The 2023 MDPI Annual Report has
been released!
 
14 pages, 1122 KiB  
Article
Sustainable Hybrid Lightweight Aggregate Concrete Using Recycled Expanded Polystyrene
by D. González-Betancur, Ary A. Hoyos-Montilla and Jorge I. Tobón
Materials 2024, 17(10), 2368; https://doi.org/10.3390/ma17102368 (registering DOI) - 15 May 2024
Abstract
Global concrete production, reaching 14×1013m3/year, raises environmental concerns due to the resource-intensive nature of ordinary Portland cement (OPC) manufacturing. Simultaneously, 32.7×109 kg/year of expanded polystyrene (EPS) waste poses ecological threats. This research explores [...] Read more.
Global concrete production, reaching 14×1013m3/year, raises environmental concerns due to the resource-intensive nature of ordinary Portland cement (OPC) manufacturing. Simultaneously, 32.7×109 kg/year of expanded polystyrene (EPS) waste poses ecological threats. This research explores the mechanical behavior of lightweight concrete (LWAC) using recycled EPS manufactured with a hybrid cement mixture (OPC and alkali-activated cement). These types of cement have been shown to improve the compressive strength of concrete, while recycled EPS significantly decreases concrete density. However, the impact of these two materials on the LWAC mechanical behavior is unclear. LWAC comprises 35% lightweight aggregates (LWA)—a combination of EPS and expanded clays (EC) — and 65% normal-weight aggregates. As a cementitious matrix, this LWAC employs 30% OPC and 70% alkaline-activated cement (AAC) based on fly ash (FA) and lime. Compressive strength tests after 28 curing days show a remarkable 48.8% improvement, surpassing the ACI 213R-03 standard requirement, which would allow this sustainable hybrid lightweight aggregate concrete to be used as structural lightweight concrete. Also obtained was a 21.5% reduction in density; this implies potential cost savings through downsizing structural elements and enhancing thermal and acoustic insulation. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy reveal the presence of C-S-H, C-(A)-S-H, and N-A-S-H gels. However, anhydrous products in the hybrid LWAC suggest a slower reaction rate. Further investigation into activator solution dosage and curing temperature is recommended for improved mechanical performance on the 28th day of curing. This research highlights the potential for sustainable construction incorporating waste and underscores the importance of refining activation parameters for optimal performance. Full article
(This article belongs to the Special Issue Advances in the Design and Properties of New Ecoconcrete Formulations)
Show Figures

Figure 1

18 pages, 7501 KiB  
Article
Returning Cropland to Grassland as a Potential Method for Increasing Carbon Storage in Dry-Hot Valley Areas
by Yakai He, Weili Kou, Yue Chen, Hongyan Lai and Kaifu Zhao
Sustainability 2024, 16(10), 4150; https://doi.org/10.3390/su16104150 (registering DOI) - 15 May 2024
Abstract
A key aspect of mitigating global climate warming is enhancing the carbon storage capacity of terrestrial ecosystems. China’s Grain for Green Program (GFGP) is the largest ecological restoration project in the world, which is closely associated with land use change. A systematic assessment [...] Read more.
A key aspect of mitigating global climate warming is enhancing the carbon storage capacity of terrestrial ecosystems. China’s Grain for Green Program (GFGP) is the largest ecological restoration project in the world, which is closely associated with land use change. A systematic assessment of the GFGP’s impact on regional carbon storage is of great significance for promoting regional development and maintaining ecosystem stability. Therefore, this study selects a typical dry-hot valley area—Yanjin County—as the study area, which serves as an ecological protection barrier in Southwest China. We employed the InVEST model and Geo-detector model based on land use data from three periods (2000, 2014, and 2019), combined with static overlay analysis methods, in order to evaluate the impact of the implementation of GFGP on the spatial and temporal distribution of carbon storage. We also explored the driving factors of the spatial differentiation of carbon storage. The results indicate that, since the implementation of the GFGP, a total of 180.03 km2 of cropland has been converted to forestland, increasing the forest cover rate from 81.83% to 83.37%. The project has contributed 5.88 × 105 t to regional carbon storage, effectively offsetting carbon emissions caused by human activities such as urban expansion while also promoting the growth of regional carbon storage. The implementation of the GFGP has led to changes in three types of land use. Among them, converting cropland to forestland (3262 t/km2) is the most effective carbon sequestration method, and converting cropland to grassland (2530 t/km2) has shown great potential in carbon sequestration. Additionally, the study found that elevation (0.038–0.059) is the main factor affecting the spatial differentiation of carbon storage, and the interaction between elevation and other factors can effectively enhance the carbon sequestration capacity of regional ecosystems. Overall, the GFGP not only plays a significant role in combating climate warming but also makes an important contribution to improving the stability and sustainability of regional ecosystems. Full article
25 pages, 7725 KiB  
Article
Intelligent Vehicle Path Planning Based on Optimized A* Algorithm
by Liang Chu, Yilin Wang, Shibo Li, Zhiqi Guo, Weiming Du, Jinwei Li and Zewei Jiang
Sensors 2024, 24(10), 3149; https://doi.org/10.3390/s24103149 (registering DOI) - 15 May 2024
Abstract
With the rapid development of the intelligent driving technology, achieving accurate path planning for unmanned vehicles has become increasingly crucial. However, path planning algorithms face challenges when dealing with complex and ever-changing road conditions. In this paper, aiming at improving the accuracy and [...] Read more.
With the rapid development of the intelligent driving technology, achieving accurate path planning for unmanned vehicles has become increasingly crucial. However, path planning algorithms face challenges when dealing with complex and ever-changing road conditions. In this paper, aiming at improving the accuracy and robustness of the generated path, a global programming algorithm based on optimization is proposed, while maintaining the efficiency of the traditional A* algorithm. Firstly, turning penalty function and obstacle raster coefficient are integrated into the search cost function to increase the adaptability and directionality of the search path to the map. Secondly, an efficient search strategy is proposed to solve the problem that trajectories will pass through sparse obstacles while reducing spatial complexity. Thirdly, a redundant node elimination strategy based on discrete smoothing optimization effectively reduces the total length of control points and paths, and greatly reduces the difficulty of subsequent trajectory optimization. Finally, the simulation results, based on real map rasterization, highlight the advanced performance of the path planning and the comparison among the baselines and the proposed strategy showcases that the optimized A* algorithm significantly enhances the security and rationality of the planned path. Notably, it reduces the number of traversed nodes by 84%, the total turning angle by 39%, and shortens the overall path length to a certain extent. Full article
(This article belongs to the Special Issue Integrated Control and Sensing Technology for Electric Vehicles)
Show Figures

Figure 1

22 pages, 4309 KiB  
Article
Reliability and Residual Life of Cold Standby Systems
by Longlong Liu, Xiaochuan Ai and Jun Wu
Mathematics 2024, 12(10), 1540; https://doi.org/10.3390/math12101540 (registering DOI) - 15 May 2024
Abstract
In this study, we conduct a reliability characterisation study of cold standby systems. Utilising synthetic rectangular formulas and cold preparedness equivalent models for cold standby systems, we analyse the lifetimes of several typical configurations, including series, parallel, and k/n:m voting systems. This study [...] Read more.
In this study, we conduct a reliability characterisation study of cold standby systems. Utilising synthetic rectangular formulas and cold preparedness equivalent models for cold standby systems, we analyse the lifetimes of several typical configurations, including series, parallel, and k/n:m voting systems. This study proposes system equivalent models for various types of cold standby systems, all composed of components that follow the same exponential distribution. We use the equivalent model to determine the optimal timing for the use of cold spares and derive the reliability function and residual lifetime function for each type of system. To demonstrate the validity of our model, the Monte Carlo simulation is strategically designed based on the system failure rate function. The experimental results are then compared with those obtained from the numerical model, highlighting that the numerical method incurs a lower time cost. Full article
Show Figures

Figure 1

18 pages, 8308 KiB  
Article
Mechanisms for deNOx and deN2O Processes on FAU Zeolite with a Bimetallic Cu-Fe Dimer in the Presence of a Hydroxyl Group—DFT Theoretical Calculations
by Izabela Kurzydym and Izabela Czekaj
Molecules 2024, 29(10), 2329; https://doi.org/10.3390/molecules29102329 (registering DOI) - 15 May 2024
Abstract
In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the [...] Read more.
In this paper, a detailed mechanism is discussed for two processes: deNOx and deN2O. An FAU catalyst was used for the reaction with Cu-Fe bimetallic adsorbates represented by a dimer with bridged oxygen. Partial hydration of the metal centres in the dimer was considered. Ab initio calculations based on the density functional theory were used. The electron parameters of the structures obtained were also analysed. Visualisation of the orbitals of selected structures and their interpretations are presented. The presented research allowed a closer look at the mechanisms of processes that are very common in the automotive and chemical industries. Based on theoretical modelling, it was possible to propose the most efficient catalyst that could find potential application in industry–this is the FAU catalyst with a Cu-O-Fe bimetallic dimer with a hydrated copper centre. The essential result of our research is the improvement in the energetics of the reaction mechanism by the presence of an OH group, which will influence the way NO and NH3 molecules react with each other in the deNOx process depending on the industrial conditions of the process. Our theoretical results suggest also how to proceed with the dosage of NO and N2O during the industrial process to increase the desired reaction effect. Full article
(This article belongs to the Section Computational and Theoretical Chemistry)
Show Figures

Figure 1

15 pages, 296 KiB  
Article
On Some Multipliers Related to Discrete Fractional Integrals
by Jinhua Cheng
Mathematics 2024, 12(10), 1545; https://doi.org/10.3390/math12101545 (registering DOI) - 15 May 2024
Abstract
This paper explores the properties of multipliers associated with discrete analogues of fractional integrals, revealing intriguing connections with Dirichlet characters, Euler’s identity, and Dedekind zeta functions of quadratic imaginary fields. Employing Fourier transform techniques, the Hardy–Littlewood circle method, and a discrete analogue of [...] Read more.
This paper explores the properties of multipliers associated with discrete analogues of fractional integrals, revealing intriguing connections with Dirichlet characters, Euler’s identity, and Dedekind zeta functions of quadratic imaginary fields. Employing Fourier transform techniques, the Hardy–Littlewood circle method, and a discrete analogue of the Stein–Weiss inequality on product space through implication methods, we establish pq bounds for these operators. Our results contribute to a deeper understanding of the intricate relationship between number theory and harmonic analysis in discrete domains, offering insights into the convergence behavior of these operators. Full article
(This article belongs to the Special Issue Fractional Calculus and Mathematical Applications, 2nd Edition)
20 pages, 2076 KiB  
Article
Research on Multi-Mode Control of Electro-Hydraulic Variable Displacement Pump Driven by Servo Motor
by Zhiqiang Zhang, Yupeng Yan, Lin Li, Qun Chao, Kunshan Jin and Zhiqi Liu
Actuators 2024, 13(5), 190; https://doi.org/10.3390/act13050190 (registering DOI) - 15 May 2024
Abstract
The electro-hydraulic power source with an electro-hydraulic variable pump driven by a servo motor is suitable for electrified construction machinery. To achieve better energy efficiency in different working conditions, the multi-mode control scheme was proposed for the electro-hydraulic power source. The control scheme [...] Read more.
The electro-hydraulic power source with an electro-hydraulic variable pump driven by a servo motor is suitable for electrified construction machinery. To achieve better energy efficiency in different working conditions, the multi-mode control scheme was proposed for the electro-hydraulic power source. The control scheme includes pressure control, flow control, and torque control modes. The switching rule among the three control modes was formulated based on the minimum pump pressure. The fuzzy PID controller was designed, and a composite flow regulation strategy was formulated, including the load-sensitive adaptive displacement regulation and servo motor variable speed regulation. The AMESim-Simulink co-simulation model of multi-mode control was established. The test platform was built, and the experimental study was carried out. The results indicate that the fuzzy PID control has a shorter response time and a more stable control effect compared with PID control. Additionally, the composite flow regulation strategy improves the flow regulation range by 36% and reduces the flow overshoot by 20% compared with the load-sensitive adaptive displacement regulation. As the main control valve received an opening step signal, the full flow regulation (7~81 L/min) of the power source took approximately 0.5 s to rise and 0.2 s to fall. The relative error of pressure difference for the main control valve was 0.63%. When receiving the pressure and torque step signal, the pump pressure and pump input torque both took approximately 0.45 s to rise and 0.2 s to fall. The relative errors of pump pressure and torque control were 0.2% and 0.16%, respectively. In the multi-mode control, the electro-hydraulic power source could switch smoothly between flow control mode, pressure control mode, and torque control mode. These results provide a reference for the multi-mode control of an electro-hydraulic power source with an electro-hydraulic variable pump driven by a servo motor. Full article
14 pages, 6007 KiB  
Article
Evaluation of the Performance of Pervious Concrete Inspired by CO2-Curing Technology
by Murugan Muthu and Łukasz Sadowski
Appl. Sci. 2024, 14(10), 4202; https://doi.org/10.3390/app14104202 (registering DOI) - 15 May 2024
Abstract
Urban runoff is acidic in nature and mainly consists of heavy metals and sediments. In this study, the pervious concrete samples were cured in a CO2-rich environment and their performance under runoff conditions was evaluated by passing different solutions containing clay [...] Read more.
Urban runoff is acidic in nature and mainly consists of heavy metals and sediments. In this study, the pervious concrete samples were cured in a CO2-rich environment and their performance under runoff conditions was evaluated by passing different solutions containing clay particles, heavy metal ions, and acid species. The compressive strength of these samples was reduced by up to 14% when they were cured in water instead of a CO2 environment. Heavy metal ions, including lead and zinc, in the simulated runoff were adsorbed in these pervious concrete samples by up to 96% and 80% at the end of the experiment, but the acid species in this runoff could leach calcium ions from the cement components during passage. Clay particles in the runoff were trapped in the flow channels of samples, which marginally reduced the percolation rate by up to 14%. Concrete carbonation reduced the release of calcium ions under runoff conditions, and zinc removal was relatively lower because of the nonavailability of hydroxyl sites in the interconnected pore structure. The weight and strength losses in the carbonated concrete samples were relatively lower at the end of the acid storage experiment, suggesting that CO2 curing reduces cement degradation in aggressive chemicals. The SEM and tomography images revealed the degraded microstructure, while the XRD results provided data on the mineralogical changes. CO2 curing improves the strength gain and service life of pervious concrete in runoff environments. Full article
(This article belongs to the Special Issue Advances in Cement-Based Materials)
16 pages, 930 KiB  
Article
Multidrug-Resistant Bacteria in Surgical Intensive Care Units: Antibiotic Susceptibility and β-Lactamase Characterization
by Daniela Bandić Pavlović, Mladen Pospišil, Marina Nađ, Vilena Vrbanović Mijatović, Josefa Luxner, Gernot Zarfel, Andrea Grisold, Dinko Tonković, Mirela Dobrić and Branka Bedenić
Pathogens 2024, 13(5), 411; https://doi.org/10.3390/pathogens13050411 (registering DOI) - 15 May 2024
Abstract
Multidrug-resistant (MDR) bacteria of the utmost importance are extended-spectrum β-lactamase (ESBL) and carbapenemase-producing Enterobacterales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp. (VRE). In this study, an evaluation of MDR bacteria in surgical intensive [...] Read more.
Multidrug-resistant (MDR) bacteria of the utmost importance are extended-spectrum β-lactamase (ESBL) and carbapenemase-producing Enterobacterales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp. (VRE). In this study, an evaluation of MDR bacteria in surgical intensive care units in a tertiary referral hospital was conducted. The study aimed to characterize β-lactamases and other resistance traits of Gram-negative bacteria isolated in surgical intensive care units (ICUs). Disk diffusion and the broth dilution method were used for antibiotic susceptibility testing, whereas ESBL screening was performed through a double disk synergy test and an inhibitor-based test with clavulanic acid. A total of 119 MDR bacterial isolates were analysed. ESBL production was observed in half of the Proteus mirabilis, 90% of the Klebsiella pneumoniae and all of the Enterobacter cloacae, P. mirabilis and Escherichia coli isolates. OXA-48 carbapenemase, carried by the L plasmid, was detected in 34 K. pneumoniae and one E. coli and Enterobacter cloacae complex isolates, whereas NDM occurred sporadically and was identified in three K. pneumoniae isolates. OXA-48 positive isolates coharboured ESBLs belonging to the CTX-M family in all but one isolate. OXA-23 carbapenemase was confirmed in all A. baumannii isolates. The findings of this study provide valuable insight of resistance determinants of Enterobacterales and A. baumannii which will enhance surveillance and intervention strategies that are necessary to curb the ever-growing carbapenem resistance rates. Full article
Show Figures

Figure 1

27 pages, 1468 KiB  
Article
Policy Assessment for Energy Transition to Zero- and Low-Emission Technologies in Pickup Trucks: Evidence from Mexico
by Julieth Stefany Garcia, Laura Milena Cárdenas, Jose Daniel Morcillo and Carlos Jaime Franco
Energies 2024, 17(10), 2386; https://doi.org/10.3390/en17102386 (registering DOI) - 15 May 2024
Abstract
The transport sector is under scrutiny because of its significant greenhouse gas emissions. Essential strategies, particularly the adoption of zero- and low-emission vehicles powered by electricity, are crucial for mitigating emissions in road transport. Pickups, which are integral to Mexico’s fleet, contribute to [...] Read more.
The transport sector is under scrutiny because of its significant greenhouse gas emissions. Essential strategies, particularly the adoption of zero- and low-emission vehicles powered by electricity, are crucial for mitigating emissions in road transport. Pickups, which are integral to Mexico’s fleet, contribute to such emissions. Thus, implementing effective policies targeting pickups is vital for reducing air pollution and aligning with Mexico’s decarbonization objectives. This paper presents a simulation model based on system dynamics to represent the adoption process of zero- and low-emission vehicles, with a focus on pickups and utilizing data from the Mexican case. Three policy evaluation scenarios are proposed based on the simulation model: business as usual; disincentives for zero- and low-emission vehicles; and incentives for unconventional vehicles. One of the most significant findings from this study is that even in a scenario with a greater number of vehicles in circulation, if the technology is fully electric, the environmental impact in terms of emissions is lower. Additionally, a comprehensive sensitivity analysis spanning a wide spectrum is undertaken through an extensive computational process, yielding multiple policy scenarios. The analysis indicates that to achieve a maximal reduction in the country’s emissions, promoting solely hybrid electric vehicles and plug-in hybrid electric vehicles is advisable, whereas internal combustion engines, vehicular natural gas, and battery electric vehicles should be discouraged. Full article
11 pages, 1445 KiB  
Article
Experimental Study on Near-Wall Laser-Induced Cavitation Bubble Micro-Dimple Formation on 7050 Aluminum Alloy
by Yupeng Cao, Ranran Hu, Weidong Shi and Rui Zhou
Water 2024, 16(10), 1410; https://doi.org/10.3390/w16101410 (registering DOI) - 15 May 2024
Abstract
To investigate the feasibility and formation laws of fabricating micro-dimples induced by near-wall laser-induced cavitation bubble (LICB) on 7050 aluminum alloy. A high-speed camera and a fiber-optic hydrophone system were used to capture pulsation evolution images and acoustic signals of LICB. Meanwhile, a [...] Read more.
To investigate the feasibility and formation laws of fabricating micro-dimples induced by near-wall laser-induced cavitation bubble (LICB) on 7050 aluminum alloy. A high-speed camera and a fiber-optic hydrophone system were used to capture pulsation evolution images and acoustic signals of LICB. Meanwhile, a three-dimensional profilometer was employed to examine the contour morphology of the surface micro-dimple on the specimen. The results show that at an energy level of 500 mJ, the total pulsation period for the empty bubble is 795 μs, with individual pulsation periods of 412.5 μs, 217 μs, and 165 μs for the first, second, and third cycles, respectively, with most energy of the laser and bubble being consumed during the first evolution period. Under the synergy of the plasma shock wave and collapse shock wave, a spherical dimple with a diameter of 450 μm is formed on the sample surface with copper foil as the absorption layer. A model of micro-dimple formed by LICB impact is established. As the energy increases, the depth of the surface micro-dimple peaks at an energy of 400 mJ and then decreases. The depth of the surface micro-dimple increases with the increase in the number of impacts; the optimal technology parameters for the micro-dimple formation by LICB impact are as follows: the absorption layer is copper foil, the energy is 400 mJ, and the number of impacts is three. Full article
(This article belongs to the Special Issue Hydraulics and Hydrodynamics in Fluid Machinery)
Show Figures

Figure 1

15 pages, 1057 KiB  
Article
Research on Phenolic Content and Its Antioxidant Activities in Fermented Rosa rugosa ‘Dianhong’ Petals with Brown Sugar
by Yueyue Cai, Merhaba Abla, Lu Gao, Jinsong Wu and Lixin Yang
Antioxidants 2024, 13(5), 607; https://doi.org/10.3390/antiox13050607 (registering DOI) - 15 May 2024
Abstract
Fermented Rosa rugosa ‘Dianhong’ petals with brown sugar, a biologically active food popularized in Dali Prefecture, Northwest Yunnan, China, are rich in bioactive compounds, especially polyphenols, exhibiting strong antioxidant activity. This study evaluated their antioxidant activities, total phenolic contents, and concentrations of [...] Read more.
Fermented Rosa rugosa ‘Dianhong’ petals with brown sugar, a biologically active food popularized in Dali Prefecture, Northwest Yunnan, China, are rich in bioactive compounds, especially polyphenols, exhibiting strong antioxidant activity. This study evaluated their antioxidant activities, total phenolic contents, and concentrations of polyphenols at different fermentation conditions using different assays: DPPH free-radical scavenging activity, Trolox equivalent antioxidant capacity (TEAC), ferric reducing antioxidant power (FRAP), Folin–Ciocalteu assays, and HPLC–MS/MS and HPLC–DAD methods. The results indicated that fermentation significantly increased (p < 0.05) the antioxidant activity and polyphenol concentration of R. rugosa ’Dianhong.’ Furthermore, Saccharomyces rouxii TFR-1 fermentation achieved optimal bioactivity earlier than natural fermentation. Overall, we found that the use of Saccharomyces rouxii (TFR-1) is a more effective strategy for the production of polyphenol-rich fermented R. rugosa ‘Dianhong’ petals with brown sugar compared to natural fermentation. Full article
(This article belongs to the Special Issue Antioxidant Properties and Applications of Food By-Products)
Show Figures

Graphical abstract

26 pages, 1069 KiB  
Article
Study on the Efficiency, Evolutionary Trend, and Influencing Factors of Rural–Urban Integration Development in Sichuan and Chongqing Regions under the Background of Dual Carbon
by Pan Jiang, Yirui Yang, Wei Ye, Liang Liu, Xinchen Gu, Haipeng Chen and Yuhan Zhang
Land 2024, 13(5), 696; https://doi.org/10.3390/land13050696 (registering DOI) - 15 May 2024
Abstract
Re-evaluating how urban and rural development can be integrated is a necessary step towards achieving the “dual-carbon” objective and facilitating a thorough transition towards a green and low-carbon economy and society. This study empirically investigates the geographical disparities, evolving patterns, and determinants of [...] Read more.
Re-evaluating how urban and rural development can be integrated is a necessary step towards achieving the “dual-carbon” objective and facilitating a thorough transition towards a green and low-carbon economy and society. This study empirically investigates the geographical disparities, evolving patterns, and determinants of the effectiveness of urban–rural integration development in Sichuan and Chongqing. Results of the study indicate that (1) the effectiveness of urban–rural integration development in Sichuan and Chongqing is generally poor, and external environmental factors adversely affect the urban–rural integration of economically developed cities; (2) the urban–rural integration development efficiency in Sichuan and Chongqing does not show a more obvious polarization phenomenon, but the gap between the cities gradually widens; and (3) regarding influencing factors, market dynamics are favorable to overall urban–rural integration development in the Sichuan and Chongqing regions, while the development of the digital economy and the level of financial development can exacerbate the imbalance of regional urban–rural integration development. Based on this premise, pertinent policy suggestions are offered to facilitate the merger of urban and rural areas and foster efficient development in the regions of Sichuan and Chongqing. Full article
(This article belongs to the Topic Low Carbon Economy and Sustainable Development)
17 pages, 1504 KiB  
Article
The Development of a Fully Renewable Lubricant: The Effect of Ethyl Cellulose on the Properties of a Polyhydroxyalkanoate (P34HB)-Based Grease
by Shanshan Yang, Bingbing Lai, Zongzhu Liu and Wenjing Lou
Sustainability 2024, 16(10), 4149; https://doi.org/10.3390/su16104149 (registering DOI) - 15 May 2024
Abstract
In the context of the ongoing evolution of the global economy and increasing environmental awareness, green sustainable development has emerged as a crucial pathway for future advancements in the lubrication industry. In this study, we prepared bio-based greases by employing a thickener system [...] Read more.
In the context of the ongoing evolution of the global economy and increasing environmental awareness, green sustainable development has emerged as a crucial pathway for future advancements in the lubrication industry. In this study, we prepared bio-based greases by employing a thickener system consisting of polyhydroxyalkanoate (P34HB) and ethyl cellulose, with castor oil serving as a base oil. The results indicate that ethyl cellulose significantly and effectively enhances the grease system’s mechanical and colloidal stability. Notably, the addition of 5 wt% ethyl cellulose leads to superior mechanical and colloidal stability, while increasing concentrations gradually result in rheological properties similar to those of oleogels. Furthermore, the wear volume of grease containing 5 wt% ethyl cellulose was reduced by 39.20% compared to that of a reference P34HB grease, demonstrating its exceptional wear resistance. The present study provides a theoretical foundation and empirical evidence for the future development of biodegradable greases as substitutes for non-degradable materials, thereby expanding the range of environmentally friendly greases formulated with biomass-based thickeners. Full article
(This article belongs to the Section Sustainable Materials)
20 pages, 727 KiB  
Article
Semantic Augmentation in Chinese Adversarial Corpus for Discourse Relation Recognition Based on Internal Semantic Elements
by Zheng Hua, Ruixia Yang, Yanbin Feng and Xiaojun Yin
Electronics 2024, 13(10), 1944; https://doi.org/10.3390/electronics13101944 (registering DOI) - 15 May 2024
Abstract
This paper proposes incorporating linguistic semantic information into discourse relation recognition and constructing a Semantic Augmented Chinese Discourse Corpus (SACA) comprising 9546 adversative complex sentences. In adversative complex sentences, we suggest a quadruple (P, Q, R, Qβ) [...] Read more.
This paper proposes incorporating linguistic semantic information into discourse relation recognition and constructing a Semantic Augmented Chinese Discourse Corpus (SACA) comprising 9546 adversative complex sentences. In adversative complex sentences, we suggest a quadruple (P, Q, R, Qβ) representing internal semantic elements, where the semantic opposition between Q and Qβ forms the basis of the adversative relationship. P denotes the premise, and R represents the adversative reason. The overall annotation approach of this corpus follows the Penn Discourse Treebank (PDTB), except for the classification of senses. We combined insights from the Chinese Discourse Treebank (CDTB) and obtained eight sense categories for Chinese adversative complex sentences. Based on this corpus, we explore the relationship between sense classification and internal semantic elements within our newly proposed Chinese Adversative Discourse Relation Recognition (CADRR) task. Leveraging deep learning techniques, we constructed various classification models and the model that utilizes internal semantic element features, demonstrating their effectiveness and the applicability of our SACA corpus. Compared with pre-trained models, our model incorporates internal semantic element information to achieve state-of-the-art performance. Full article
(This article belongs to the Special Issue Data Mining Applied in Natural Language Processing)
16 pages, 299 KiB  
Article
Model Selection for Exponential Power Mixture Regression Models
by Yunlu Jiang, Jiangchuan Liu, Hang Zou and Xiaowen Huang
Entropy 2024, 26(5), 422; https://doi.org/10.3390/e26050422 (registering DOI) - 15 May 2024
Abstract
Finite mixture of linear regression (FMLR) models are among the most exemplary statistical tools to deal with various heterogeneous data. In this paper, we introduce a new procedure to simultaneously determine the number of components and perform variable selection for the different regressions [...] Read more.
Finite mixture of linear regression (FMLR) models are among the most exemplary statistical tools to deal with various heterogeneous data. In this paper, we introduce a new procedure to simultaneously determine the number of components and perform variable selection for the different regressions for FMLR models via an exponential power error distribution, which includes normal distributions and Laplace distributions as special cases. Under some regularity conditions, the consistency of order selection and the consistency of variable selection are established, and the asymptotic normality for the estimators of non-zero parameters is investigated. In addition, an efficient modified expectation-maximization (EM) algorithm and a majorization-maximization (MM) algorithm are proposed to implement the proposed optimization problem. Furthermore, we use the numerical simulations to demonstrate the finite sample performance of the proposed methodology. Finally, we apply the proposed approach to analyze a baseball salary data set. Results indicate that our proposed method obtains a smaller BIC value than the existing method. Full article
(This article belongs to the Section Information Theory, Probability and Statistics)
19 pages, 7870 KiB  
Article
Discovery and Synthesis of Hydroxy-l-Proline Blockers of the Neutral Amino Acid Transporters SLC1A4 (ASCT1) and SLC1A5 (ASCT2)
by Brent R. Lyda, Gregory P. Leary, Jill Farnsworth, Benjamin Seaver, Derek Silvius, Michael P. Kavanaugh, C. Sean Esslinger and Nicholas R. Natale
Molecules 2024, 29(10), 2330; https://doi.org/10.3390/molecules29102330 (registering DOI) - 15 May 2024
Abstract
As a conformationally restricted amino acid, hydroxy-l-proline is a versatile scaffold for the synthesis of diverse multi-functionalized pyrrolidines for probing the ligand binding sites of biological targets. With the goal to develop new inhibitors of the widely expressed amino acid transporters [...] Read more.
As a conformationally restricted amino acid, hydroxy-l-proline is a versatile scaffold for the synthesis of diverse multi-functionalized pyrrolidines for probing the ligand binding sites of biological targets. With the goal to develop new inhibitors of the widely expressed amino acid transporters SLC1A4 and SLC1A5 (also known as ASCT1 and ASCT2), we synthesized and functionally screened synthetic hydroxy-l-proline derivatives using electrophysiological and radiolabeled uptake methods against amino acid transporters from the SLC1, SLC7, and SLC38 solute carrier families. We have discovered a novel class of alkoxy hydroxy-pyrrolidine carboxylic acids (AHPCs) that act as selective high-affinity inhibitors of the SLC1 family neutral amino acid transporters SLC1A4 and SLC1A5. AHPCs were computationally docked into a homology model and assessed with respect to predicted molecular orientation and functional activity. The series of hydroxyproline analogs identified here represent promising new agents to pharmacologically modulate SLC1A4 and SLC1A5 amino acid exchangers which are implicated in numerous pathophysiological processes such as cancer and neurological diseases. Full article
(This article belongs to the Section Medicinal Chemistry)
Show Figures

Figure 1

12 pages, 2842 KiB  
Article
Development of MetaXplore: An Interactive Tool for Targeted Metagenomic Analysis
by Naima Bel Mokhtar, Elias Asimakis, Ioannis Galiatsatos, Amal Maurady, Panagiota Stathopoulou and George Tsiamis
Curr. Issues Mol. Biol. 2024, 46(5), 4803-4814; https://doi.org/10.3390/cimb46050289 (registering DOI) - 15 May 2024
Abstract
Over the last decades, the analysis of complex microbial communities by high-throughput sequencing of marker gene amplicons has become routine work for many research groups. However, the main challenges faced by scientists who want to make use of the generated sequencing datasets are [...] Read more.
Over the last decades, the analysis of complex microbial communities by high-throughput sequencing of marker gene amplicons has become routine work for many research groups. However, the main challenges faced by scientists who want to make use of the generated sequencing datasets are the lack of expertise to select a suitable pipeline and the need for bioinformatics or programming skills to apply it. Here, we present MetaXplore, an interactive, user-friendly platform that enables the discovery and visualization of amplicon sequencing data. Currently, it provides a set of well-documented choices for downstream analysis, including alpha and beta diversity analysis, taxonomic composition, differential abundance analysis, identification of the core microbiome within a population, and biomarker analysis. These features are presented in a user-friendly format that facilitates easy customization and the generation of publication-quality graphics. MetaXplore is implemented entirely in the R language using the Shiny framework. It can be easily used locally on any system with R installed, including Windows, Mac OS, and most Linux distributions, or remotely via a web server without bioinformatic expertise. It can also be used as a framework for advanced users who can modify and expand the tool. Full article
Show Figures

Figure 1

12 pages, 35525 KiB  
Article
AZ91 Magnesium Alloy CMT Cladding Layer Processed Using Friction Stir Processing: Effect of Traverse Speed on Microstructure and Mechanical Properties
by Huichao Zhao, Junqi Shen, Shengsun Hu, Yahui Zhen and Yang Chen
Materials 2024, 17(10), 2348; https://doi.org/10.3390/ma17102348 (registering DOI) - 15 May 2024
Abstract
Friction stir processing (FSP) is a solid-state treating method to enhance the mechanical properties of materials by altering their microstructure. In this study, FSP was applied to the AZ91 magnesium alloy cladding layer prepared using cold metal transition (CMT) technology, and the purpose [...] Read more.
Friction stir processing (FSP) is a solid-state treating method to enhance the mechanical properties of materials by altering their microstructure. In this study, FSP was applied to the AZ91 magnesium alloy cladding layer prepared using cold metal transition (CMT) technology, and the purpose was to investigate the effect of the traverse speed of the H13 steel stirring head under a constant rotation speed on the microstructure and mechanical properties of the cladding layer. The results demonstrated that FSP could effectively decrease the grain size of the cladding layer and lead to the dispersion and dissolution of the coarse β-Mg17Al12 second phase into the α-Mg matrix. The mechanical characteristics of the processed cladding layer were significantly enhanced compared to the unprocessed cladding layer due to the grain refinement and second-phase strengthening induced by FSP. When the stirring head rotation speed was set at 300 r/min, the average microhardness and tensile properties of the specimens showed a tendency of initially increasing and then dropping as the traverse speed increased. The cladding layer, obtained at a traverse speed of 60 mm/min, displayed optimal mechanical properties with an average microhardness, tensile strength, and elongation of 85.6 HV0.1, 278.5 MPa, and 13.4%, respectively. Full article
Show Figures

Figure 1

16 pages, 8394 KiB  
Article
Design of a Low-Cost Open-Top Chamber Facility for the Investigation of the Effects of Elevated Carbon Dioxide Levels on Plant Growth
by Nicola Novello, Mani Naiker, Haydee Laza, Kerry B. Walsh and Sabine Tausz-Posch
Hardware 2024, 2(2), 138-153; https://doi.org/10.3390/hardware2020007 - 15 May 2024
Abstract
Open-top chambers (OTCs) consist of semi-open enclosures used to investigate the impact of elevated carbon dioxide [CO2] on crops and larger plant communities. OTCs have lower operational costs than alternatives such as controlled environment cabinets and Free Air Carbon Dioxide Enrichment [...] Read more.
Open-top chambers (OTCs) consist of semi-open enclosures used to investigate the impact of elevated carbon dioxide [CO2] on crops and larger plant communities. OTCs have lower operational costs than alternatives such as controlled environment cabinets and Free Air Carbon Dioxide Enrichment (FACE). A low-cost design is presented for an OTC with a surface area of 1.2 m2 and a target elevated CO2 concentration [CO2] of 650 µmol mol−1 adequate for trials involving cereals or grain legumes. The elevated CO2 chambers maintained an average concentration ± standard deviation of 652 ± 37 µmol mol−1 despite wind and air turbulences, in comparison to 407 ± 10 µmol mol−1 for non-enriched chambers. Relative to ambient (non-chamber) conditions, plants in the chambers were exposed to slightly warmer conditions (2.3 °C in daylight hours; 0.6 °C during night environment). The materials’ cost for constructing the chambers was USD 560 per chamber, while the CO2 control system for four chambers dedicated to CO2-enriched conditions cost USD 5388. To maintain the concentration of 650 µmol mol−1 during daylight hours, each chamber consumed 1.38 L min−1 of CO2. This means that a size G CO2 cylinder was consumed in 8–9 days in the operation of two chambers (at USD 40). Full article
Show Figures

Figure 1

15 pages, 1265 KiB  
Review
Thermal Fatigue Failure of Micro-Solder Joints in Electronic Packaging Devices: A Review
by Lei Li, Xinyu Du, Jibing Chen and Yiping Wu
Materials 2024, 17(10), 2365; https://doi.org/10.3390/ma17102365 (registering DOI) - 15 May 2024
Abstract
In electronic packaging products in the service process, the solder joints experience thermal fatigue due to temperature cycles, which have a significant influence on the performance of electronic products and the reliability of solder joints. In this paper, the thermal fatigue failure mechanism [...] Read more.
In electronic packaging products in the service process, the solder joints experience thermal fatigue due to temperature cycles, which have a significant influence on the performance of electronic products and the reliability of solder joints. In this paper, the thermal fatigue failure mechanism of solder joints in microelectronic packages, the microstructure changes of the thermal fatigue process, the influence factors on the joint fatigue life, and the simulation analysis and forecasting of thermal fatigue life are reviewed. The results show that the solder joints are heterogeneously coarsened, and this leads to fatigue cracks occurring under the elevated high-temperature phase of alternating temperature cycles. However, the thickness of the solder and the hold time in the high-temperature phase do not significantly influence the thermal fatigue. The coarsened region and the IMC layer thicken with the number of cycles, and the cracks initiate and propagate along the interface between the intermetallic compound (IMC) layer and coarsened region, eventually leading to solder joint failure. For lead-containing and lead-free solders, the lead-containing solder shows a faster fatigue crack growth rate and propagates by transgranular mode. Temperature and frequency affect the thermal fatigue life of solder joints to different degrees, and the fatigue lifetime of solder joints can be predicted through a variety of methods and simulated crack trajectories, but also through the use of a unified constitutive model and finite element analysis for prediction. Full article
(This article belongs to the Special Issue Advances in Electronics Packaging Materials and Technology)
17 pages, 5931 KiB  
Article
Experimental Study on Enhancing the Mechanical Properties of Sandy Soil by Combining Microbial Mineralization Technology with Silty Soil
by Jun Hu, Fei Fan, Luyan Huang and Junchao Yu
Materials 2024, 17(10), 2362; https://doi.org/10.3390/ma17102362 (registering DOI) - 15 May 2024
Abstract
Currently, coastal sandy soils face issues such as insufficient foundation strength, which has become one of the crucial factors constraining urban development. Geotechnical engineering, as a traditional discipline, breaks down disciplinary barriers, promotes interdisciplinary integration, and realizes the green ecological and low-carbon development [...] Read more.
Currently, coastal sandy soils face issues such as insufficient foundation strength, which has become one of the crucial factors constraining urban development. Geotechnical engineering, as a traditional discipline, breaks down disciplinary barriers, promotes interdisciplinary integration, and realizes the green ecological and low-carbon development of geotechnical engineering, which is highly important. Based on the “dual carbon” concept advocating a green and environmentally friendly lifestyle, Bacillus spores were utilized to induce calcium carbonate precipitation technology (MICP) to solidify coastal sandy soils, leveraging the rough-surface and low-permeability characteristics of silty soil. The mechanical-strength variations in the samples were explored through experiments, such as calcium carbonate generation rate tests, non-consolidated undrained triaxial shear tests, and scanning electron microscopy (SEM) experiments, to investigate the MICP solidification mechanism. The results indicate that by incorporating silty soil into sandy soil for MICP solidification, the calcium carbonate generation rates of the samples were significantly increased. With the increase in the silty-soil content, the enhancement range was 0.58–3.62%, with the maximum calcium carbonate generation rate occurring at a 5% content level. As the silty-soil content gradually increased from 1% to 5%, the peak deviator stress increased by 4.2–43.2%, enhancing the sample shear strength. Furthermore, the relationship between the internal-friction angle, cohesion, and shear strength further validates the enhancement of the shear strength. Silty soil plays roles in adsorption and physical filling during the MICP solidification process, reducing the inter-particle pores in sandy soil, increasing the compactness, providing adsorption sites, and enhancing the calcium carbonate generation rate, thereby improving the shear strength. The research findings can provide guidance for reinforcing poor coastal sandy-soil foundations in various regions. Full article
(This article belongs to the Section Mechanics of Materials)
9 pages, 769 KiB  
Communication
Survey of Nutrition Knowledge, Attitudes, and Preferred Informational Sources among Students at a Southwestern University in the United States: A Brief Report
by Caroline H. Geist, Deana Hildebrand, Bryant H. Keirns and Sam R. Emerson
Dietetics 2024, 3(2), 170-178; https://doi.org/10.3390/dietetics3020014 - 15 May 2024
Abstract
The purpose of this study was to investigate nutrition perspectives, basic nutrition knowledge, and preferred sources of nutrition information among students at a southwestern university in the US. An original online survey was used to evaluate common sources of nutrition information, factors viewed [...] Read more.
The purpose of this study was to investigate nutrition perspectives, basic nutrition knowledge, and preferred sources of nutrition information among students at a southwestern university in the US. An original online survey was used to evaluate common sources of nutrition information, factors viewed as comprising a healthy dietary pattern, and attitudes toward nutrition information and recommendations. A total of 316 participants completed the survey. Prioritizing fruits and vegetables was the most common response (97%) for characterizing healthy eating. When asked which factors characterize a non-healthy pattern of eating, eating sweets was the top response (83%). The most common sources of nutrition information reported were word of mouth/friends and family (56%), followed by social media (45%). The majority felt that nutrition recommendations are constantly changing (78%) and that nutrition information is confusing (55%). Our data indicate that most students rely primarily on informal sources of nutrition information. However, our preliminary data also suggest that many students have a fair understanding of basic principles of healthy eating. More research in a broader and more diverse sample is needed to validate these findings. Full article
Show Figures

Figure 1

Open Access Journals

Browse by Indexing Browse by Subject Selected Journals
Back to TopTop