and structural characteristics of treated starches were studied. A lowering in pH was generally observed after CT and the rheological properties depended on the starch presentation. A reinforcement of DS and HS samples after CT was deduced from higher viscosity values in flow assays and viscoelastic moduli, but weak gels were obtained when CT was applied to GS. Changes in the A-type polymorphic structure, as well as a drop in relative crystallinity, were produced by CT for DS and HS. Additionally, changes in O-H and C-O-C FTIR bands were observed. Therefore, CT can be applied for starch modification, producing predominantly cross-linking in the DS and de-polymerization in the HS. Casting films made from the modified DS showed higher tensile strength and lower hydrophilicity, solubility, water absorption capacity, and water vapor permeability. Thus, the DS cross-linking induced by CT improved mechanical characteristics and hydrophobicity in edible films, which can be better used as packaging materials. Full article
Show Figures

Graphical abstract

21 pages, 10097 KiB  
Article
Assessing Formability and Failure of UHMWPE Sheets through SPIF: A Case Study in Medical Applications
by Ana Rosa-Sainz, M. Beatriz Silva, Ana M. Beltrán, Gabriel Centeno and Carpóforo Vallellano
Polymers 2023, 15(17), 3560; https://doi.org/10.3390/polym15173560 - 27 Aug 2023
Cited by 3 | Viewed by 1488
Abstract
This work presents a comprehensive investigation of an experimental study conducted on ultra-high molecular weight polyethylene (UHMWPE) sheets using single point incremental forming (SPIF). The analysis is performed within a previously established research framework to evaluate formability and failure characteristics, including necking and [...] Read more.
This work presents a comprehensive investigation of an experimental study conducted on ultra-high molecular weight polyethylene (UHMWPE) sheets using single point incremental forming (SPIF). The analysis is performed within a previously established research framework to evaluate formability and failure characteristics, including necking and fracture, in both conventional Nakajima tests and incremental sheet forming specimens. The experimental design of the SPIF tests incorporates process parameters such as spindle speed and step down to assess their impact on the formability of the material and the corresponding failure modes. The results indicate that a higher step down value has a positive effect on formability in the SPIF context. The study has identified the tool trajectory in SPIF as the primary influencing factor in the twisting failure mode. Implementing a bidirectional tool trajectory effectively reduced instances of twisting. Additionally, this work explores a medical case study that examines the manufacturing of a polyethylene liner device for a total hip replacement. This investigation critically analyses the manufacturing of plastic liner using SPIF, focusing on its formability and the elastic recovery exhibited by the material. Full article
Show Figures

Graphical abstract

17 pages, 26105 KiB  
Article
Mechanical Properties of Weld Lines in Injection-Molded Carbon Fiber-Reinforced Nylon (PA-CF) Composites
by Xianpeng Wang, Zuguo Bao, Donglin Gao, Shiyao Huang, Li Huang, Qiuren Chen, Hailong Zhao, Weijian Han and Yahong Xu
Polymers 2023, 15(11), 2476; https://doi.org/10.3390/polym15112476 - 27 May 2023
Cited by 2 | Viewed by 2143
Abstract
Weld lines are a common defect generated in injection molding, which apparently affects the performance of final products, but the available reports on carbon fiber-reinforced thermoplastics are still rather few. In this study, the effects of injection temperature, injection pressure, and fiber content [...] Read more.
Weld lines are a common defect generated in injection molding, which apparently affects the performance of final products, but the available reports on carbon fiber-reinforced thermoplastics are still rather few. In this study, the effects of injection temperature, injection pressure, and fiber content on the mechanical properties of weld lines were studied for carbon fiber-reinforced nylon (PA-CF) composites. The weld line coefficient was also calculated by comparing specimens with and without weld lines. The tensile and flexural properties of PA-CF composites significantly increased with the rise of fiber content for specimens without weld lines, while injection temperature and pressure demonstrated slight influences on mechanical properties. However, the existence of weld lines had negative influences on the mechanical properties of PA-CF composites due to poor fiber orientation in weld line regions. The weld line coefficient of PA-CF composites decreased as fiber content increased, indicating that the damage of weld lines to mechanical properties increased. The microstructure analysis showed that there were a large number of fibers distributed vertically to flow direction in weld lines regions, which could not play a reinforcing role. In addition, increasing injection temperature and pressure facilitated fiber orientation, which improved the mechanical properties of composites with low fiber content, while weakening composites with high fiber content instead. This article provides practical information for product design containing weld lines, which helps to optimize the forming process and formula design of PA-CF composites with weld lines. Full article
Show Figures

Figure 1

12 pages, 3482 KiB  
Article
Effect of pH Hydrolysis on the Recovery of Antimony from Spent Electrolytes from Copper Production
by Eduardo Díaz Gutiérrez, José Antonio Maldonado Calvo, José María Gallardo Fuentes and Antonio Paúl Escolano
Materials 2023, 16(11), 3918; https://doi.org/10.3390/ma16113918 - 23 May 2023
Cited by 3 | Viewed by 1084
Abstract
This study examined how pH hydrolysis affects the recovery process for antimony extracted from spent electrolytes. Various OH reagents were used to adjust the pH levels. The findings reveal that pH plays a crucial role in determining the optimal conditions for extracting [...] Read more.
This study examined how pH hydrolysis affects the recovery process for antimony extracted from spent electrolytes. Various OH reagents were used to adjust the pH levels. The findings reveal that pH plays a crucial role in determining the optimal conditions for extracting antimony. The results show that NH4OH and NaOH are more effective compared to water, with optimal conditions at pH 0.5 for water and pH 1 for NH4OH and NaOH, resulting in average antimony extraction yields of 90.4%, 96.1%, and 96.7%, respectively. Furthermore, this approach helps to improve both crystallography and purity related to recovered antimony samples obtained through recycling processes. The solid precipitates obtained lack a crystalline structure, making it difficult to identify the compounds formed, but element concentrations suggest the presence of oxychloride or oxide compounds. Arsenic is incorporated into all solids, affecting the purity of the product, and water showing higher antimony content (68.38%) and lower arsenic values (8%) compared to NaOH and NH4OH. Bismuth integration into solids is less than arsenic (less than 2%) and remains unaffected by pH levels except in tests with water, where a bismuth hydrolysis product is identified at pH 1, accounting for the observed reduction in antimony extraction yields. Full article
Show Figures

Figure 1

Back to TopTop