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1.
ACS Omega ; 9(9): 10769-10781, 2024 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-38463313

RESUMEN

Due to the low permeability and apparent mechanical anisotropy of shale reservoirs, shale oil production highly depends on the performance of hydraulic fracturing of the tight reservoir. Pre-injection of CO2 before hydraulic fracturing treatment has been proven beneficial to enhance shale oil production. A comprehensive understanding of the effect of changes in the properties of shale reservoirs after preinjected CO2 on the hydraulic fracturing behavior of shale reservoirs is essential to improve the stimulated reservoir volume (SRV) of shale oil reservoirs. In this study, comprehensive evaluating parameters were proposed to specify the variation of mechanical properties of shale rock at different soaking times of CO2 based on published testing parameters of shale. Accordingly, a three-dimensional (3D) numerical model was established and three groups of horizontal well fracturing cases with different cluster spacings were conducted based on the adaptive FE-DE method to simulate and compare the hydraulic fracturing behavior in the reservoirs with different mechanical properties. We established a quantitative relationship between the alterations in reservoir properties and the stimulated reservoir volume. The results indicate that both the brittleness and conductivity properties of shale rock are dramatically improved as the increment of soaking time of CO2. It is beneficial to improve the SRV, and the initiation pressure is reduced with the increment of soaking time of CO2. However, as the stress shadow effect is involved in the horizontal well fracturing, the complexity of the hydrofracturing crack is significantly enhanced to restrain the development of hydrofracturing crack. When the cluster spacing is larger, the stress shadow effect is weakened, and the weakening effect of CO2 soaking on reservoir is more obvious.

2.
J Agric Food Chem ; 72(6): 3142-3149, 2024 Feb 14.
Artículo en Inglés | MEDLINE | ID: mdl-38299554

RESUMEN

Peanut allergy is a prevalent and concerning food allergy. Roasting can introduce structural changes to peanut allergens, affecting their allergenicity, but the structure on the primary structure is unclear. Here, the breakage sites were identified by mass spectrometry and software tools, and structural changes were simulated by molecular dynamics and displayed by PyMOL software. Results revealed that the appearance frequencies of L, Q, F, and E were high at the N-terminal of the breakage site, while S and E were dominant at the C-terminal. In the conformational structure, breakage sites were found close to disulfide bonds and the Cupin domains of Ara h 1 and Ara h 3. The breakage of allergens destroyed linear epitopes and might change the conformation of epitopes, which could influence peanuts' potential allergenicity.


Asunto(s)
Arachis , Hipersensibilidad al Cacahuete , Arachis/química , Antígenos de Plantas/análisis , Alérgenos/química , Calor , Inmunoglobulina E , Epítopos , Espectrometría de Masas , Proteínas de Plantas/química
3.
Int J Biol Macromol ; 258(Pt 1): 128340, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38000575

RESUMEN

Interactions between plant polyphenols and food allergens may be a new way to alleviate food allergies. The non-covalent interactions between the major allergen from peanut (Ara h 2) with procyanidin dimer (PA2) were therefore characterized using spectroscopic, thermodynamic, and molecular simulation analyses. The main interaction between the Ara h 2 and PA2 was hydrogen bonding. PA2 statically quenched the intrinsic fluorescence intensity and altered the conformation of the Ara h 2, leading to a more disordered polypeptide structure with a lower surface hydrophobicity. In addition, the in vitro allergenicity of the Ara h 2-PA2 complex was investigated using enzyme-linked immunosorbent assay (ELISA) kits. The immunoglobulin E (IgE) binding capacity of Ara h 2, as well as the release of allergenic cytokines, decreased after interacting with PA2. When the ratio of Ara h 2-to-PA2 was 1:50, the IgE binding capacity was reduced by around 43 %. This study provides valuable insights into the non-covalent interactions between Ara h 2 and PA2, as well as the potential mechanism of action of the anti-allergic reaction caused by binding of the polyphenols to the allergens.


Asunto(s)
Hipersensibilidad al Cacahuete , Proantocianidinas , Arachis/química , Antígenos de Plantas/química , Alérgenos/química , Proantocianidinas/metabolismo , Glicoproteínas/química , Inmunoglobulina E/metabolismo , Polifenoles/metabolismo , Proteínas de Plantas/química
4.
Environ Sci Pollut Res Int ; 31(5): 7283-7297, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38155310

RESUMEN

As the world's greatest energy consumer, China's energy consumption and transition have become a focus of attention. The most significant location for regional integration in the north of China is the Beijing-Tianjin-Hebei region, where the industrial sector dominates its energy consumption. Forecasting the energy demand and structure of industrial sectors in China's Beijing-Tianjin-Hebei region may help to promote the energy transition and CO2 emission mitigation. This study conducts a model based on the year 2020 using the Long-Range Energy Alternatives Planning System (LEAP) software and sets two scenarios (baseline scenario and emission peak scenario) to forecast the future energy demand and CO2 emissions of industrial sectors in China's Beijing-Tianjin-Hebei region until the year 2035. Moreover, the industrial sectors are classified into traditional high-energy-consuming industries, emerging manufacturing industries, daily-related light industries, and other industries. The forecasting results show that (1) The industrial energy demand of the entire Beijing-Tianjin-Hebei region will grow from 234 Mtce in 2020 to 317 Mtce in 2035, and the corresponding energy structure will shift from coal-based to electricity-based; (2) at the provincial level, all three provinces will experience an increase in industrial energy demand between 2020 and 2035, with Hebei experiencing the fastest average annual growth rate of 2.18% and the largest share of over 80%, and Beijing experiencing the highest average annual electrification rate of 70%; (3) at the industrial sector level, the electricity and natural gas will gradually replace other energy sources as the main energy source for industry. The most representative industrial sub-sector in Beijing, Tianjin, and Hebei provinces are all traditional high-energy-consuming industries, which will account for more than 90% of the total energy demand in both Tianjin and Hebei by 2035.


Asunto(s)
Dióxido de Carbono , Industrias , China , Industria Manufacturera , Predicción
5.
Genes (Basel) ; 14(11)2023 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-38003041

RESUMEN

Teak is a rare tropical tree with high economic value, and it is one of the world's main afforestation trees. Low temperature is the main problem for introducing and planting this species in subtropical or temperate zones. Low-temperature acclimation can enhance the resistance of teak to low-temperature stress, but the mechanism for this is still unclear. We studied the gene expression of two-year-old teak seedlings under a rapid temperature drop from 20 °C to 4 °C using RNA-seq and WGCNA analyses. The leaves in the upper part of the plants developed chlorosis 3 h after the quick transition, and the grades of chlorosis were increased after 9 h, with the addition of water stains and necrotic spots. Meanwhile, the SOD and proline contents in teak leaves increased with the prolonged cold stress time. We also identified 36,901 differentially expressed genes, among which 1055 were novel. Notably, CBF2 and CBF4 were significantly induced by low temperatures, while CBF1 and CBF3 were not. Furthermore, WGCNA successfully identified a total of fourteen modules, which consist of three modules associated with cold stress response genes, two modules linked to CBF2 and CBF4, and one module correlated with the CBF-independent pathway gene HY5. The transformation experiments showed that TgCBF2 and TgCBF4 improved cold resistance in Arabidopsis plants.


Asunto(s)
Anemia Hipocrómica , Proteínas de Arabidopsis , Arabidopsis , Humanos , Preescolar , Temperatura , Proteínas de Arabidopsis/genética , Transcriptoma/genética , Frío , Arabidopsis/metabolismo , Transactivadores/genética
6.
Materials (Basel) ; 16(20)2023 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-37895765

RESUMEN

The aim of this paper is to investigate the mechanism of an electric current-assisted superplastic deformation on 3Y-TZP in an oxygen-lean atmosphere. The experiments were performed with different electric currents in the range of 0~5 A. The results show that the flow stress of 3Y-TZP during the deformation was significantly decreased by the combination of Joule heating and the applied current effect. The microstructures of the deformed specimens were all equiaxed grains without an obvious preferential grain growth. The stress exponent n = 2.05~2.61 suggested that the dominant deformation of 3Y-YZP with/without the electric current was grain boundary sliding at 1400 °C. The activation energy of the deformation which decreased from 465 kJ mol-1 to 315 kJ mol-1 by the electric current indicated that the lattice diffusion of Zr cation during the deformation was enhanced. And the deformation rate of 3Y-TZP with the electric current may be controlled by the grain boundary diffusion of Zr cation.

7.
Mater Horiz ; 10(8): 2854-2867, 2023 07 31.
Artículo en Inglés | MEDLINE | ID: mdl-37337916

RESUMEN

Silkworm silks show increasing potential in applications of bioengineering, sensors, optics, electronics, and actuators. However, their inherent irregular morphologies, structures, and properties greatly hinder the translation of these technologies to commercial applications. Herein, we report a facile and comprehensive strategy to fabricate high-performance silk materials by spinning silkworms artificially via a multi-task and high-efficiency centrifugal reeling technique. With this strategy, centrifugally reeled silks (CRSs) with long-uniform morphologies, excellent strength (844.83 ± 319.48 MPa), high toughness (121.07 ± 35.31 MJ m-3), and outstanding Young's modulus (27.72 ± 12.61 GPa) are developed. Remarkably, the maximum strength (1.45 GPa) of CRS is 3 times that of cocoon silk and even comparable to spider silk. Moreover, the centrifugal reeling technique realizes the one-step preparation of centrifugally reeled silk yarn (CRSY) from spinning silkworm, and the CRSYs show higher strength (877.38 ± 377.23 MPa) and superior torsional recovery performances. Furthermore, these CRSY-based soft pneumatic actuators (SPAs) exhibit light weight, high-loading capability, easy programmability in strength and motions, and fast responses, and therefore outperform currently reported elastomer-based SPAs, showing promising applications in flexible sensors, artificial muscles, and soft robotics. This work also provides a new guide for producing high-performance silks from silk-secreting insects and arthropods.


Asunto(s)
Bombyx , Seda , Animales , Seda/química , Bombyx/química , Módulo de Elasticidad , Bioingeniería , Ingeniería Biomédica
8.
Mult Scler Relat Disord ; 73: 104629, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36963169

RESUMEN

BACKGROUND: Music Therapy (MT) is a unique treatment method for Persons with Multiple Sclerosis (PwMS) that can accelerate their functional recovery. MT has been proven to adjust the gait performance of PwMS in a short period. Its therapeutic effects in gait disorders of PwMS for long-term intervention are also starting to draw interest, but it has yet to be investigated. AIM: This review aimed to systematically examine the outcomes of PwMS with gait disorders after receiving MT intervention. METHODS: A systematic review has been performed using several academic databases with keywords such as music therapy, multiple sclerosis, and gait. The study protocol was registered on PROSPERO (CRD42022365668). RESULTS: A total of 405 studies were initially identified. After applying the inclusion and exclusion criteria, twelve studies were finally included. The results showed that all PwMS received MT intervention with different strategies, and ten studies confirmed that gait disorders of PwMS were effectively improved by MT intervention. CONCLUSION: Most previous studies focused on the transient effects of MT on the gait performance of PwMS. This review bridges gaps in the long-term intervention of MT on gait disorders of PwMS and offers references for therapists to design treatment plans. According to this review, MT intervention has positive therapeutic effects on gait disorders in PwMS.


Asunto(s)
Trastornos Neurológicos de la Marcha , Trastornos del Movimiento , Esclerosis Múltiple , Musicoterapia , Música , Humanos , Esclerosis Múltiple/complicaciones , Esclerosis Múltiple/terapia , Marcha , Trastornos Neurológicos de la Marcha/etiología , Trastornos Neurológicos de la Marcha/terapia
9.
Materials (Basel) ; 16(4)2023 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-36837370

RESUMEN

Copper and its alloys are used widely in marine environments, and anisotropic corrosion influences the corrosion kinetics of copper. Corrosion of copper in an electrolyte containing Cl- is described as a dissolution-deposition process, which is a prolonged process. Therefore, it is laborious to clarify the corrosion anisotropy in different stages. In this paper, electrochemical impedance spectroscopy (EIS) following elapsed open circuit potential (OCP) test with 0 h (0H), 24 h (24H) and 10 days (10D) was adopted. To exclude interruptions such as grain boundary and neighbor effect, single crystal (SC) Cu(100) and Cu(111) were employed. After 10D OCP, cross-sectional slices were cut and picked up by a focused ion beam (FIB). The results showed that the deposited oxide was Cu2O and Cu(100)/Cu(111) experienced different corrosion behaviors. In general, Cu(100) showed more excellent corrosion resistance. Combined with equivalent electrical circuit (EEC) diagrams, the corrosion mechanism of Cu(100)/Cu(111) in different stages was proposed. In the initial stage, a smaller capacitive loop of Cu(111) suggested preferential adsorption of Cl- on air-formed oxide film on Cu(111). Deposited oxide and exposed bare metals also played an important role in corrosion resistance. Rectangle indentations and pyramidal structures formed on Cu(100)/Cu(111), respectively. Finally, a perfect interface on Cu(100) explained the tremendous capacitive loop and higher impedance (14,274 Ω·cm2). Moreover, defects in the oxides on Cu(111) provided channels for the penetration of electrolyte, leading to a lower impedance (9423 Ω·cm2) after 10D corrosion.

10.
Plant Cell Rep ; 42(5): 859-877, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36788135

RESUMEN

SINA (Seven in absentia) proteins in the subtype of E3 ubiquitin ligase family play a crucial role in plant growth and development. However, their functions in response to salt and osmotic stresses in oil crops are still largely unknown. In this study, a total number of 23 BnaSINAs were identified in the rapeseed genome. Chromosome location and collinear relationship analyses revealed that they were unevenly distributed on 13 chromosomes, and have gone through 22 segmental duplication events under purifying selection. Phylogenetic and gene structural analyses indicated that they belonged to five main groups, and those in the same subgroup showed similar gene structure. All BnaSINAs were predicted to form homo- or heterodimers. Except BnaSINA7, BnaSINA11, BnaSINA17 and BnaSINA18, which lacked the N-terminal RING finger, all BnaSINAs contained a conserved C-terminal SINA domain, a typical structural feature of the RING-type E3 ligase family. Transcriptional expression analyses demonstrated that most BnaSINAs were ubiquitously expressed in roots, stems, leaves, flowers, pods and seeds, and all were responsive to salt and osmotic stresses. Further, yeast two-hybrid and Arabidopsis mutant complementation analyses demonstrated that BnaSINA4 interacted with BnaSINA17 to form heterodimer, and expression of BnaSINA17 in the Arabidopsis sina2 mutant restored its growth resistance to salt and osmotic stresses. Our findings provide an important genetic foundation for the functional elucidation of BnaSINAs and a novel gene resource for the breeding of new oil crop cultivars with improved abiotic stress resistance.


Asunto(s)
Arabidopsis , Brassica napus , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Arabidopsis/genética , Brassica napus/genética , Brassica napus/metabolismo , Presión Osmótica , Ubiquitina/genética , Ubiquitina/metabolismo , Filogenia , Fitomejoramiento , Cloruro de Sodio/farmacología , Cloruro de Sodio/metabolismo , Estrés Fisiológico/genética , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/metabolismo
11.
Materials (Basel) ; 15(23)2022 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-36500082

RESUMEN

The effect of shot peen forming on the corrosion-resistant of 2024 aluminum alloy in a salt spray environment was studied with an electrochemical workstation. The surface morphology and cross sectional morphology of the original and shot peen-formed sample were studied by a scanning electron microscope. After shot peen forming, the salt spray corrosion resistance of 2024 aluminum alloy was worsened (the corrosion rates of the original alloy and the shot peen-formed alloy were 0.10467 mg/(cm2·h) and 0.27333 mg/(cm2·h), respectively, when the salt spray corrosion time was 5 h). The radius of capacitive reactance arc of the sample subjected to shot peen forming was smaller than that of the original sample. When the salt spray corrosion time was 5 h, the doping density (NA) of the original alloy was 2.5128 × 10-13/cm3. After shot peen forming, the NA of the alloy increased to 15 × 10-13/cm3. For the shot peen-formed sample, pitting corrosion first occurred in the crater lap zone and became severe with salt spray time. The cross sectional morphology of both original and the shot peen-formed samples shows that severe intergranular corrosion occurred in the salt spray environment. However, for the original sample, the intergranular corrosion distribution was lamellar. For shot peen-formed sample, the intergranular corrosion distribution was network.

12.
Rev. psicol. deport ; 31(3)Oct 16, 2022. ilus, tab
Artículo en Inglés | IBECS | ID: ibc-214718

RESUMEN

Due to the imperfection of community facilities, the linkage effect of the traditional community promotion model decreases. Therefore, a community linkage promotion model of children's physical health management is designed. Extracting the influencing factors of community linkage of children's physical health management, analyzing the feasibility of community linkage. Then realizing the community linkage promotion model. Comparative experiment is adopted to verify that the community linkage effect of the new model is better, and it has great promotion value.(AU)


Asunto(s)
Humanos , Masculino , Femenino , Niño , Salud Infantil , Instituciones Académicas , Crecimiento , Deportes
13.
Colloids Surf B Biointerfaces ; 218: 112756, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35988312

RESUMEN

High efficiency of in-situ cross-linking and acid triggered drug delivery is realized by introducing tobramycin into the hydrogels. Injectable and biodegradable hydrogels are prepared through two steps: First generation of reactive aldehyde groups in the sodium alginate (A-Alg) and then introduction of antibiotic tobramycin as cross-linker. Due to the formation of dynamic Schiff base bonds between the amino groups in tobramycin and aldehyde groups in A-Alg, the gelation of hydrogels can be realized immediately. Thus, tobramycin acts well as the first role cross-linker and the hydrogels containing tobramycin can be injected into the wound during the treatment. In addition, the acid from the decomposition of organic compounds by the bacteria can break the cross-linking points previously formed by tobramycin in the hydrogels. Therefore, tobramycin can be released and act as the second role model drug to kill the bacteria. Because the hydrogels network is broken, the release of tobramycin is more efficient than the traditional drug delivery from hydrogels by diffusion. Based on these unique properties, the present hydrogels containing tobramycin exhibit a good injectable and biodegradable capability. In addition, due to the existence of the reversible acid-labile linkages in the hydrogels, the hydrogels containing tobramycin are also self-healing, which additionally is favorable for the application of wound dressing. More importantly, the antibacterial hydrogels also demonstrate good biocompatibility in vitro and significantly therapeutic effects on an infected mice model in vivo. Based on the above special properties, the hydrogels cross-linked by tobramycin indicate a new approach to prepare hydrogel dressings with low-cost, non-toxicity and good anti-bacterial performance in the treatment of infectious wounds.


Asunto(s)
Hidrogeles , Tobramicina , Aldehídos , Alginatos/química , Animales , Antibacterianos/química , Antibacterianos/farmacología , Hidrogeles/química , Ratones , Bases de Schiff/química , Tobramicina/farmacología
14.
Front Pediatr ; 10: 910566, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35859945

RESUMEN

Background: Accurate bilirubin measurements are essential for appropriate management of neonatal hyperbilirubinemia. This study aimed to evaluate the accuracy and reliability of whole blood bilirubin measurements obtained using a Roche blood gas analyzer (Roche TBiL), with total serum bilirubin (TSB) measurements determined by the Ortho VITROS 4600 chemistry system (Ortho TSB) serving as a reference. Materials and Methods: Medical records of hospitalized neonates that underwent simultaneous Roche TBiL and Ortho TSB measurements were reviewed for eligibility selection and data collection. The correlations and differences between two sets of results were determined using Passing-Bablok regression analysis and a Bland-Altman plot, respectively. For eligible newborns, the risk of developing severe hyperbilirubinemia was assessed using the Bhutani nomogram. Weighted kappa analysis was used to evaluate the agreement between risk prediction by the two methods. Results: We obtained 618 paired Roche TBiL and Ortho TSB results from 309 neonates. Roche TBiL and Ortho TSB measurements showed a good correlation (r = 0.923; 95% CI: 0.905-0.938). Passing-Bablok regression analysis yielded the following equation: Roche TBiL = 0.794 × Ortho TSB + 1.255 mg/dL, with a slope of 0.794 (95% CI: 0.763-0.825) and intercept of 1.255 (95% CI: 1.042-1.417). The average difference between the two methods was 0.1 ± 1.448 mg/dL. A total of 207 neonates were eligible for evaluation of the agreement between the risk-grading methods. Although kappa analysis showed good agreement between the methods, with a weighted kappa of 0.681 (95% CI: 0.610-0.751) across all populations, the values for approximately half of the neonates at intermediate and high risk of hyperbilirubinemia (33/72) were underestimated by Roche TBiL. Conclusion: Our results indicate that Roche TBiL and Ortho TSB measurements in the neonatal population are not consistent. As a point-of-care and trace blood assay, Roche blood gas bilirubin measurements can facilitate primary screening of neonatal hyperbilirubinemia, but it seems to lack accuracy regarding risk stratification, particularly for high-risk newborn individuals.

15.
Materials (Basel) ; 15(6)2022 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-35329520

RESUMEN

Natural brown cotton has favorable antibacterial and antioxidant properties. In this study, we explored the effect of gauze made from natural brown cotton after scouring and bleaching on wound healing in rats. In this work, a control experiment was adopted. The control group used absorbent cotton gauze, and the experimental group utilized natural brown cotton bleached gauze. The materials were applied to rat models to explore the effects of the two dressings on wound healing. By analyzing the wound healing state of rats, calculating the healing rate, and combining the pathological HE staining, Masson staining, and CD31 immunohistochemical staining, the results showed that both gauzes have positive effects on the wound healing of the rats. Moreover, compared with the control group, the wound healing rate of rats in the experimental group increased by 14.81%, the number of inflammatory cells decreased by 12.93%, the number of new blood vessels increased by 6.88%, the growth rate of the granulation tissue area was 10.76%, the step-up rate of the area occupied by collagen was 33.71%, and the increase rate of optical density value was 10.00%. This study found that natural brown cotton bleached gauze has a better effect on wound healing than ordinary absorbent cotton gauze, and can be used as medical dressings.

16.
Nanoscale ; 13(42): 17837-17845, 2021 Nov 04.
Artículo en Inglés | MEDLINE | ID: mdl-34668896

RESUMEN

Carbon materials are highly promising electrode materials for supercapacitors, due to their hierarchical porous structure and large specific surface area. However, the limited specific capacitance and inferior rate capability significantly prevent their practical application. Herein, 3D interconnected hierarchical porous carbon aerogels (CNFAs) through engineering the pyrolysis chemistry of CNF are developed. The obtained CNFAs effectively improve the carbon yield and suppress the volume shrinkage, as well as have robust mechanical properties. As a supercapacitor electrode, the CNFAs-17% electrode exhibits an ultrahigh capacitance of 440.29 F g-1 at 1 A g-1, significantly superior to most reported biomass-based carbon materials. Moreover, the CNFAs-17% assembled symmetric supercapacitor (SSC) achieves an outstanding rate capability (63.29% at 10 mA cm-2), high areal energy density (0.081 mWh cm-2), and remarkable cycling stability (nearly 100% capacitance retention after 7000 cycles). This work offers a simple, effective strategy towards the preparation of promising electrode materials for high-performance energy storage applications.

17.
J Anim Ecol ; 90(7): 1647-1654, 2021 07.
Artículo en Inglés | MEDLINE | ID: mdl-33724452

RESUMEN

Rare plant species often suffer less damage than common species because of positive density-dependent herbivory, and it has been suggested that this 'rare species advantage' fosters plant species coexistence. However, it is unknown whether rare species have an advantage when pollination interactions are also considered. We hypothesized that a 'positive density-dependent pollination success' across plant species would result in common plants experiencing higher seed set rates compared to rare species, and that positive density-dependent effects would negate or even override the positive density-dependent damage due to herbivory resulting in higher seed loss rates in common plant species. We tested this hypothesis by concurrently examining a plant-predispersal seed predator system and a plant-pollinator system for 24 Asteraceae species growing in an alpine meadow community (Sichuan Province, China). Having previously reported a positive density-dependent effect on seed loss rates due to seed predators, we here focus on the density-dependent effects on pollination success by investigating pollinator species richness, visitation frequencies and seed set rates for each plant species. We also estimated the seed output rate of each plant species as the product of seed set rate and the rate of surviving seeds (i.e. 1 - the seed loss rate). Consistent with our hypothesis, a positive density-dependent effect was observed for pollinator species richness, visitation frequencies and seed set rates across plant species. Moreover, the positive effect overrode the negative density-dependent effect of herbivores on seed production, such that common species tended to have a higher seed output rate than rare species (i.e. we observed a 'rare species disadvantage'). These results indicate that the low seed output rate of rare species might result from a pollination limitation, and that both mutualistic and antagonistic interactions should be examined simultaneously to fully understand plant species coexistence in local communities.


Asunto(s)
Asteraceae , Polinización , Animales , China , Flores , Pradera , Herbivoria , Semillas
18.
J Anim Ecol ; 90(4): 846-858, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33340098

RESUMEN

Studies show that plant defenses influence the host-use of herbivores and tend to be evolutionarily more labile than herbivore traits (e.g. feeding preferences). However, all previous studies have focused exclusively on non-volatile plant defenses thereby overlooking the roles of plant volatiles. We hypothesized that volatiles are equally important determinants of herbivore host-use and are evolutionarily more labile than herbivore traits. To test these hypotheses, the following experiments were conducted. We identified the volatiles and non-volatiles of 17 Asteraceae species and measured their relative contents. We also used a highly resolved bipartite trophic network of the 17 host species and 20 herbivorous (pre-dispersal seed predator) tephritid fly species to determine the evolutionary interactions between plants and herbivores. The chemical data showed that interspecific similarity in volatiles-but not non-volatiles and phylogenetic distance-significantly accounted for the herbivore community across the plant species; this implies that plant volatiles-but not non-volatile compounds and species identity-dictate plant-tephritid fly interactions. Moreover, we observed phylogenetic signal for non-volatiles but not for volatiles; therefore closely related herbivores do not necessarily use closely related host species with similar non-volatiles, but do tend to attack plants producing similar volatiles. Thus, plant volatiles are evolutionarily more labile than non-volatiles and herbivore traits associate with host use. These results show that the interactions between plants and herbivores are evolutionary asymmetric, shed light on the role of plant volatiles in plant-herbivore interactions, and highlight the need to include data for both volatiles and non-volatiles when investigating plant-animal interactions.


Asunto(s)
Dípteros , Compuestos Orgánicos Volátiles , Animales , Evolución Biológica , Herbivoria , Interacciones Huésped-Parásitos , Filogenia
19.
Front Plant Sci ; 11: 534703, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33013961

RESUMEN

Climate warming is often seasonally asymmetric with a higher temperature increase toward winters than summers. However, the effect of winter-biased warming on plant reproductive phenology has been seldom investigated under natural field conditions. The goal of this study was to determine the effects of winter-biased warming on plant reproductive phenologies. In an alpine meadow of Tibetan Plateau, we deployed six large (15 m × 15 m × 2.5 m height) open top chambers (three warmed chambers and three non-warmed chambers) to achieve winter-biased warming (i.e., a small increase in annual mean temperature with a greater increase towards winter than summer). We investigated three phenophases (onset and offset times and duration) for both the flowering and fruiting phenologies of 11 common species in 2017 and 8 species in 2018. According to the vernalization theory, we hypothesized that mild winter-biased warming would delay flowering and fruiting phenologies. The data indicated that the phenological responses to warming were species-specific (including positive, neutral, and negative responses), and the number of plant species advancing flowering (by averagely 4.5 days) and fruiting onset times (by averagely 3.6 days) was higher than those delaying the times. These changes were inconsistent with the vernalization hypothesis (i.e. plants need to achieve a threshold of chilling before flowering) alone, but can be partly explained by the accumulated temperature hypothesis (i.e. plants need to achieve a threshold of accumulative temperature before flowering) and/or the overtopping hypothesis (i.e. plants need to reach community canopy layer before flowering). The interspecific difference in the response of reproductive phenology could be attributed to the variation in plant traits including plant height growth, the biomass ratio of root to shoot, and seed mass. These results indicate that a mild winter-biased warming may trigger significant change in plant reproductive phenology in an alpine meadow.

20.
Nat Mater ; 19(9): 999-1005, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32541934

RESUMEN

Dielectric ceramics are highly desired for electronic systems owing to their fast discharge speed and excellent fatigue resistance. However, the low energy density resulting from the low breakdown electric field leads to inferior volumetric efficiency, which is the main challenge for practical applications of dielectric ceramics. Here, we propose a strategy to increase the breakdown electric field and thus enhance the energy storage density of polycrystalline ceramics by controlling grain orientation. We fabricated high-quality <111>-textured Na0.5Bi0.5TiO3-Sr0.7Bi0.2TiO3 (NBT-SBT) ceramics, in which the strain induced by the electric field is substantially lowered, leading to a reduced failure probability and improved Weibull breakdown strength, on the order of 103 MV m-1, an ~65% enhancement compared to their randomly oriented counterparts. The recoverable energy density of <111>-textured NBT-SBT multilayer ceramics is up to 21.5 J cm-3, outperforming state-of-the-art dielectric ceramics. The present research offers a route for designing dielectric ceramics with enhanced breakdown strength, which is expected to benefit a wide range of applications of dielectric ceramics for which high breakdown strength is required, such as high-voltage capacitors and electrocaloric solid-state cooling devices.

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