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2.
J Environ Manage ; 300: 113798, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34562819

RESUMO

The resuspension and sedimentation of particulate matter and the release of nutrients from sediment are important factors affecting the eutrophication of shallow lakes. The capture and removal of particles rich in nitrogen, phosphorus, and other nutrients at the bottom of lakes is of great significance for improving the management and eutrophication status of lakes. This study investigated the feasibility of applying lake bottom trap technology in seven different locations in Lake Chaohu, which is the fifth largest freshwater lake in China. The results showed that the trap in the western part of Lake Chaohu had the highest sedimentation rate and could capture most of the nutrients. The sedimentation rates were higher in spring and summer than in autumn and winter. The bottom trap effectively collected and preserved chlorophyll a, organic matter, total nitrogen, and total phosphorus. The trap per meter length (15-20 m wide) could catch 20.7-27.6 m3 of particles rich in nutrients with a water content of 50-70%, organic matter content of 281.9-375.8 kg, total nitrogen content of 24.5-32.6 kg, and total phosphorus content of 10.5-14 kg. The proposed bottom trap had little impact on the benthic organism system of the lake. The bottom trap technology used in this study could solve the problem of nitrogen, phosphorus, and algae accumulation in lakes and reservoirs, broaden the utility of lake hydrodynamics in environmental pollution control, and provide new ideas and strategies for the control and management of cumulative pollution in shallow lakes and reservoirs.


Assuntos
Sedimentos Geológicos , Lagos , China , Clorofila A , Monitoramento Ambiental , Eutrofização , Nitrogênio/análise , Nutrientes , Fósforo/análise , Tecnologia
3.
Adv Mater ; 33(45): e2106175, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34561930

RESUMO

Liquid crystal elastomers (LCEs) are a class of soft active materials of increasing interest, because of their excellent actuation and optical performances. While LCEs show biomimetic mechanical properties (e.g., elastic modulus and strength) that can be matched with those of soft biological tissues, their biointegrated applications have been rarely explored, in part, due to their high actuation temperatures (typically above 60 °C) and low biaxial actuation performances (e.g., actuation strain typically below 10%). Here, unique mechanics-guided designs and fabrication schemes of LCE metamaterials are developed that allow access to unprecedented biaxial actuation strain (-53%) and biaxial coefficient of thermal expansion (-33 125 ppm K-1 ), significantly surpassing those (e.g., -20% and -5950 ppm K-1 ) reported previously. A low-temperature synthesis method with use of optimized composition ratios enables LCE metamaterials to offer reasonably high actuation stresses/strains at a substantially reduced actuation temperature (46 °C). Such biocompatible LCE metamaterials are integrated with medical dressing to develop a breathable, shrinkable, hemostatic patch as a means of noninvasive treatment. In vivo animal experiments of skin repair with both round and cross-shaped wounds demonstrate advantages of the hemostatic patch over conventional strategies (e.g., medical dressing and suturing) in accelerating skin regeneration, while avoiding scar and keloid generation.

4.
Nature ; 597(7877): 503-510, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34552257

RESUMO

Large, distributed collections of miniaturized, wireless electronic devices1,2 may form the basis of future systems for environmental monitoring3, population surveillance4, disease management5 and other applications that demand coverage over expansive spatial scales. Aerial schemes to distribute the components for such networks are required, and-inspired by wind-dispersed seeds6-we examined passive structures designed for controlled, unpowered flight across natural environments or city settings. Techniques in mechanically guided assembly of three-dimensional (3D) mesostructures7-9 provide access to miniature, 3D fliers optimized for such purposes, in processes that align with the most sophisticated production techniques for electronic, optoelectronic, microfluidic and microelectromechanical technologies. Here we demonstrate a range of 3D macro-, meso- and microscale fliers produced in this manner, including those that incorporate active electronic and colorimetric payloads. Analytical, computational and experimental studies of the aerodynamics of high-performance structures of this type establish a set of fundamental considerations in bio-inspired design, with a focus on 3D fliers that exhibit controlled rotational kinematics and low terminal velocities. An approach that represents these complex 3D structures as discrete numbers of blades captures the essential physics in simple, analytical scaling forms, validated by computational and experimental results. Battery-free, wireless devices and colorimetric sensors for environmental measurements provide simple examples of a wide spectrum of applications of these unusual concepts.

5.
Artigo em Inglês | MEDLINE | ID: mdl-34431114

RESUMO

BACKGROUND: For initial respiratory management, continuous positive airway pressure (CPAP) is increasingly used for preterm infants, especially for gestational age less than 32 weeks. However, neonatologists are concerned about the potential risks of CPAP support failure. OBJECTIVES: To examine the association between different initial respiratory support modalities and the outcomes of preterm infants at <32 weeks of gestation across multiple neonatal intensive care units (NICU) in China. METHODS: This study was carried out over a period of 12 months in 2018. Unadjusted relative risks (RR) for demographic and clinical characteristics were calculated for CPAP failure and CPAP success in the total cohort using log-linear model based on generalised estimating equations for clustered observations. RESULTS: Among 1560 preterm infants delivered at <32 weeks, the incidence of CPAP failure was 10.3%. After adjustment for demographic and clinical factors, the relative risk of mortality (RR 7.54, 95% CI 5.56, 10.44), pneumothorax (RR 9.85, 95% CI 2.89, 61.53), pulmonary haemorrhage (RR 7.78, 95% CI 4.51, 14.64) and BPD (RR 3.65, 95% CI 3.65, 4.51) were considerably higher for infants in the CPAP failure group than those in the CPAP-S group. However, the risk of poor outcomes in CPAP failure infants was similar to that of those in the initial mechanical ventilation (MV) group. CONCLUSIONS: Continuous positive airway pressure failure was associated with an increased risk of mortality and major morbidities, including BPD, pulmonary haemorrhage and pneumothorax, and was comparable to the risk associated with initial MV.

6.
ACS Appl Mater Interfaces ; 13(33): 39915-39924, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34396781

RESUMO

Architected metallic materials generally suffer from a serious engineering problem of mechanical instability manifested as the emergence of localized deformation bands and collapse of strength. They usually cannot exhibit satisfactory shape recoverability due to the little recoverable strain of metallic constituent material. After yielding, the metallic constituent material usually exhibits a continuous low strain-hardening capacity, giving the local yielded regions of architecture low load resistance and easily developing into excessive deformation bands, accompanied by the collapse of strength. Here, a novel constituent material deformation design strategy has been skillfully proposed, where the low load resistance of yielded regions of the architecture can be effectively compensated by the significant self-strengthening behavior of constituent material, thus avoiding the formation of localized deformation bands and collapse of strength. To substantiate this strategy, shape-memory alloys (SMAs) are considered as suitable constituent materials for possessing both self-strengthening behavior and shape-recovery function. A 3D-printing technique was adopted to prepare various NiTi SMA architected materials with different geometric structures. It is demonstrated that all of these architected metallic materials can be stably and uniformly compressed by up to 80% without the formation of localized bands, collapse of strength, and structural failure, exhibiting ultrahigh damage tolerance. Furthermore, these SMA architected materials can display more than 98% shape recovery even after 80% deformation and excellent cycle stability during 15 cycles. This work exploits the amazing impact of constituent materials on constructing supernormal properties of architected materials and will open new avenues for developing high-performance architected metallic materials.

7.
Adv Mater ; 33(37): e2102684, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34342056

RESUMO

Three-dimensional (3D) flexible electronics represent an emerging area of intensive attention in recent years, owing to their broad-ranging applications in wearable electronics, flexible robots, tissue/cell scaffolds, among others. The widely adopted 3D conductive mesostructures in the functional device systems would inevitably undergo repetitive out-of-plane compressions during practical operations, and thus, anti-fatigue design strategies are of great significance to improve the reliability of 3D flexible electronics. Previous studies mainly focused on the fatigue failure behavior of planar ribbon-shaped geometries, while anti-fatigue design strategies and predictive failure criteria addressing 3D ribbon-shaped mesostructures are still lacking. This work demonstrates an anti-fatigue strategy to significantly prolong the fatigue life of 3D ribbon-shaped flexible electronics by switching the metal-dominated failure to desired polymer-dominated failure. Combined in situ measurements and computational studies allow the establishment of a failure criterion capable of accurately predicting fatigue lives under out-of-plane compressions, thereby providing useful guidelines for the design of anti-fatigue mesostructures with diverse 3D geometries. Two mechanically reliable 3D devices, including a resistance-type vibration sensor and a janus sensor capable of decoupled temperature measurements, serve as two demonstrative examples to highlight potential applications in long-term health monitoring and human-like robotic perception, respectively.

8.
BMC Plant Biol ; 21(1): 341, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34281510

RESUMO

BACKGROUND: Restoration through planting is the dominant strategy to conserve mangrove ecosystems. However, many of the plantations fail to survive. Site and seeding selection matters for planting. The process of afforestation, where individuals were planted in a novel environment, is essentially human-controlled transplanting events. Trying to deepen and expand the understanding of the effects of transplanting on plants, we have performed a seven-year-long reciprocal transplant experiment on Kandelia obovata along a latitudinal gradient. RESULTS: Combined phenotypic analyses and next-generation sequencing, we found phenotypic discrepancies among individuals from different populations in the common garden and genetic differentiation among populations. The central population with abundant genetic diversity and high phenotypic plasticity had a wide plantable range. But its biomass was reduced after being transferred to other latitudes. The suppressed expression of lignin biosynthesis genes revealed by RNA-seq was responsible for the biomass reduction. Moreover, using whole-genome bisulfite sequencing, we observed modification of DNA methylation in MADS-box genes that involved in the regulation of flowering time, which might contribute to the adaptation to new environments. CONCLUSIONS: Taking advantage of classical ecological experiments as well as multi-omics analyses, our work observed morphology differences and genetic differentiation among different populations of K. obovata, offering scientific advice for the development of restoration strategy with long-term efficacy, also explored phenotypic, transcript, and epigenetic responses of plants to transplanting events between latitudes.


Assuntos
Rhizophoraceae/crescimento & desenvolvimento , Rhizophoraceae/genética , Biomassa , Conservação dos Recursos Naturais , Metilação de DNA , DNA de Plantas , Ecossistema , Variação Genética , Genética Populacional , Lignanas/biossíntese , Fenótipo , Filogeografia , RNA-Seq
9.
Trends Pharmacol Sci ; 42(8): 657-674, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34270922

RESUMO

Integral membrane proteins (MPs) are important drug targets across most fields of medicine, but historically have posed a major challenge for drug discovery due to difficulties in producing them in functional forms. We review the state of the art in drug discovery strategies using recombinant multipass MPs, and outline methods to successfully express, stabilize, and formulate them for small-molecule and monoclonal antibody therapeutics development. Advances in structure-based drug design and high-throughput screening are allowing access to previously intractable targets such as ion channels and transporters, propelling the field towards the development of highly specific therapies targeting desired conformations.


Assuntos
Descoberta de Drogas , Proteínas de Membrana , Anticorpos Monoclonais , Desenho de Fármacos , Humanos , Canais Iônicos
10.
Cells ; 10(6)2021 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-34199299

RESUMO

The mammalian ovary has two main functions-producing mature oocytes for fertilization and secreting hormones for maintaining the ovarian endocrine functions. Both functions are vital for female reproduction. Primordial follicles are composed of flattened pre-granulosa cells and a primary oocyte, and activation of primordial follicles is the first step in follicular development and is the key factor in determining the reproductive capacity of females. The recent identification of the phosphatidylinositol 3 kinase (PI3K)/phosphatase and tensin homolog deleted on chromosome 10 (PTEN) signaling pathway as the key controller for follicular activation has made the study of primordial follicle activation a hot research topic in the field of reproduction. This review systematically summarizes the roles of the PI3K/PTEN signaling pathway in primordial follicle activation and discusses how the pathway interacts with various other molecular networks to control follicular activation. Studies on the activation of primordial follicles have led to the development of methods for the in vitro activation of primordial follicles as a treatment for infertility in women with premature ovarian insufficiency or poor ovarian response, and these are also discussed along with some practical applications of our current knowledge of follicular activation.


Assuntos
Infertilidade Feminina/metabolismo , Folículo Ovariano/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Insuficiência Ovariana Primária/metabolismo , Transdução de Sinais , Animais , Feminino , Humanos
11.
Environ Sci Pollut Res Int ; 28(35): 49166-49178, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33932211

RESUMO

Passivation of heavy metals is one of the most efficient techniques to remediate soil pollution. However, passivators with single component are usually unsatisfactory in the case of multi-metal contaminated soils. To resolve this problem, a series of combined passivators containing different ratios of Fe-Mn ore, Fe powder, zeolite, bentonite, etc. were designed and used to study their effects on the growth, heavy metal accumulation, and the antioxidant response of Chinese cabbage (Brassica chinensis L.) as well as the soil available forms of heavy metals in a copper refinery's multi-metal (As, Cd, Pb, Cu) contaminated yellow-brown soil and an artificially contaminated (As, Cd, Pb, Cu) calcareous alluvial soil. The results showed that compared with the control, the addition of combined passivators significantly promoted cabbage growth, with the biomass increase up to 1.77 and 3.54 times in yellow-brown soil and calcareous alluvial soil, respectively. The activity of antioxidant enzymes (SOD, CAT, POD) and the content of malondialdehyde (MDA) and glutathione (GSH) decreased, while the chlorophyll content increased significantly, as compared with no passivators. In addition, passivator application decreased As, Cd, Pb, and Cu contents in shoots and roots by 34.8%, 45.6%, 34.9%, and 11.1% and 49.2%, 63.8%, 38.6%, and 46.4% in yellow-brown soil and by 29.8%, 27.3%, 26.8%, and 25.5% and 45.8%, 55.2%, 61.8%, and 5.7% in calcareous alluvial soil, respectively. Besides, the content of soil available heavy metals was reduced by 8.0-17.1% in yellow-brown soil and 3.3-19.1% in calcareous alluvial soil after the application of passivators. The results indicated that the combined passivators formulated in this experiment could efficiently reduce the content of the multi-metals in cabbage and relieve the oxidant stress and could be used as a way to remediate multi-metal polluted soils.


Assuntos
Brassica , Metais Pesados , Poluentes do Solo , Antioxidantes , Poluição Ambiental , Metais Pesados/análise , Solo , Poluentes do Solo/análise
12.
Handb Exp Pharmacol ; 267: 507-545, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33963460

RESUMO

Monoclonal antibodies combine specificity and high affinity binding with excellent pharmacokinetic properties and are rapidly being developed for a wide range of drug targets including clinically important potassium ion channels. Nonetheless, while therapeutic antibodies come with great promise, K+ channels represent particularly difficult targets for biologics development for a variety of reasons that include their dynamic structures and relatively small extracellular loops, their high degree of sequence conservation (leading to immune tolerance), and their generally low-level expression in vivo. The process is made all the more difficult when large numbers of antibody candidates must be screened for a given target, or when lead candidates fail to cross-react with orthologous channels in animal disease models due to their highly selective binding properties. While the number of antibodies targeting potassium channels in preclinical or clinical development is still modest, significant advances in the areas of protein expression and antibody screening are converging to open the field to an avalanche of new drugs. Here, the opportunities and constraints associated with the discovery of antibodies against K+ channels are discussed, with an emphasis on novel technologies that are opening the field to exciting new possibilities for biologics development.


Assuntos
Anticorpos Monoclonais , Canais de Potássio , Animais , Anticorpos Monoclonais/uso terapêutico
13.
Sci Total Environ ; 781: 146756, 2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-33798898

RESUMO

Large hydraulic infrastructures have been constructed globally to address water challenges. Past studies have well documented their effects on downstream aquatic ecosystems, which have included disrupting hydrological regimes as well as nutrient delivery, cycling and mediating processes that affect primary production. However, how these infrastructure operations affect lake ecosystems where the infrastructures are situated remains poorly understood. In the present study, we used a three-dimensional hydrodynamic-biogeochemical lake model to quantify the potential effects of large lake sluice operations under extreme high water levels on current structure and water quality parameters of Lake Chaohu in China. We designed and simulated multiple operation strategies based on actual operation curves during the 2016 extreme rainfall season. The model successfully captured the water quality dynamics of Lake Chaohu during both the calibration and validation phases. Our results indicate that higher lake water release rates led to overall accelerations of the current velocity; however, the deceleration of along-shore current velocity along the shorelines was also evident. Higher release rates also resulted in rapid rises ammonium nitrogen (NH4-N), total nitrogen (TN) and total phosphorous (TP) concentrations in the eastern lake basin, as well as a lake-wide rise of chlorophyll-a (Chla) concentration. When the lake sluice was operated at its full capacity, mean concentrations of these four parameters increased by 5.21%, 5.58%, 9.6% and 7.46%, respectively. Modeling results demonstrate that the effects of lake sluice operations were still quite pronounced for four months after the operations. Modeling results also revealed that higher release rate during the operation phase may help decease TN and TP concentrations during the subsequent period. This study provides a useful perspective on how to support the planning and operation of large infrastructures in the face of climate change induced extreme events.

14.
Artigo em Inglês | MEDLINE | ID: mdl-33809051

RESUMO

Selenium (Se) is an essential and crucial micronutrient for humans and animals, but excessive Se brings negativity and toxicity. The adsorption and oxidation of Se(IV) on Mn-oxide surfaces are important processes for understanding the geochemical fate of Se and developing engineered remediation strategies. In this study, the characterization of simultaneous adsorption, oxidation, and desorption of Se(IV) on δ-MnO2 mineral was carried out using stirred-flow reactors. About 9.5% to 25.3% of Se(IV) was oxidized to Se(VI) in the stirred-flow system in a continuous and slow process, with the kinetic rate constant k of 0.032 h-1, which was significantly higher than the apparent rate constant of 0.0014 h-1 obtained by the quasi-level kinetic fit of the batch method. The oxidation reaction was driven by proton concentration, and its rate also depended on the Se(IV) influent concentration, flow rate, and δ-MnO2 dosage. During the reaction of Se(IV) and δ-MnO2, Mn(II) was produced and adsorbed strongly on Mn oxide surfaces, which was evidenced by the total reflectance Fourier transform infrared (ATR-FTIR) results. The X-ray photoelectron spectroscopy (XPS) data indicated that the reaction of Se(VI) on δ-MnO2 produced Mn(III) as the main product. These results contribute to a deeper understanding of the interface chemical process of Se(IV) with δ-MnO2 in the environment.


Assuntos
Compostos de Manganês , Óxidos , Adsorção , Humanos , Cinética , Oxirredução , Ácido Selenioso
15.
Proc Natl Acad Sci U S A ; 118(11)2021 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-33836614

RESUMO

Structures that significantly and rapidly change their shapes and sizes upon external stimuli have widespread applications in a diversity of areas. The ability to miniaturize these deployable and morphable structures is essential for applications in fields that require high-spatial resolution or minimal invasiveness, such as biomechanics sensing, surgery, and biopsy. Despite intensive studies on the actuation mechanisms and material/structure strategies, it remains challenging to realize deployable and morphable structures in high-performance inorganic materials at small scales (e.g., several millimeters, comparable to the feature size of many biological tissues). The difficulty in integrating actuation materials increases as the size scales down, and many types of actuation forces become too small compared to the structure rigidity at millimeter scales. Here, we present schemes of electromagnetic actuation and design strategies to overcome this challenge, by exploiting the mechanics-guided three-dimensional (3D) assembly to enable integration of current-carrying metallic or magnetic films into millimeter-scale structures that generate controlled Lorentz forces or magnetic forces under an external magnetic field. Tailored designs guided by quantitative modeling and developed scaling laws allow formation of low-rigidity 3D architectures that deform significantly, reversibly, and rapidly by remotely controlled electromagnetic actuation. Reconfigurable mesostructures with multiple stable states can be also achieved, in which distinct 3D configurations are maintained after removal of the magnetic field. Demonstration of a functional device that combines the deep and shallow sensing for simultaneous measurements of thermal conductivities in bilayer films suggests the promising potential of the proposed strategy toward multimodal sensing of biomedical signals.

16.
Sci Adv ; 7(12)2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33731359

RESUMO

Three-dimensional (3D), submillimeter-scale constructs of neural cells, known as cortical spheroids, are of rapidly growing importance in biological research because these systems reproduce complex features of the brain in vitro. Despite their great potential for studies of neurodevelopment and neurological disease modeling, 3D living objects cannot be studied easily using conventional approaches to neuromodulation, sensing, and manipulation. Here, we introduce classes of microfabricated 3D frameworks as compliant, multifunctional neural interfaces to spheroids and to assembloids. Electrical, optical, chemical, and thermal interfaces to cortical spheroids demonstrate some of the capabilities. Complex architectures and high-resolution features highlight the design versatility. Detailed studies of the spreading of coordinated bursting events across the surface of an isolated cortical spheroid and of the cascade of processes associated with formation and regrowth of bridging tissues across a pair of such spheroids represent two of the many opportunities in basic neuroscience research enabled by these platforms.

17.
Appl Environ Microbiol ; 87(11)2021 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-33741614

RESUMO

Coastal wetlands are experiencing frequent flooding because of global climate changes, such as the rising sea level. Despite the key role of archaea in soil biogeochemical cycles, the assembly processes and co-occurrence patterns of archaeal communities in coastal wetlands in response to increasing inundation frequencies remain elusive. In this study, we established an in situ mesocosm with an inundation frequency gradient to investigate the response of soil archaeal community toward increasing inundation frequencies in monocultures of Spartina alterniflora and a mangrove species, Kandelia obovata Both neutral community model and null model analyses suggested that stochastic processes are dominant in governing the archaeal community assembly and that the stochastic processes are enhanced with increasing inundation frequencies. Increasing inundation frequencies significantly increased the community niche width. Moreover, archaeal community in S. alterniflora soil displayed lower niche overlap and higher stochasticity than in K. obovata soil. Co-occurrence network analysis revealed that the network complexity increases with increase in the inundation frequencies. Soil water content is the most decisive factor influencing the archaeal communities. Overall, we found that increasing inundation frequencies enhance the stochastic processes and network complexity of the soil archaeal community in coastal wetlands. This study could enhance our understanding on the response of soil archaeal communities in coastal wetlands toward global change.IMPORTANCE Coastal wetlands, subjected to regular disturbances by periodic tides, are highly productive and important in the regulation of climate change. However, the assembly mechanisms and co-occurrence patterns of soil archaeal communities in coastal areas remain poorly known, especially for their responses to increasing inundation frequencies. In this study, we aimed at unraveling these uncertainties by studying typical estuarine ecosystems in southern China. We show that increasing inundation frequencies enhance the stochastic processes and network complexity of the soil archaeal community. This study offers a new path for an improved understanding of archaeal community assembly and species coexistence in coastal environments, with a special focus on the role of inundation frequency.


Assuntos
Archaea/fisiologia , Inundações , Microbiota , Elevação do Nível do Mar , Microbiologia do Solo , Áreas Alagadas , China , Poaceae/fisiologia , Rhizophoraceae/fisiologia , Processos Estocásticos
18.
Sci Adv ; 7(9)2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33627434

RESUMO

Multistable mechanical metamaterials are artificial materials whose microarchitectures offer more than two different stable configurations. Existing multistable mechanical metamaterials mainly rely on origami/kirigami-inspired designs, snap-through instability, and microstructured soft mechanisms, with mostly bistable fundamental unit cells. Scalable, tristable structural elements that can be built up to form mechanical metamaterials with an extremely large number of programmable stable configurations remains illusive. Here, we harness the elastic tensile/compressive asymmetry of kirigami microstructures to design a class of scalable X-shaped tristable structures. Using these structure as building block elements, hierarchical mechanical metamaterials with one-dimensional (1D) cylindrical geometries, 2D square lattices, and 3D cubic/octahedral lattices are designed and demonstrated, with capabilities of torsional multistability or independent controlled multidirectional multistability. The number of stable states increases exponentially with the cell number of mechanical metamaterials. The versatile multistability and structural diversity allow demonstrative applications in mechanical ternary logic operators and amplitude modulators with unusual functionalities.

19.
Artigo em Inglês | MEDLINE | ID: mdl-33619623

RESUMO

Internal loadings of nutrients play important roles in the eutrophication of shallow lakes. The effective removal of sediments rich in nutrients is of great importance for lake management and the abatement of eutrophication. In this study, grooves were installed in the bottom of Lake Chaohu. Approximately 8.5 months later, the chlorophyll a, organic matter, and total nitrogen contents in the sediment inside the grooves were 1.5-3.0 times, 1.2-1.8 times, and 1.3-1.6 times higher, respectively, than those in the surrounding sediments, and the total phosphorus contents in the bottom grooves were slightly lower than those in the surrounding sediments. The thicknesses of the sediments with high chlorophyll a, organic matter, total nitrogen, and total phosphorus contents in the grooves were 5-15 times greater than those of the surrounding sediments with high pollution contents. Internal pollution was captured in the grooves. The active hydrodynamic process was an important factor related to the effectiveness of this method and is conducive to the transport of polluted sediments to the bottom grooves where they are collected. Bottom grooves have broad application potential for the removal of sediments rich in nutrients from shallow-water lakes; these grooves can be widely used in areas that experience large disturbances from wind waves, have water flows gathering in or entering the lake, or have thin sediments with high pollution contents. This study provides scientific guidance for the control and management of internal pollution in shallow lakes.

20.
Ecology ; 102(5): e03311, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33586146

RESUMO

Patterns of flowering phenology can affect the success of plant invasions, especially when introduced species spread across a wide range of latitude into different climatic conditions. We combined a 4-yr field survey and a 3-yr common garden experiment with the invasive grass Spartina alterniflora that is now widespread along the coast of China to document the latitudinal pattern of flowering phenology, determine if phenology was related to climate or oceanographic variables, and determine whether phenology patterns were fixed versus plastic. In the field, first flowering day displayed a hump-shaped relationship with latitude, with low- and high-latitude plants flowering 100 d and 10 d earlier than plants at middle latitudes, respectively. Peak flowering day showed a similar hump-shaped relationship with latitude, with the interval between first and peak flowering day decreasing with increasing latitude. First flowering day had a hump-shaped relationship with annual growing degree days but a linear positive relationship with tidal range. In the common garden, first flowering day decreased linearly with increasing latitude of origin, as did peak flowering day, and the interval between first and peak flowering day increased with increasing latitude. First flowering day in the common garden had weak or no relationships with abiotic variables at the sites of origin. In both the field and common garden, first flowering day was later in site years for which plants were taller. These results indicate a high degree of plasticity in flowering phenology, with plants flowering later in the field at sites with intermediate temperatures and high tide ranges. Common garden results indicate some selection for earlier flowering at sites with low temperatures, consistent with a shorter growing season. Consistent with life-history theory, plants flowered later under conditions favoring vigorous growth. Earlier flowering and smaller size of plants at high and low latitudes suggests that S. alterniflora has already occupied much of the geographic range favorable for it on the East Coast of Asia.


Assuntos
Espécies Introduzidas , Poaceae , China , Flores , Plantas , Reprodução
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