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  • MDPI AG  (17)
  • 1
    Online Resource
    Online Resource
    An Overview of Light-Mediated Impact of Graphene Oxide on Algae: Photo-Transform, Toxicity and Mechanism
    MDPI AG ; 2022
    In:  Water Vol. 14, No. 19 ( 2022-09-23), p. 2997-
    Details
    In: Water, MDPI AG, Vol. 14, No. 19 ( 2022-09-23), p. 2997-
    Abstract: Due to the unique chemical and physical properties, graphene-based nanomaterials are increasingly being introduced into various scientific fields. They all play very important roles in different fields and are widely used. Graphene oxide (GO) is one of the most popular and representative carbon nanomaterials; scientists have great research interest in it. When carbon nanomaterials such as GO are released into the aquatic environment, their physicochemical properties will be influenced by natural light, resulting in the potential change in toxic effects on aquatic organisms. Algae, as a typical aquatic organism, is extensively regarded as a model microorganism to assess the biotoxicity of nanomaterials. In this review, we overview the light-mediated impact of GO on algae. We summarize the photo-transformation of GO under different illumination conditions and the effect of illumination on the physicochemical properties of GO. Then, we combined metabolomics, genotoxicity, and proteomics with standard toxicity assays (cell division, membrane permeability, oxidative stress, photosynthesis, cellular ultrastructure, and so on) to compare native and environmentally transformed GO induction toxicological mechanisms. By correlating lights, physicochemical properties, and biotoxicity, this review is valuable for environmental fate assessments on graphene-based nanoparticles, providing a theoretical basis and support for evaluating the potential ecological health and environmental risks of graphene-based nanoparticles in real natural water environments.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    URL: Article
    DOI: 10.3390/w14192997
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2521238-2
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  • 2
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    Failure Mechanism of the Yizhuxiang Collapse under the Joint Effect of Freeze–Thaw and Mining
    MDPI AG ; 2023
    In:  Applied Sciences Vol. 13, No. 6 ( 2023-03-16), p. 3801-
    Details
    In: Applied Sciences, MDPI AG, Vol. 13, No. 6 ( 2023-03-16), p. 3801-
    Abstract: At 10:05 a.m. on 4 February 2022, the perilous rock mass Yizhuxiang in Leizu Town, Yuan’an County, Hubei Province, China collapsed on a large scale. The Yizhuxiang collapse was about 35 m in length, 52 m in height, and 29 m in maximum thickness. The volume of the collapse was 5.32 × 104 m3. It threatened the transport of the national trunk road, destroyed the branch road and some cement mixing station workshops, and caused serious economic losses. The rock mass exposed in the collapse was dolomite with developed joint fractures. Under the effects of mining and unloading, fractures occurred in the rock mass; the top of the rock mass was bent and deformed towards the free face; and tension cracks were formed on the rear edge. The safety ore pillar directly below the collapsed body was compressed and deformed under the action of gravity, thus accelerating the internal deformation of the rock mass and leading to the formation of multiple dominant joints inside the rock mass. In the winter of 2021, the weather was extreme, with heavy snowfall and low temperatures. Under the effects of freeze–thaw, the strength of the rock mass declined and the tension cracks further expanded so that the rock mass experienced an accelerated deformation and finally collapsed. Causes of the collapse include mining activity beneath the collapsed mass and heightened extreme weather. The cause of the landslide disaster in this area is, however, freeze–thaw, which deserves the attention of scholars and the vigilance of the local government.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app13063801
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2704225-X
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  • 3
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    Substituent Effects of the Nitrogen Heterocycle on Indole and Quinoline HDN Performance: A Combination of Experiments and Theoretical Study
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 3 ( 2023-02-03), p. 3044-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 3 ( 2023-02-03), p. 3044-
    Abstract: Hydrodenitrogenation (HDN) experiments and density functional theory (DFT) calculations were combined herein to study the substituent effects of the nitrogen heterocycle on the HDN behaviors of indole and quinoline. Indole (IND), 2-methyl-indole (2-M-IND), 3-methyl-indole (3-M-IND), quinoline (QL), 2-methyl-quinoline (2-M-QL) and 3-methyl-quinoline (3-M-QL) were used as the HDN reactant on the NiMo/γ-Al2O3 catalyst. Some key elementary reactions in the HDN process of these nitrogen compounds on the Ni-Mo-S active nanocluster were calculated. The notable difference between IND and QL in the HDN is that dihydro-indole (DHI) can directly convert to O-ethyl aniline via the C–N bond cleavage, whereas tetrahydro-quinoline (THQ) can only break the C–N single bond via the full hydrogenation saturation of the aromatic ring. The reason for this is that the –NH and C=C groups of DHI can be coplanar and well adsorbed on the Ni-Mo-edge simultaneously during the C–N bond cleavage. In comparison, those of THQ cannot stably simultaneously adsorb on the Ni-Mo-edge because of the non-coplanarity. Whenever the methyl group locates on the α-C or the β-C atom of indole, the hydrogenation ability of the nitrogen heterocycle will be evidently weakened because the methyl group increases the space requirement of the sp3 carbon, and the impaction of the C=C groups on the Ni-S-edge cannot provide enough space. When the methyl groups are located on the α-C of quinoline, the self-HDN behavior of 2-M-QL is similar to quinoline, whereas the competitive HDN ability of 2-M-QL in the homologs is evidently weakened because the methyl group on the α-C hinders the contact between the N atom of 2-M-QL and the exposed metal atom of the coordinatively unsaturated active sites (CUS). When the methyl group locates on the β-C of quinoline, the C–N bond cleavage of 3-methyl-quinoline becomes more difficult because the methyl group on the β-C increases the steric hindrance of the C=C group. However, the competitive HDN ability of 3-M-QL is not evidently influenced because the methyl group on the β-C does not evidently hinder the adsorption of 3-M-QL on the active sites.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms24033044
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 4
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    N-Acetylcysteine Enhances the Recovery of Ischemic Limb in Type-2 Diabetic Mice
    MDPI AG ; 2022
    In:  Antioxidants Vol. 11, No. 6 ( 2022-05-31), p. 1097-
    Details
    In: Antioxidants, MDPI AG, Vol. 11, No. 6 ( 2022-05-31), p. 1097-
    Abstract: Critical limb ischemia (CLI) is a severe complication of diabetes mellitus that occurs without effective therapy. Excessive reactive oxygen species (ROS) production and oxidative stress play critical roles in the development of diabetic cardiovascular complications. N-acetylcysteine (NAC) reduces ischemia-induced ROS production. The present study aimed to investigate the effect of NAC on the recovery of ischemic limb in an experimental model of type-2 diabetes. TALLYHO/JngJ diabetic and SWR/J non-diabetic mice were used for developing a CLI model. For NAC treatment, mice received NAC (1 mg/mL) in their drinking water for 24 h before initiating CLI, and continuously for the duration of the experiment. Blood flow, mechanical function, histology, expression of antioxidant enzymes including superoxide dismutase (SOD)-1, SOD-3, glutathione peroxidase (Gpx)-1, catalase, and phosphorylated insulin receptor substrate (IRS)-1, Akt, and eNOS in ischemic limb were evaluated in vivo or ex vivo. Body weight, blood glucose, plasma advanced glycation end-products (AGEs), plasma insulin, insulin resistance index, and plasma TNF-a were also evaluated during the experiment. NAC treatment effectively attenuated ROS production with preserved expressions of SOD-1, Gpx-1, catalase, phosphorylated Akt, and eNOS, and enhanced the recovery of blood flow and function of the diabetic ischemic limb. NAC treatment also significantly decreased the levels of phosphorylated IRS-1 (Ser307) expression and plasma TNF-α in diabetic mice without significant changes in blood glucose and AGEs levels. In conclusion, NAC treatment enhanced the recovery of blood flow and mechanical function in ischemic limbs in T2D mice in association with improved tissue redox/inflammatory status and insulin resistance.
    Type of Medium: Online Resource
    ISSN: 2076-3921
    URL: Article
    DOI: 10.3390/antiox11061097
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704216-9
    SSG: 15,3
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  • 5
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    Development and Validation of a Novel Prognostic Tool to Predict Recurrence of Paroxysmal Atrial Fibrillation after the First-Time Catheter Ablation: A Retrospective Cohort Study
    MDPI AG ; 2023
    In:  Diagnostics Vol. 13, No. 6 ( 2023-03-22), p. 1207-
    Details
    In: Diagnostics, MDPI AG, Vol. 13, No. 6 ( 2023-03-22), p. 1207-
    Abstract: There is no gold standard to tell frustrating outcomes after the catheter ablation of paroxysmal atrial fibrillation (PAF). The study aims to construct a prognostic tool. We retrospectively analyzed 315 patients with PAF who underwent first-time ablation at the Second Xiangya Hospital of Central South University. The endpoint was identified as any documented relapse of atrial tachyarrhythmia lasting longer than 30 s after the three-month blanking period. Univariate Cox regression analyzed eleven preablation parameters, followed by two supervised machine learning algorithms and stepwise regression to construct a nomogram internally validated. Five factors related to ablation failure were as follows: female sex, left atrial appendage emptying flow velocity ≤31 cm/s, estimated glomerular filtration rate 〈 65.8 mL/(min·1.73 m2), P wave duration in lead aVF ≥ 120 ms, and that in lead V1 ≥ 100 ms, which constructed a nomogram. It was correlated with the CHA2DS2-VASc score but outperformed the latter evidently in discrimination and clinical utility, not to mention its robust performances in goodness-of-fit and calibration. In addition, the nomogram-based risk stratification could effectively separate ablation outcomes. Patients at risk of relapse after PAF ablation can be recognized at baseline using the proposed five-factor nomogram.
    Type of Medium: Online Resource
    ISSN: 2075-4418
    URL: Article
    DOI: 10.3390/diagnostics13061207
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2662336-5
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  • 6
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    Deeper Insights into the Effect of Humic Acid on Kitchen Waste Anaerobic Digestion: Enzyme Activities, Microbial Community Dynamics, and Key Metabolic Pathways
    MDPI AG ; 2023
    In:  Fermentation Vol. 9, No. 10 ( 2023-09-29), p. 881-
    Details
    In: Fermentation, MDPI AG, Vol. 9, No. 10 ( 2023-09-29), p. 881-
    Abstract: Anaerobic digestion (AD) represents one of the most eco-friendly approaches for recovering the energy from kitchen waste (KW). This study investigated the impact of humic acid (HA) on AD of KW. Batch experiments were conducted using KW as the substrate, with varying HA dosages. The results revealed that an increase in HA dosage led to an inhibition of methanogenic efficiency by 29.51% and a delayed start-up of AD. The HA exhibited dual effects on enzyme activities during AD, inhibiting hydrolytic enzymes while stimulating acidogenic enzymes. This unique interaction ultimately resulted in a significant 12.32% increase in volatile fatty acid production. Furthermore, HA induced the generation of reactive oxygen species and had a discernible impact on the activity of the electron transfer system. A bioinformatics analysis highlighted that HA promoted the abundance of microorganisms with mediated interspecies electron transfer ability, including DMER64 and Methanosaeta, as well as the Firmicutes phylum, while significantly reducing the abundance of Methanobacterium. Moreover, the KEGG pathway analysis revealed a decrease in hydrolysis and methanogenesis-related genes and an increase in acidogenesis-related genes.
    Type of Medium: Online Resource
    ISSN: 2311-5637
    URL: Article
    DOI: 10.3390/fermentation9100881
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2813985-9
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  • 7
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    The Control of the Expansion or Compression of Colloidal Crystals Lattice with Salt Solution
    MDPI AG ; 2024
    In:  Nanomaterials Vol. 14, No. 4 ( 2024-02-13), p. 355-
    Details
    In: Nanomaterials, MDPI AG, Vol. 14, No. 4 ( 2024-02-13), p. 355-
    Abstract: Tuning the lattice spacing or stop bands holds great significance in the design and application of materials with colloidal crystals. Typically, particle surface modifications or the application of external physical fields are needed. In this study, we demonstrated the ability to expand or compress the lattice of colloidal crystals simply by utilizing a salt solution, without the need for any special treatments to the colloidal particles. We found that by only considering the diffusiophoresis effect we cannot explain the reversion of lattice expansion to lattice compression with the increase in the salt concentration and that the diffusioosmotic flow originating from the container wall must be taken into account. Further analysis revealed that variations in the salt concentration altered the relative amplitudes between diffusiophoresis and diffusioosmosis through changing the zeta potentials of the particles and the wall, and the competition between the particle diffusiophoresis and wall diffusioosmosis lay at the center of the underlying mechanism.
    Type of Medium: Online Resource
    ISSN: 2079-4991
    URL: Article
    DOI: 10.3390/nano14040355
    Language: English
    Publisher: MDPI AG
    Publication Date: 2024
    detail.hit.zdb_id: 2662255-5
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  • 8
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    Colocated MIMO Radar Waveform-Array Joint Optimization for Sparse Array
    MDPI AG ; 2023
    In:  Sensors Vol. 23, No. 9 ( 2023-04-28), p. 4375-
    Details
    In: Sensors, MDPI AG, Vol. 23, No. 9 ( 2023-04-28), p. 4375-
    Abstract: Colocated multiple-input multiple-output (MIMO) radar can transmit a group of distinct waveforms via its colocated transmit antennas and the waveform diversity leads to several advantages in contrast to conventional phased-array radar. The performance depends highly on the degrees available, and element spacing can be deemed as another source of degrees of freedom. In this paper, we study the joint waveform and element spacing optimization problem. A joint waveform and array optimization criterion is proposed to match the transmit beampattern, the suppression range, and the angular sidelobes, under the constraints of minimal element spacing and total array aperture. Meanwhile, the effect of receive beamforming on suppressing mutual correlation between returns from different spatial directions is also incorporated into the optimization criterion. The optimization problem is solved by the sequential quadratic programming algorithm. Numerical results indicate that with more degrees of freedom from array spacings, colocated MIMO radar achieves a better transmit beampattern matching performance and a lower sidelobe level, compared with a fixed half-wavelength spaced array, but the benefits from additional degrees of freedom from array spacing optimization have a limit.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s23094375
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2052857-7
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  • 9
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    Signal Source Positioning Based on Angle-Only Measurements in Passive Sensor Networks
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 4 ( 2022-02-17), p. 1554-
    Details
    In: Sensors, MDPI AG, Vol. 22, No. 4 ( 2022-02-17), p. 1554-
    Abstract: Some passive sensors can measure only directions of arrival of signals, but the real positions of signal sources are often desirable, which can be estimated by combining distributed passive sensors as a network. However, passive observations should be correctly associated first. This paper studies the multi-target data association and signal localization problem in distributed passive sensor networks. With angle-only measurements from distributed passive sensors, multiple lines in a 3-dimensional (3D) scenario can be built and then those that will intersect in a small volume in 3D are classified into the same source. The center of the small volume is taken as an estimate of the signal source position, whose statistical distributions are formulated. If the minimum distance is less than an association threshold, then two lines are considered to be from the same signal source. In numerical results, the impacts of angle measurement accuracy and platform self-positioning accuracy are analyzed, indicating that this method can achieve a prescribed data association rate and a high positioning performance with a low computation cost.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s22041554
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 10
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    Signal Source Localization with Long-Term Observations in Distributed Angle-Only Sensors
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 24 ( 2022-12-09), p. 9655-
    Details
    In: Sensors, MDPI AG, Vol. 22, No. 24 ( 2022-12-09), p. 9655-
    Abstract: Angle-only sensors cannot provide range information of targets and in order to determine accurate position of a signal source, one can connect distributed passive sensors with communication links and implement a fusion algorithm to estimate target position. To measure moving targets with sensors on moving platforms, most of existing algorithms resort to the filtering method. In this paper, we present two fusion algorithms to estimate both the position and velocity of moving target with distributed angle-only sensors in motion. The first algorithm is termed as the gross least square (LS) algorithm, which takes all observations from distributed sensors together to form an estimate of the position and velocity and thus needs a huge communication cost and a huge computation cost. The second algorithm is termed as the linear LS algorithm, which approximates locations of sensors, locations of targets, and angle-only measures for each sensor by linear models and thus does not need each local sensors to transmit raw data of angle-only observations, resulting in a lower communication cost between sensors and then a lower computation cost at the fusion center. Based on the second algorithm, a truncated LS algorithm, which estimates the target velocity through an average operation, is also presented. Numerical results indicate that the gross LS algorithm, without linear approximation operation, often benefits from more observations, whereas the linear LS algorithm and the truncated LS algorithm, both bear lower communication and computation costs, may endure performance loss if the observations are collected in a long period such that the linear approximation model becomes mismatch.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s22249655
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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