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  • MDPI AG  (100)
  • 1
    Online Resource
    Online Resource
    Metabolites from Bacillus subtilis J-15 Affect Seedling Growth of Arabidopsis thaliana and Cotton Plants
    MDPI AG ; 2022
    In:  Plants Vol. 11, No. 23 ( 2022-11-23), p. 3205-
    Details
    In: Plants, MDPI AG, Vol. 11, No. 23 ( 2022-11-23), p. 3205-
    Abstract: Bacillus subtilis J-15 is a plant growth-promoting rhizobacteria isolated from the soil rhizosphere of cotton and is resistant to cotton verticillium wilt. This study evaluated the effects of metabolites of J-15 (J-15-Ms), including mycosubtilin, on plant growth using Arabidopsis and cotton plants. The results showed that J-15-Ms promoted Arabidopsis seeding growth at lower concentrations of 0.2 μg/mL but inhibited the growth at higher concentrations, such as 20 μg/mL. Similar results were obtained in cotton. Thus, J-15-Ms-treated plants showed low-concentration-induced growth promotion and high-concentration-induced growth inhibition. The J-15-Ms components were analyzed by liquid chromatography–mass spectrometry. Correlation analysis using the J-15 genomic databases suggested that J-15 may synthesize indoleacetic acid via the indole-3-pymvate pathway and indole-3-acetamide pathway. Treatment with mycosubtilin, a purified peptide from J-15-Ms, showed that the peptide promoted Arabidopsis growth at a low concentration (0.1 μg/mL) and inhibited plant growth at high concentrations (higher than 1 μg/mL), which also significantly increased plant lateral root number. Transcriptomic analysis showed that mycosubtilin might promote lateral root development and inhibit plant primary root growth by regulating the expression of the plant hormone signaling pathway. This study reveals the mechanism of Bacillus subtilis J-15 in affecting plant growth.
    Type of Medium: Online Resource
    ISSN: 2223-7747
    URL: Article
    DOI: 10.3390/plants11233205
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704341-1
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  • 2
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    Online Resource
    Characterization of Phage vB_SalM_SPJ41 and the Reduction of Risk of Antibiotic-Resistant Salmonella enterica Contamination in Two Ready-to-Eat Foods
    MDPI AG ; 2023
    In:  Antibiotics Vol. 12, No. 2 ( 2023-02-09), p. 364-
    Details
    In: Antibiotics, MDPI AG, Vol. 12, No. 2 ( 2023-02-09), p. 364-
    Abstract: Salmonella enterica is a major cause of foodborne illness, and the emergence of antibiotic-resistant bacteria has led to huge pressures on public health. Phage is a promising strategy for controlling foodborne pathogens. In this study, a novel Salmonella phage vB_SalM_SPJ41 was isolated from poultry farms in Shanghai, China. Phage vB_SalM_SPJ41 was able to lyse multiple serotypes of antibiotic-resistant S. enterica, including S. Enteritidis, S. Typhimurium, S. Shubra, S. Derby, and S. Nchanga. It had a short incubation period and was still active at a temperature 〈 80 °C and in the pH range of 3~11. The phage can effectively inhibit the growth of S. enterica in liquid culture and has a significant inhibitory and destructive effect on the biofilm produced by antibiotic-resistant S. enterica. Moreover, the phage was able to reduce S. Enteritidis and MDR S. Derby in lettuce to below the detection limit at 4 °C. Furthermore, the phage could reduce S. Enteritidis and S. Derby in salmon below the limit of detection at 4 °C, and by 3.9 log10 CFU/g and· 2.1 log10 CFU/g at 15 °C, respectively. In addition, the genomic analysis revealed that the phages did not carry any virulence factor genes or antibiotic resistance genes. Therefore, it was found that vB_SalM_SPJ41 is a promising candidate phage for biocontrol against antibiotic-resistant Salmonella in ready-to-eat foods.
    Type of Medium: Online Resource
    ISSN: 2079-6382
    URL: Article
    DOI: 10.3390/antibiotics12020364
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2681345-2
    SSG: 15,3
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  • 3
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    A Simple Scheme for Photonic Generation of Microwave Waveforms Using a Dual-drive Mach–Zehnder Modulator
    MDPI AG ; 2020
    In:  Applied Sciences Vol. 10, No. 21 ( 2020-11-08), p. 7914-
    Details
    In: Applied Sciences, MDPI AG, Vol. 10, No. 21 ( 2020-11-08), p. 7914-
    Abstract: In this paper, a novel photonic scheme for the generation of square and triangular waveforms is proposed and experimentally demonstrated by using a dual-drive Mach–Zehnder modulator (DDMZM) without any optical signal processing. By properly setting the modulation index of the DDMZM, the square and triangular microwave waveforms could be easily achieved in conjunction with a 90° hybrid coupler. Furthermore, the modulation index of the DDMZM could be tuned for a low radio frequency (RF) signal power requirement by tuning the phase difference of the RF signals applied to the two arms of the DDMZM. The proposed scheme for the photonic generation of microwave waveforms is theoretically analyzed and experimentally demonstrated. The periodical triangular and square waveforms with repetition rates of 5 GHz, 8 GHz, and 10 GHz are successfully obtained. The root-mean-square errors between the generated and theoretical triangular and square waveforms with a repetition of 5 GHz are 0.042 and 0.053, respectively.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app10217914
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704225-X
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  • 4
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    Transcriptomic Profiling of Tomato Leaves Identifies Novel Transcription Factors Responding to Dehydration Stress
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 11 ( 2023-06-03), p. 9725-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 11 ( 2023-06-03), p. 9725-
    Abstract: Drought is among the most challenging environmental restrictions to tomatoes (Solanum lycopersi-cum), which causes dehydration of the tissues and results in massive loss of yield. Breeding for dehydration-tolerant tomatoes is a pressing issue as a result of global climate change that leads to increased duration and frequency of droughts. However, the key genes involved in dehydration response and tolerance in tomato are not widely known, and genes that can be targeted for dehydration-tolerant tomato breeding remains to be discovered. Here, we compared phenotypes and transcriptomic profiles of tomato leaves between control and dehydration conditions. We show that dehydration decreased the relative water content of tomato leaves after 2 h of dehydration treatment; however, it promoted the malondialdehyde (MDA) content and ion leakage ratio after 4 h and 12 h of dehydration, respectively. Moreover, dehydration stress triggered oxidative stress as we detected significant increases in H2O2 and O2− levels. Simultaneously, dehydration enhanced the activities of antioxidant enzymes including peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and phenylalanine ammonia-lyase (PAL). Genome-wide RNA sequencing of tomato leaves treated with or without dehydration (control) identified 8116 and 5670 differentially expressed genes (DEGs) after 2 h and 4 h of dehydration, respectively. These DEGs included genes involved in translation, photosynthesis, stress response, and cytoplasmic translation. We then focused specifically on DEGs annotated as transcription factors (TFs). RNA-seq analysis identified 742 TFs as DEGs by comparing samples dehydrated for 2 h with 0 h control, while among all the DEGs detected after 4 h of dehydration, only 499 of them were TFs. Furthermore, we performed real-time quantitative PCR analyses and validated expression patterns of 31 differentially expressed TFs of NAC, AP2/ERF, MYB, bHLH, bZIP, WRKY, and HB families. In addition, the transcriptomic data revealed that expression levels of six drought-responsive marker genes were upregulated by de-hydration treatment. Collectively, our findings not only provide a solid foundation for further functional characterization of dehydration-responsive TFs in tomatoes but may also benefit the improvement of dehydration/drought tolerance in tomatoes in the future.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms24119725
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 5
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    Online Resource
    Prediction Model for Daily Reference Crop Evapotranspiration Based on Hybrid Algorithm in Semi-Arid Regions of China
    MDPI AG ; 2022
    In:  Atmosphere Vol. 13, No. 6 ( 2022-06-06), p. 922-
    Details
    In: Atmosphere, MDPI AG, Vol. 13, No. 6 ( 2022-06-06), p. 922-
    Abstract: The accurate estimation of reference crop evapotranspiration (ETO) plays an important role in guiding regional water resource management and crop water content research. In order to improve the accuracy of ETO prediction in regions with missing data, this study used the partial correlation analysis method to select factors that have a large impact on ETO as input combinations to construct ETO estimation models for typical stations in semi-arid regions of China. A biological heuristic optimization algorithm (Golden Eagle optimization algorithm (GEO) and Sparrow optimization algorithm (SSA)) and Extreme Learning Machine model (ELM) were combined to improve the estimation accuracy. The results showed that Ra was the primary factor affecting the ETO model, with an importance range of 0.187–0.566. Compared with the independent ELM model, the hybrid model has higher accuracy and stability. The estimated value of the SSA-ELM model under five-factor input condition (Ra, RH, Tmax, Tmin, U2) is closest to the standard value calculated by FAO56 PM: RMSE = 0.067–0.085, R2 = 0.998–0.999, MAE = 0.050–0.066 and NSE = 0.998–0.999. In general, the combination of a partial correlation analysis algorithm and a hybrid model can be used to estimate ETO with high accuracy under the condition of reducing input factors. Use of the first five factors extracted from the partial correlation analysis algorithm as input to build an ETO estimation model based on SSA-ELM in China’s semi-arid regions is recommended, which can also provide a reference for ETO estimation in similar regions.
    Type of Medium: Online Resource
    ISSN: 2073-4433
    URL: Article
    DOI: 10.3390/atmos13060922
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2605928-9
    SSG: 23
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  • 6
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    Optically-Injected-Semiconductor-Laser-Based Tunable Dual-Frequency Optoelectronic Oscillator under Subharmonic Microwave Modulation
    MDPI AG ; 2021
    In:  Applied Sciences Vol. 11, No. 9 ( 2021-04-27), p. 3961-
    Details
    In: Applied Sciences, MDPI AG, Vol. 11, No. 9 ( 2021-04-27), p. 3961-
    Abstract: To obtain low-phase-noise microwave signals with a widely tunable frequency range, an optoelectronic oscillator (OEO) was constructed on the basis of an optically injected semiconductor laser (OISL) for the generation of high-quality microwave signals. Our OEO relied on the effect of wavelength-selective amplification and the period-one (P1) oscillation under optical injection. The signal’s frequency stability, side-mode-suppression ratio (SMSR) and linewidth were optimized by the subharmonic microwave modulation technique in the OEO loop. The experimental results showed that the frequency of the signal obtained by the proposed OEO could be tuned up to 18 GHz. Using the dual-loop OEO structure, the SMSR was increased to 55 dB. Moreover, the phase noise of the obtained microwave signal was lower than −81 dBc/Hz at 1 kHz frequency offset and −119 dBc/Hz at 10 kHz frequency offset. This was achieved by introducing subharmonic microwave modulation in the OEO loop, respectively. Furthermore, via the utilization of a Fabry–Perot laser diode (FP-LD) in the proposed structure, a dual-loop OEO with different dual-frequency configurations (which could be tuned up to 12 and 18 GHz) was obtained.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app11093961
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2704225-X
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  • 7
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    A Tunable Dual-Passband Microwave Photonic Filter Based on Optically Injected Distributed Feedback Semiconductor Lasers and Dual-Output Mach-Zehnder Modulator
    MDPI AG ; 2020
    In:  Applied Sciences Vol. 10, No. 10 ( 2020-05-24), p. 3631-
    Details
    In: Applied Sciences, MDPI AG, Vol. 10, No. 10 ( 2020-05-24), p. 3631-
    Abstract: In this paper, a novel approach to achieving a wideband tunable dual-passband microwave photonic filter (MPF) is proposed based on optical-injected distributed feedback (DFB) semiconductor lasers and a dual-output Mach–Zehnder modulator (DOMZM). The fundamental concepts for realizing the MPF are the wavelength-selective amplification effect and the period-one oscillation state under optically injected DFB lasers. These effects provide a widely tunable range of center frequency, along with high flexibility and low insertion loss. The proposed MPF is experimentally demonstrated, showing that the dual-passband center frequency in the MPF can be tuned independently from 19 to 37 GHz by adjusting the detuning frequency and injection ratio. Meanwhile, the insertion loss of the system is about 15 dB when there is no optical or electrical amplifier in the MPF link. The out-of-band suppression ratio of the MPF is more than 20 dB, which can be improved by adjusting the power of the two optical signals.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app10103631
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704225-X
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  • 8
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    Chemical Characterization and Genesis of Thermal Reservoir Water in the Southern Part of the Jizhong Depression
    MDPI AG ; 2023
    In:  Water Vol. 15, No. 20 ( 2023-10-10), p. 3532-
    Details
    In: Water, MDPI AG, Vol. 15, No. 20 ( 2023-10-10), p. 3532-
    Abstract: The Jizhong Depression is a typical Mesozoic and Cenozoic fault basin located in the northwestern part of the Bohai Bay Basin that has abundant hydrothermal and geothermal resources and enormous development potential. In this study, hydrochemical and isotopic analyses were conducted on water samples from the southern region of the Jizhong Depression. The formation and evolution processes of the deep geothermal water were analyzed, the circulation process of the deep geothermal water was determined, and the genetic mechanism of the geothermal systems was elucidated. The hydrochemical types of the geothermal fluids in the sandstone reservoirs in the research area are mainly Cl·HCO3−Na type, while the geothermal fluids in the carbonate reservoirs are mainly Cl-Na type and Cl·HCO3−Na type. The ion components in the geothermal water are mainly controlled by the dissolution of the carbonate rocks and the alternate adsorption of cations. The elevation of the geothermal water supply area is 763–1063 m, and the main source is precipitation from the mountainous areas in the western Taihang Mountains. The Na-K-Ca temperature scale and multi-mineral equilibrium method have relatively small errors and are suitable for the southern region of the Jizhong Depression, with average errors of 21.44 °C and 32.64 °C, respectively. The depth of the Jxw thermal storage cycle in the research area is 3033–5187 m, and the depth of the Ng thermal storage cycle is 1360–2862 m. The content of the main ions (Na+, K+, and Cl−) in the water samples of the study area is greater in the Jxw thermal storage than in the Ng thermal storage; the Jxw thermal storage water samples have lower γNa+/γCl− values than the Ng thermal storage; and the γSO42−/γCl− and γCl−/(γHCO3− + CO32−) values are greater than those of the Ng thermal storage, indicating that the Jxw thermal storage is located in a geological environment with better sealing, longer flow, slower water circulation, more complete leaching, and higher salinity than the Ng thermal storage. Part of the deep thermal storage is transmitted upwards through the rocks via thermal conduction, and part is transmitted upwards along fault channels via thermal convection, forming a convection–conduction-type geothermal system.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    URL: Article
    DOI: 10.3390/w15203532
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2521238-2
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  • 9
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    Influence of Environmental Factors on the Site Selection and Layout of Ancient Military Towns (Zhejiang Region)
    MDPI AG ; 2022
    In:  Sustainability Vol. 14, No. 5 ( 2022-02-23), p. 2572-
    Details
    In: Sustainability, MDPI AG, Vol. 14, No. 5 ( 2022-02-23), p. 2572-
    Abstract: There are many subjective inferences regarding environment-related studies in modern studies of ancient military defense heritage, and the objective quantitative analysis of citadel site selection and layout has become the key to interpreting the environmental adaptability of citadels under defense strategies. Based on this, it has been proposed in this research that the site selection of ancient military citadels in a specific region (Zhejiang) has environmental adaptability characteristics. Firstly, an elevated hydrological overlay model was established by predicting and graphically verifying the ancient hydrological thresholds through geospatial analysis strategies. Secondly, the hydrological and topographical indicators of the regional environment where the military citadel is located were digitally extracted. Finally, correlation and weight influence calculations were performed for different environmental data. The environmental adaptability characteristics of the site layout of the Ming dynasty-era Zhejiang coastal defense military citadel, based on military defense needs, were obtained. In this way, we promote digital technology for the excavation, conservation and sustainable use of heritage resources.
    Type of Medium: Online Resource
    ISSN: 2071-1050
    URL: Article
    DOI: 10.3390/su14052572
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2518383-7
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  • 10
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    Study on the Motion Characteristics of Particles Transported by a Horizontal Pipeline in Heterogeneous Flow
    MDPI AG ; 2022
    In:  Water Vol. 14, No. 19 ( 2022-10-09), p. 3177-
    Details
    In: Water, MDPI AG, Vol. 14, No. 19 ( 2022-10-09), p. 3177-
    Abstract: The worldwide problem of reservoir sedimentation has perplexed the water conservancy industry. The problem of reservoir sedimentation is particularly serious in sandy rivers in China and directly affects the normal function of reservoirs. Due to its effect on the economy and environmental protection, the self-priming pipeline dredging and sediment discharge technology has broad application prospects. Nevertheless, there are pressing problems in the transportation of slurry particles in the pipeline system of this new technology. The purpose of this study is to use physical model tests to analyze the influence of the sediment transport rate and pipeline velocity on the motion state of particles (aggregation transport, jump transport, and suspension transport) when a heterogeneous flow with different particle sizes is transported in the pipeline. The results indicate that under the same pipeline velocity and sediment transport rate, the thickness of the static particle accumulation layer decreases with the increase in particle size in the state of aggregation and transportation, and the smaller the particle size, the greater the particle movement speed in the case of aggregation and suspension transportation. During jump transportation, the velocity of particles above the critical inflection point Y’ increases with the decrease in particle size. The opposite is found below the critical inflection point Y’. At the same particle size and sediment transport rate, when the pipeline velocity increases, the particle transport transits from aggregation transport to jump transport and then to suspension transport. The larger the pipeline velocity, the greater the overall movement speed of particles. When gathering and conveying, if the pipeline flow rate increases by 1.5, the maximum movement speed of particles increases by 3.3. The curvature of the vertical velocity curve of the particles during jump transportation is not affected by the pipeline velocity. The particle velocity at the highest point increases with the increase in the pipeline velocity. During suspension transportation, the difference between the maximum and minimum vertical particle distribution velocities is exponentially related to the pipeline velocity. At the same pipe velocity and particle size, the overall particle velocity decreases with the increase in sediment transport rate.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    URL: Article
    DOI: 10.3390/w14193177
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2521238-2
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