The 2023 MDPI Annual Report has
been released!
 
19 pages, 1628 KiB  
Article
A Multiscale Statistical Analysis of Rough Surfaces and Applications to Tribology
by Feodor M. Borodich, Andrey Pepelyshev and Xiaoqing Jin
Mathematics 2024, 12(12), 1804; https://doi.org/10.3390/math12121804 (registering DOI) - 10 Jun 2024
Abstract
Mathematical modelling of surface roughness is of significant interest for a variety of modern applications, including, but not limited to, tribology and optics. The most popular approaches to modelling rough surfaces are reviewed and critically examined. By providing counterexamples, it is shown that [...] Read more.
Mathematical modelling of surface roughness is of significant interest for a variety of modern applications, including, but not limited to, tribology and optics. The most popular approaches to modelling rough surfaces are reviewed and critically examined. By providing counterexamples, it is shown that approaches based solely on the use of the fractal geometry or power spectral density have many drawbacks. It is recommended to avoid these approaches. It is argued that the surfaces that cannot be distinguished from the original rough surfaces can be synthesised by employing the concept of the representative elementary pattern of roughness (REPR), i.e., the smallest interval (or area) of a rough surface that statistically represents the whole surface. The REPR may be extracted from surface measurement data by the use of the “moving window” technique in combination with the Kolmogorov–Smirnov statistic. Full article
(This article belongs to the Special Issue Multiscale Mathematical Modeling)
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Article
Common Attractors for Generalized F-Iterated Function Systems in G-Metric Spaces
by Talat Nazir and Sergei Silvestrov
Fractal Fract. 2024, 8(6), 346; https://doi.org/10.3390/fractalfract8060346 (registering DOI) - 10 Jun 2024
Abstract
In this paper, we study the generalized F-iterated function system in G-metric space. Several results of common attractors of generalized iterated function systems obtained by using generalized F-Hutchinson operators are also established. We prove that the triplet of F-Hutchinson [...] Read more.
In this paper, we study the generalized F-iterated function system in G-metric space. Several results of common attractors of generalized iterated function systems obtained by using generalized F-Hutchinson operators are also established. We prove that the triplet of F-Hutchinson operators defined for a finite number of general contractive mappings on a complete G-metric space is itself a generalized F-contraction mapping on a space of compact sets. We also present several examples in 2-D and 3-D for our results. Full article
(This article belongs to the Section General Mathematics, Analysis)
23 pages, 5245 KiB  
Article
Study of the Myosin Relay Helix Peptide by Molecular Dynamics Simulations, Pump-Probe and 2D Infrared Spectroscopy
by Holly Freedman and Jack A. Tuszynski
Int. J. Mol. Sci. 2024, 25(12), 6406; https://doi.org/10.3390/ijms25126406 (registering DOI) - 10 Jun 2024
Abstract
The Davydov model was conjectured to describe how an amide I excitation created during ATP hydrolysis in myosin might be significant in providing energy to drive myosin’s chemomechanical cycle. The free energy surfaces of the myosin relay helix peptide dissolved in 2,2,2-trifluoroethanol (TFE), [...] Read more.
The Davydov model was conjectured to describe how an amide I excitation created during ATP hydrolysis in myosin might be significant in providing energy to drive myosin’s chemomechanical cycle. The free energy surfaces of the myosin relay helix peptide dissolved in 2,2,2-trifluoroethanol (TFE), determined by metadynamics simulations, demonstrate local minima differing in free energy by only ~2 kT, corresponding to broken and stabilized hydrogen bonds, respectively. Experimental pump-probe and 2D infrared spectroscopy were performed on the peptide dissolved in TFE. The relative heights of two peaks seen in the pump-probe data and the corresponding relative volumes of diagonal peaks seen in the 2D-IR spectra at time delays between 0.5 ps and 1 ps differ noticeably from what is seen at earlier or later time delays or in the linear spectrum, indicating that a vibrational excitation may influence the conformational state of this helix. Thus, it is possible that the presence of an amide I excitation may be a direct factor in the conformational state taken on by the myosin relay helix following ATP hydrolysis in myosin. Full article
(This article belongs to the Special Issue Conformational Studies of Proteins and Peptides)
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15 pages, 947 KiB  
Article
Theoretical Insight into Psittacofulvins and Their Derivatives
by Marcin Molski
Molecules 2024, 29(12), 2760; https://doi.org/10.3390/molecules29122760 (registering DOI) - 10 Jun 2024
Abstract
Psittacofulvins are polyenal dyes responsible for coloring parrot feathers and protecting them against photo-oxidation, harmful radicals, and bacterial degradation. To explain the unusual properties of these compounds, the thermodynamic and global chemical activity descriptors characterizing four natural and three synthetic psittacofulvins, as well [...] Read more.
Psittacofulvins are polyenal dyes responsible for coloring parrot feathers and protecting them against photo-oxidation, harmful radicals, and bacterial degradation. To explain the unusual properties of these compounds, the thermodynamic and global chemical activity descriptors characterizing four natural and three synthetic psittacofulvins, as well as their hydroxyl, carboxyl and dialdehyde derivatives, were determined. To this aim, the DFT method at the B3LYP/QZVP theory level and the C-PCM solvation model were used. The calculations enabled the selection of the projected compounds for the greatest bioactivity and potential applicability as multifunctional ingredients in medicines, cosmetics, supplements, and food, in which they may play a triple role as preservative, radical scavenger, and coloring agent. The results obtained provide arguments for the identification of a fifth psittacofulvin within the parrot feather pigment, characterized by ten conjugated double bonds (docosadecaenal). Full article
(This article belongs to the Special Issue Natural Antioxidants, Dyes and Their Synthetic Analogs)
Article
Metagenomics Analysis Reveals the Composition and Functional Differences of Fecal Microbiota in Wild, Farm, and Released Chinese Three-Keeled Pond Turtles (Mauremys reevesii)
by Ijaz Khan, Rongping Bu, Zeeshan Ali, Muhammad Shahid Iqbal, Haitao Shi, Li Ding and Meiling Hong
Animals 2024, 14(12), 1750; https://doi.org/10.3390/ani14121750 (registering DOI) - 10 Jun 2024
Abstract
The intestine of living organisms harbors different microbiota associated with the biological functioning and health of the host and influences the process of ecological adaptation. Here, we studied the intestinal microbiota’s composition and functional differences using 16S rRNA and metagenomic analysis in the [...] Read more.
The intestine of living organisms harbors different microbiota associated with the biological functioning and health of the host and influences the process of ecological adaptation. Here, we studied the intestinal microbiota’s composition and functional differences using 16S rRNA and metagenomic analysis in the wild, farm, and released Chinese three-keeled pond turtle (Mauremys reevesii). At the phylum level, Bacteroidota dominated, followed by Firmicutes, Fusobacteriota, and Actinobacteriota in the wild group, but Chloroflexi was more abundant in the farm and released groups. Moreover, Chryseobacterium, Acinetobacter, Comamonas, Sphingobacterium, and Rhodobacter were abundant in the released and farm cohorts, respectively. Cetobacterium, Paraclostridium, Lysobacter, and Leucobacter showed an abundance in the wild group. The Kyoto Encyclopedia of Genes and Genomes (KEGG) database revealed that the relative abundance of most pathways was significantly higher in the wild turtles (carbohydrate metabolism, lipid metabolism, metabolism of cofactors, and vitamins). The comprehensive antibiotic resistance database (CARD) showed that the antibiotic resistance gene (ARG) subtype macB was the most abundant in the farm turtle group, while tetA was higher in the wild turtles, and srpYmcr was higher in the released group. Our findings shed light on the association between the intestinal microbiota of M. reevesii and its habitats and could be useful for tracking habitats to protect and conserve this endangered species. Full article
(This article belongs to the Section Animal Genetics and Genomics)
12 pages, 234 KiB  
Article
Effects of Dietary Protein Level and Rumen-Protected Methionine and Lysine on Growth Performance, Rumen Fermentation and Serum Indexes for Yaks
by Haibo Wang, Jianhui Fu, Xia Wu, Yadong Wang, Wenjie Li, Yanling Huang, Jincheng Zhong and Zhongli Peng
Animals 2024, 14(12), 1751; https://doi.org/10.3390/ani14121751 (registering DOI) - 10 Jun 2024
Abstract
This study investigated the effects of the dietary protein level and rumen-protected methionine and lysine (RPML) on the growth performance, rumen fermentation, and serum indexes of yaks. Thirty-six male yaks were randomly assigned to a two by three factorial experiment with two protein [...] Read more.
This study investigated the effects of the dietary protein level and rumen-protected methionine and lysine (RPML) on the growth performance, rumen fermentation, and serum indexes of yaks. Thirty-six male yaks were randomly assigned to a two by three factorial experiment with two protein levels, 15.05% and 16.51%, and three RPML levels: 0% RPML; 0.05% RPMet and 0.15% RPLys; and 0.1% RPMet and 0.3% RPLys. The trial lasted for sixty days. The results showed that the low-protein diet increased the DMI and feed conversion ratio of yaks. The diet supplemented with RPML increased the activities of IGF1 and INS and nutrient digestibility. The high-protein diet decreased the rumen butyrate concentration and increased the rumen isovalerate concentration. The low-protein diet supplemented with RPML increased the rumen pH and the concentrations of total volatile fatty acids, butyrate and NH3-N; the high-protein diet supplemented with a high level of RPML decreased the rumen pH and the concentrations of isobutyrate, isovalerate, propionate and NH3-N. The low-protein diet supplemented with RPML increased the total antioxidant capacity and glutathione peroxidase activity, along with the concentrations of malondialdehyde and amino acids such as aspartic acid, lysine, cysteine, etc. In conclusion, a low-protein diet supplemented with RPML is beneficial for rumen and body health, physiological response, and metabolic status in yaks. Full article
(This article belongs to the Special Issue Nutrients and Feed Additives in Ruminants)
Article
Dexamethasone-Induced Insulin Resistance Attenuation by Oral Sulfur–Oxidovanadium(IV) Complex Treatment in Mice
by Eucilene K. Batista, Lidiane M. A. de Lima, Dayane A. Gomes, Debbie C. Crans, Wagner E. Silva, Mônica F. Belian and Eduardo C. Lira
Pharmaceuticals 2024, 17(6), 760; https://doi.org/10.3390/ph17060760 (registering DOI) - 10 Jun 2024
Abstract
Vanadium compounds are known to exert insulin-enhancing activity, normalize elevated blood glucose levels in diabetic subjects, and show significant activity in models of insulin resistance (IR). Faced with insulin resistance, the present work investigates the antidiabetic performance of a known oxidovanadium(IV)-based coordination compound—[V [...] Read more.
Vanadium compounds are known to exert insulin-enhancing activity, normalize elevated blood glucose levels in diabetic subjects, and show significant activity in models of insulin resistance (IR). Faced with insulin resistance, the present work investigates the antidiabetic performance of a known oxidovanadium(IV)-based coordination compound—[VIVO(octd)]—and effects associated with glucocorticoid-induced insulin resistance in mice. The effects of [VIVO(octd)] were evaluated in a female Swiss mice model of insulin resistance induced by seven days of dexamethasone treatment in comparison with groups receiving metformin treatment. Biological assays such as hematological, TyG index, hepatic lipids, glycogen, oxidative stress in the liver, and oral glucose tolerance tests were evaluated. [VIVO(octd)] was characterized with 51V NMR, infrared spectroscopy (FTIR), electron paramagnetic resonance (EPR), electronic absorption spectroscopy, and mass spectrometry (ESI–FT–MS). The [VIVO(octd)] oral treatment (50 mg/kg) had an antioxidant effect, reducing 50% of fast blood glucose (p < 0.05) and 25% of the TyG index, which is used to estimate insulin resistance (p < 0.05), compared with the non-treated group. The oxidovanadium–sulfur compound is a promising antihyperglycemic therapeutic, including in cases aggravated by insulin resistance induced by glucocorticoid treatment. Full article
31 pages, 34074 KiB  
Article
The Generation of High-Resolution Mapping Products for the Lunar South Pole Using Photogrammetry and Photoclinometry
by Pengying Liu, Xun Geng, Tao Li, Jiujiang Zhang, Yuying Wang, Zhen Peng, Yinhui Wang, Xin Ma and Qiudong Wang
Remote Sens. 2024, 16(12), 2097; https://doi.org/10.3390/rs16122097 (registering DOI) - 10 Jun 2024
Abstract
High-resolution and high-accuracy mapping products of the Lunar South Pole (LSP) will play a vital role in future lunar exploration missions. Existing lunar global mapping products cannot meet the needs of engineering tasks, such as landing site selection and rover trajectory planning, at [...] Read more.
High-resolution and high-accuracy mapping products of the Lunar South Pole (LSP) will play a vital role in future lunar exploration missions. Existing lunar global mapping products cannot meet the needs of engineering tasks, such as landing site selection and rover trajectory planning, at the LSP. The Lunar Reconnaissance Orbiter (LRO)’s narrow-angle camera (NAC) can acquire submeter images and has returned a large amount of data covering the LSP. In this study, we combine stereo-photogrammetry and photoclinometry to generate high-resolution digital orthophoto maps (DOMs) and digital elevation models (DEMs) using LRO NAC images for a candidate landing site at the LSP. The special illumination and landscape characteristics of the LSP make the derivation of high-accuracy mapping products from orbiter images extremely difficult. We proposed an easy-to-implement shadow recognition and contrast stretching method based on the histograms of the LRO NAC images, which is beneficial for photogrammetric and photoclinometry processing. In order to automatically generate tie points, we designed an image matching method considering LRO NAC images’ features of long strips and large data volumes. The terrain and smoothness constraints were introduced into the cost function of photoclinometry adjustment, excluding pixels in shadow areas. We used 61 LRO NAC images to generate mapping products covering an area of 400 km2. The spatial resolution of the generated DOMs was 1 m/pixel, and the grid spacing of the derived DEMs was 1 m (close to the spatial resolution of the original images). The generated DOMs achieved a relative accuracy of better than 1 pixel. The geometric accuracy of the DEM derived from photoclinometry was consistent with the lunar orbiter laser altimeter (LOLA) DEM with a root mean square error of 0.97 m and an average error of 0.17 m. Full article
(This article belongs to the Special Issue Remote Sensing and Photogrammetry Applied to Deep Space Exploration)
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14 pages, 3870 KiB  
Article
Assessment of Thermal Osteonecrosis during Bone Drilling Using a Three-Dimensional Finite Element Model
by Yung-Chuan Chen, Yi-Jung Tsai, Hao-Yuan Hsiao, Yen-Wei Chiu, You-Yao Hong, Yuan-Kun Tu and Chih-Kun Hsiao
Bioengineering 2024, 11(6), 592; https://doi.org/10.3390/bioengineering11060592 (registering DOI) - 10 Jun 2024
Abstract
Bone drilling is a common procedure used to create pilot holes for inserting screws to secure implants for fracture fixation. However, this process can increase bone temperature and the excessive heat can lead to cell death and thermal osteonecrosis, potentially causing early fixation [...] Read more.
Bone drilling is a common procedure used to create pilot holes for inserting screws to secure implants for fracture fixation. However, this process can increase bone temperature and the excessive heat can lead to cell death and thermal osteonecrosis, potentially causing early fixation failure or complications. We applied a three-dimensional dynamic elastoplastic finite element model to evaluate the propagation and distribution of heat during bone drilling and assess the thermally affected zone (TAZ) that may lead to thermal necrosis. This model investigates the parameters influencing bone temperature during bone drilling, including drill diameter, rotational speed, feed force, and predrilled hole. The results indicate that our FE model is sufficiently accurate in predicting the temperature rise effect during bone drilling. The maximum temperature decreases exponentially with radial distance. When the feed forces are 40 and 60 N, the maximum temperature does not exceed 45 °C. However, with feed forces of 10 and 20 N, both the maximum temperatures exceed 45 °C within a radial distance of 0.2 mm, indicating a high-risk zone for potential thermal osteonecrosis. With the two-stage drilling procedure, where a 2.5 mm pilot hole is predrilled, the maximum temperature can be reduced by 14 °C. This suggests that higher feed force and rotational speed and/or using a two-stage drilling process could mitigate bone temperature elevation and reduce the risk of thermal osteonecrosis during bone drilling. Full article
(This article belongs to the Section Biomedical Engineering and Biomaterials)
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Review
A Review of Non-Isolated High-Gain Y-Source Converters Topologies
by Hao Wang, Panbao Wang, Enpeng Yan, Wei Wang and Dianguo Xu
Energies 2024, 17(12), 2850; https://doi.org/10.3390/en17122850 (registering DOI) - 10 Jun 2024
Abstract
Due to the low voltage and high randomness of renewable energy, high-performance grid-connected converters are needed. With the advantages of a high boost ratio, flexible design, and simple control, the Y-Source Converter (YSC) is widely concerned. However, there are a few drawbacks to [...] Read more.
Due to the low voltage and high randomness of renewable energy, high-performance grid-connected converters are needed. With the advantages of a high boost ratio, flexible design, and simple control, the Y-Source Converter (YSC) is widely concerned. However, there are a few drawbacks to the traditional Y-source converter, including significant switching stress, voltage voltage overshoot, and discontinuous current. To solve the problems above, a series of improved topologies are proposed. Moreover, the voltage gain, current ripple, and soft switching characteristics have also been optimized. So far, the existing literature lacks the collation and comparison of different topologies of Y-source, as well as the analysis of its evolution process. Therefore, this paper provides a comprehensive overview of Y-source converters’ topologies. According to their features and applications, different topologies are classified and described, leading to guidance for the selection of YSCs under different scenarios. Meanwhile, the working principle, evolution process, and vital issues are analyzed. By revealing their deductive rules, valuable suggestions are provided for the future development of YSCs. Full article
20 pages, 10335 KiB  
Article
Pirfenidone Reverts Global DNA Hypomethylation, Promoting DNMT1/UHRF/PCNA Coupling Complex in Experimental Hepatocarcinoma
by Hipolito Otoniel Miranda-Roblero, Liliana Faridi Saavedra-Salazar, Marina Galicia-Moreno, Scarlet Arceo-Orozco, Fernando Caloca-Camarena, Ana Sandoval-Rodriguez, Jesús García-Bañuelos, Claudia Frias-Gonzalez, Mónica Almeida-López, Erika Martínez-López, Juan Armendariz-Borunda and Hugo Christian Monroy-Ramirez
Cells 2024, 13(12), 1013; https://doi.org/10.3390/cells13121013 (registering DOI) - 10 Jun 2024
Abstract
Hepatocellular carcinoma (HCC) development is associated with altered modifications in DNA methylation, changing transcriptional regulation. Emerging evidence indicates that DNA methyltransferase 1 (DNMT1) plays a key role in the carcinogenesis process. This study aimed to investigate how pirfenidone (PFD) modifies this pathway and [...] Read more.
Hepatocellular carcinoma (HCC) development is associated with altered modifications in DNA methylation, changing transcriptional regulation. Emerging evidence indicates that DNA methyltransferase 1 (DNMT1) plays a key role in the carcinogenesis process. This study aimed to investigate how pirfenidone (PFD) modifies this pathway and the effect generated by the association between c-Myc expression and DNMT1 activation. Rats F344 were used for HCC development using 50 mg/kg of diethylnitrosamine (DEN) and 25 mg/kg of 2-Acetylaminofluorene (2-AAF). The HCC/PFD group received simultaneous doses of 300 mg/kg of PFD. All treatments lasted 12 weeks. On the other hand, HepG2 cells were used to evaluate the effects of PFD in restoring DNA methylation in the presence of the inhibitor 5-Aza. Histopathological, biochemical, immunohistochemical, and western blot analysis were carried out and our findings showed that PFD treatment reduced the amount and size of tumors along with decreased Glipican-3, β-catenin, and c-Myc expression in nuclear fractions. Also, this treatment improved lipid metabolism by modulating PPARγ and SREBP1 signaling. Interestingly, PFD augmented DNMT1 and DNMT3a protein expression, which restores global methylation, both in our in vivo and in vitro models. In conclusion, our results suggest that PFD could slow down HCC development by controlling DNA methylation. Full article
(This article belongs to the Special Issue Cellular and Molecular Dysregulations of Solid Tumors)
Article
3D FRP Reinforcement Systems for Concrete Beams: Innovation towards High Performance Concrete Structures
by Handong Yan, Jiabao Zhao, Jianli Yin and Wei Sun
Materials 2024, 17(12), 2826; https://doi.org/10.3390/ma17122826 (registering DOI) - 10 Jun 2024
Abstract
Despite the advantages of using lightweight and non-corrosive carbon fiber reinforced polymer (CFRP) reinforcements in concrete structures, their widespread adoption has been limited due to concerns regarding the brittle failure of CFRP rupture and its relatively softer load-deflection stiffness. This work offers logical [...] Read more.
Despite the advantages of using lightweight and non-corrosive carbon fiber reinforced polymer (CFRP) reinforcements in concrete structures, their widespread adoption has been limited due to concerns regarding the brittle failure of CFRP rupture and its relatively softer load-deflection stiffness. This work offers logical solutions to these two crucial problems: using aggregate coating to strengthen the CFRP-concrete bond and ultimately the load-deflection stiffness, and using CFRP-concrete debonding propagation to create pseudo-ductile behavior. Subsequently, the concrete cracking behavior, the apparent CFRP modulus with aggregates, and the post-peak capacity and deflection of three-dimensional (3D) CFRP-reinforced concrete are all described by equations derived from experiments. These formulas will be helpful in the future design of non-prismatic concrete components for low-impact building projects. The potential of this innovative design scheme in terms of increased capacity and deflections with less concrete material is demonstrated through comparisons between non-prismatic CFRP-reinforced concrete and measured steel reinforced equivalency. Full article
(This article belongs to the Special Issue Structural Concrete and Composites: Processes, Corrosion and Modeling)
Review
The Seismic Evaluation of Existing Buildings for Energy Renovation—A Case Study for the Residential Building Stock in Bucharest (Romania)
by Florin Pavel and George Nica
Buildings 2024, 14(6), 1742; https://doi.org/10.3390/buildings14061742 (registering DOI) - 10 Jun 2024
Abstract
This study focuses on an overview of two programs applied to the residential building stock of Bucharest (Romania), namely, the seismic strengthening program and the thermal rehabilitation program. The methodology for seismic risk assessment given in the current generation of Romanian codes, as [...] Read more.
This study focuses on an overview of two programs applied to the residential building stock of Bucharest (Romania), namely, the seismic strengthening program and the thermal rehabilitation program. The methodology for seismic risk assessment given in the current generation of Romanian codes, as well as in previous regulations, is examined. A brief review of other seismic risk assessment methodologies currently applied in various seismically prone countries is also presented. Examples of high-rise buildings in Bucharest that suffered significant damage during the Vrancea 1977 earthquake and that were thermally rehabilitated without any strengthening works are shown in this paper. The consistent differences between the current outcomes of the two programs are presented and discussed. Finally, this review paper highlights the lack of coherence in terms of seismic risk assessments for the same class of buildings, inducing, in some situations, a false feeling of safety in the building inhabitants. In addition, a combined procedure for both seismic strengthening and thermal rehabilitation is mandatory, considering the seismicity of Romania, as well as ongoing climate change. Full article
(This article belongs to the Special Issue Innovative Solutions for Enhancing Seismic Resilience of Buildings)
17 pages, 5267 KiB  
Article
Mixing Performance of a Passive Micromixer Based on Split-to-Circulate (STC) Flow Characteristics
by Makhsuda Juraeva and Dong-Jin Kang
Micromachines 2024, 15(6), 773; https://doi.org/10.3390/mi15060773 (registering DOI) - 10 Jun 2024
Abstract
We propose a novel passive micromixer leveraging STC (split-to-circulate) flow characteristics and analyze its mixing performance comprehensively. Three distinct designs incorporating submerged circular walls were explored to achieve STC flow characteristics, facilitating flow along a convex surface and flow impingement on a concave [...] Read more.
We propose a novel passive micromixer leveraging STC (split-to-circulate) flow characteristics and analyze its mixing performance comprehensively. Three distinct designs incorporating submerged circular walls were explored to achieve STC flow characteristics, facilitating flow along a convex surface and flow impingement on a concave surface. Across a broad Reynolds number range (0.1 to 80), the present micromixer substantially enhances mixing, with a degree of mixing (DOM) consistently exceeding 0.84. Particularly, the mixing enhancement is prominent within the low and intermediate range of Reynolds numbers (0.1<Re<20). This enhancement stems from key flow characteristics of STC: the formation of saddle points around convex walls and flow impingement on concave walls. Compared to other passive micromixers, the DOM of the present micromixer stands out as notably high over a broad range of Reynolds numbers (0.1Re80). Full article
(This article belongs to the Special Issue Microreactors and Their Applications)
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Article
An Efficient and Eco-Friendly Procedure for Electrophilic Thiocyanation of Anilines and 1-(Substituted benzylidene)-2-phenyl Hydrazines
by A. M. M. Mallikarjunaswamy, Gouthami Kuruvalli, Khajamohiddin Syed, Vaddi Damodara Reddy and Vipin A. Nair
Chemistry 2024, 6(3), 476-488; https://doi.org/10.3390/chemistry6030027 (registering DOI) - 10 Jun 2024
Abstract
Thiocyanates form an important class of organic compounds commonly found in natural products that exhibit excellent antimicrobial activity. The electrophilic thiocyanation is one of the most effective methods of introducing a -SCN functional group to the parent organic molecule. In this work, we [...] Read more.
Thiocyanates form an important class of organic compounds commonly found in natural products that exhibit excellent antimicrobial activity. The electrophilic thiocyanation is one of the most effective methods of introducing a -SCN functional group to the parent organic molecule. In this work, we explored an eco-friendly and highly efficient method for thiocyanation of anilines and 1-(substituted benzylidene)-2-phenylhydrazines using commercially available N-bromoscuccinimide (NBS) and potassium thiocyanate (KSCN). The optimized protocol afforded thiocyanates with good regioselectivity and excellent yields in comparison to the available methods. Full article
(This article belongs to the Section Green and Environmental Chemistry)
19 pages, 1184 KiB  
Article
GNN-Based Network Traffic Analysis for the Detection of Sequential Attacks in IoT
by Tanzeela Altaf, Xu Wang, Wei Ni, Guangsheng Yu, Ren Ping Liu and Robin Braun
Electronics 2024, 13(12), 2274; https://doi.org/10.3390/electronics13122274 (registering DOI) - 10 Jun 2024
Abstract
This research introduces a novel framework utilizing a sequential gated graph convolutional neural network (GGCN) designed specifically for botnet detection within Internet of Things (IoT) network environments. By capitalizing on the strengths of graph neural networks (GNNs) to represent network traffic as complex [...] Read more.
This research introduces a novel framework utilizing a sequential gated graph convolutional neural network (GGCN) designed specifically for botnet detection within Internet of Things (IoT) network environments. By capitalizing on the strengths of graph neural networks (GNNs) to represent network traffic as complex graph structures, our approach adeptly handles the temporal dynamics inherent to botnet attacks. Key to our approach is the development of a time-stamped multi-edge graph structure that uncovers subtle temporal patterns and hidden relationships in network flows, critical for recognizing botnet behaviors. Moreover, our sequential graph learning framework incorporates time-sequenced edges and multi-edged structures into a two-layered gated graph model, which is optimized with specialized message-passing layers and aggregation functions to address the challenges of time-series traffic data effectively. Our comparative analysis with the state of the art reveals that our sequential gated graph convolutional neural network achieves substantial improvements in detecting IoT botnets. The proposed GGCN model consistently outperforms the conventional model, achieving improvements in accuracy ranging from marginal to substantial—0.01% for BoT IoT and up to 25% for Mirai. Moreover, our empirical analysis underscores the GGCN’s enhanced capabilities, particularly in binary classification tasks, on imbalanced datasets. These findings highlight the model’s ability to effectively navigate and manage the varying complexity and characteristics of IoT security threats across different datasets. Full article
(This article belongs to the Collection Graph Machine Learning)
24 pages, 4203 KiB  
Article
Shaping Sustainable Futures: Public Policies and Renewable Energy Insights Based on Global Bibliometric Analysis
by Armenia Androniceanu, Cristina Veith, Ștefan Alexandru Ionescu, Paul Marinescu, Alexandra Georgiana Sima and Alexandru Paru
Sustainability 2024, 16(12), 4957; https://doi.org/10.3390/su16124957 (registering DOI) - 10 Jun 2024
Abstract
The paradigm of sustainable energy is gaining ground at the historical juncture of the present worldwide push for sustainable development. This is being driven by the latest technological advancements and by a maturing process of public policy evolution toward support for a sustainable [...] Read more.
The paradigm of sustainable energy is gaining ground at the historical juncture of the present worldwide push for sustainable development. This is being driven by the latest technological advancements and by a maturing process of public policy evolution toward support for a sustainable energy transition. This paper analyzes, with the support of bibliometric analysis, the specialized literature in order to capture the main themes of interest, as well as their evolution, thus offering a panoramic view of research trends and the significance of implementing correct environmental measures and policies. Covering the period from 1991 to 2024, our exploration filters 2990 articles from the Web of Science database using a query that intersects “sustainable energy”, “renewable energy”, and “sustainable development”, with a nuanced consideration of the political landscape that shapes these domains. Using the advanced capabilities of the R program, the methodology employed facilitates a nuanced workflow of extraction and analysis, allowing for a detailed examination of the proliferation of research over the decades. This paper provides significant results, demonstrating the increasing impact of research through international collaborations, the importance of high-impact journals on sustainability policies, and the growing focus on “renewable energy” and “CO2 emissions”. The analysis of the relevance of term groups in environmental policy development and the correlation between economic growth and CO2 emissions confirms emerging trends. Furthermore, critical directions for future research and the necessity for formulating and implementing coherent sustainability policies are highlighted. Full article
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12 pages, 2683 KiB  
Article
Retrospective Correlation of the Circulation Time of Test Bolus Injections in MR Angiography and Cardiac Function
by David F. Möller, Borut Mohorko, Theresia E. Aschauer, Tobias Schwager and Manuela A. Aschauer
J. Vasc. Dis. 2024, 3(2), 212-223; https://doi.org/10.3390/jvd3020017 (registering DOI) - 10 Jun 2024
Abstract
This retrospective study examines 248 test bolus examinations preceding contrast-enhanced magnetic resonance angiography (CE-MRA) to extract clinically relevant data for critical limb ischemia (CLI) management. The method involved a retrospective review of test bolus exams, analysing 60 graphs for time to peak (TTP), [...] Read more.
This retrospective study examines 248 test bolus examinations preceding contrast-enhanced magnetic resonance angiography (CE-MRA) to extract clinically relevant data for critical limb ischemia (CLI) management. The method involved a retrospective review of test bolus exams, analysing 60 graphs for time to peak (TTP), full-width half-maximum (FWHM) time, and time to continual rise in signal intensity. These values were correlated with heart function parameters (ejection fraction, ASA classification, Lee index, and MET score). The results indicate a mean TTP of 31.2 ± 7.3 s, showing a correlation between the ejection fraction and ASA classification. Patients with atrial fibrillation exhibited prolonged TTP compared to those without. Despite population heterogeneity, these findings facilitate risk stratification for limb-saving interventions in CLI. TTP emerges as a potential clinical cardiovascular parameter and a risk factor for vascular interventions. Given the variation in injection protocols across centres, this study underscores the importance of precise bolus arrival time documentation for future multicentre studies. Full article
(This article belongs to the Section Peripheral Vascular Diseases)
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Article
Mullite 3D Printed Humidity Sensors
by Yurii Milovanov, Arianna Bertero, Bartolomeo Coppola, Paola Palmero and Jean-Marc Tulliani
Ceramics 2024, 7(2), 807-820; https://doi.org/10.3390/ceramics7020053 (registering DOI) - 10 Jun 2024
Abstract
Mullite substrates with two different porosities were 3D printed, and tested as humidity sensors. To evaluate the effects of porosity on humidity sensitivity, the samples were sintered at 1400 °C (Sensor 1) and 1450 °C (Sensor 2). The sensors were tested in a [...] Read more.
Mullite substrates with two different porosities were 3D printed, and tested as humidity sensors. To evaluate the effects of porosity on humidity sensitivity, the samples were sintered at 1400 °C (Sensor 1) and 1450 °C (Sensor 2). The sensors were tested in a range from 0% to 85% relative humidity (RH) at room temperature. When exposed to water vapor at room temperature, the impedance value dropped down from 155 MΩ under dry air to 480 kΩ under 85 RH% for Sensor 1 and from 115 MΩ under dry air to 410 kΩ for Sensor 2. In addition, response time and recovery time were below 2 min, whatever the firing temperature, when RH changed from 0% to 74%. Finally, tests carried out involving ammonia, methane, carbon dioxide and nitrogenous oxide, as well as ethanol and acetone, showed no interference. Full article
(This article belongs to the Special Issue Innovative Manufacturing Processes of Silicate Materials)
18 pages, 6129 KiB  
Article
OptimalNN: A Neural Network Architecture to Monitor Chemical Contamination in Cancer Alley
by Uchechukwu Leo Udeji and Martin Margala
J. Low Power Electron. Appl. 2024, 14(2), 33; https://doi.org/10.3390/jlpea14020033 (registering DOI) - 10 Jun 2024
Abstract
The detrimental impact of toxic chemicals, gas, and oil spills in aquatic environments poses a severe threat to plants, animals, and human life. Regions such as Cancer Alley exemplify the profound consequences of inadequately controlled chemical spills, significantly affecting the local community. Given [...] Read more.
The detrimental impact of toxic chemicals, gas, and oil spills in aquatic environments poses a severe threat to plants, animals, and human life. Regions such as Cancer Alley exemplify the profound consequences of inadequately controlled chemical spills, significantly affecting the local community. Given the far-reaching effects of these spills, it has become imperative to devise an efficient method for early monitoring, estimation, and cleanup, utilizing affordable and effective techniques. In this research, we explore the application of U-shaped neural Network (UNET) and U-shaped neural network transformer (UNETR) neural network models designed for the image segmentation of chemical and oil spills. Our models undergo training using the Commonwealth Scientific and Industrial Research Organization (CSIRO) dataset and the Oil Spill Detection dataset, employing a specialized filtering technique to enhance detection accuracy. We achieved training accuracies of 95.35% and 91% by applying UNET on the Oil Spill and the CSIRO datasets after 50 epochs of training, respectively. We also achieved a training accuracy of 75% by applying UNETR to the Oil Spill dataset. Additionally, we integrated mixed precision to expedite the model training process, thus maximizing data throughput. To further accelerate our implementation, we propose the utilization of the Field Programmable Gate Array (FPGA) architecture. The results obtained from our study demonstrate improvements in inference latency on FPGA. Full article
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23 pages, 4197 KiB  
Article
Urban Traffic Dominance: A Dynamic Assessment Using Multi-Source Data in Shanghai
by Yuyang Mei, Shenmin Wang, Mengjie Gong and Jiazheng Chen
Sustainability 2024, 16(12), 4956; https://doi.org/10.3390/su16124956 (registering DOI) - 10 Jun 2024
Abstract
This study redefines the evaluation of urban traffic dominance by integrating complex network theory with multi-source spatiotemporal trajectory data, addressing the dynamic nature of various transportation modes, including public transit and shared mobility. Traditional traffic studies, which focus predominantly on static road traffic [...] Read more.
This study redefines the evaluation of urban traffic dominance by integrating complex network theory with multi-source spatiotemporal trajectory data, addressing the dynamic nature of various transportation modes, including public transit and shared mobility. Traditional traffic studies, which focus predominantly on static road traffic characteristics, overlook the fluid dynamics integral to urban transport systems. We introduce Relative Weighted Centrality (RWC) as a novel metric for quantifying dynamic traffic dominance, combining it with traditional static metrics to forge a comprehensive traffic dominance evaluation system. The results show the following: (1) Both static and dynamic traffic dominance display core-periphery structures centered around Huangpu District. (2) Dynamically, distinct variations in RWC emerge across different times and transport modes; during the early hours (0:00–6:00), shared bicycles show unique spatial distributions, the subway network experiences a notable decrease in RWC yet maintains its spatial pattern, and taxis exhibit intermediate characteristics. Conversely, the RWC for all modes generally increases during morning (6:00–12:00) and evening (18:00–24:00) peaks, with a pronounced decrease in subway RWC in the latter period. (3) The integration of dynamic evaluations significantly modifies conventional static results, emphasizing the impact of population movements on traffic dominance. This comprehensive analysis provides crucial insights into the strategic management and development of urban traffic infrastructure in Shanghai. Full article
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21 pages, 334 KiB  
Article
Gravitational Wormholes
by Mengqi Lu, Jiayue Yang and Robert B. Mann
Universe 2024, 10(6), 257; https://doi.org/10.3390/universe10060257 (registering DOI) - 10 Jun 2024
Abstract
Spacetime wormholes are evidently an essential component of the construction of a time machine. Within the context of general relativity, such objects require, for their formation, exotic matter—matter that violates at least one of the standard energy conditions. Here, we explore the possibility [...] Read more.
Spacetime wormholes are evidently an essential component of the construction of a time machine. Within the context of general relativity, such objects require, for their formation, exotic matter—matter that violates at least one of the standard energy conditions. Here, we explore the possibility that higher-curvature gravity theories might permit the construction of a wormhole without any matter at all. In particular, we consider the simplest form of a generalized quasi topological theory in four spacetime dimensions, known as Einsteinian Cubic Gravity. This theory has a number of promising features that make it an interesting phenomenological competitor to general relativity, including having non-hairy generalizations of the Schwarzschild black hole and linearized equations of second order around maximally symmetric backgrounds. By matching series solutions near the horizon and at large distances, we find evidence that strong asymptotically AdS wormhole solutions can be constructed, with strong curvature effects ensuring that the wormhole throat can exist. Full article
(This article belongs to the Special Issue The Physics of Time Travel)
20 pages, 631 KiB  
Article
A Hybrid Genetic Algorithm for Ground Station Scheduling Problems
by Longzeng Xu, Changhong Yu, Bin Wu and Ming Gao
Appl. Sci. 2024, 14(12), 5045; https://doi.org/10.3390/app14125045 (registering DOI) - 10 Jun 2024
Abstract
In recent years, the substantial growth in satellite data transmission tasks and volume, coupled with the limited availability of ground station hardware resources, has exacerbated conflicts among missions and rendered traditional scheduling algorithms inadequate. To address this challenge, this paper introduces an improved [...] Read more.
In recent years, the substantial growth in satellite data transmission tasks and volume, coupled with the limited availability of ground station hardware resources, has exacerbated conflicts among missions and rendered traditional scheduling algorithms inadequate. To address this challenge, this paper introduces an improved tabu genetic hybrid algorithm (ITGA) integrated with heuristic rules for the first time. Firstly, a constraint satisfaction model for satellite data transmission tasks is established, considering multiple factors such as task execution windows, satellite–ground visibility, and ground station capabilities. Leveraging heuristic rules, an initial population of high-fitness chromosomes is selected for iterative refinement. Secondly, the proposed hybrid algorithm iteratively evolves this population towards optimal solutions. Finally, the scheduling plan with the highest fitness value is selected as the best strategy. Comparative simulation experimental results demonstrate that, across four distinct scenarios, our algorithm achieves improvements in the average task success rate ranging from 1.5% to 19.8% compared to alternative methods. Moreover, it reduces the average algorithm execution time by 0.5 s to 28.46 s and enhances algorithm stability by 0.8% to 27.7%. This research contributes a novel approach to the efficient scheduling of satellite data transmission tasks. Full article
(This article belongs to the Section Aerospace Science and Engineering)

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