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Nature has long inspired the design of high-performance structures, offering profound insights into engineering innovations through intricate biological architectures. The rational design of composite curved components is crucial for the lightweight construction of aerospace structures. In the transition from planar constructs to curved components, any mismatch in form can induce high stress, potentially leading to structural compromise or failure. Drawing inspiration from the water lily, a rational design and fabrication approach for cylindrical surface structures is proposed, transitioning from planar to curved surfaces. The adaptation of zero Poisson's ratio honeycomb to cylindrical surface is verified by experiments and simulations. The mismatch relationship between them would lead to the damage failure of the honeycomb. In view of this, the honeycomb sandwich cylinder commonly used in aerospace is fabricated by the proposed method. Theoretical predictions and experimental characterizations were conducted to analyze failure modes under axial compression. This led to the creation of a failure mechanism map for the honeycomb cylinder. Load-mass efficiency analysis revealed that face-crushing failure provides high bearing efficiency. Additionally, the effects of facesheet thickness, along with a comparison of failure modes and imperfection sensitivity between single and sandwich cylinders, were explored. The results indicate that the sandwich cylinder exhibits a higher specific load-bearing capacity and lower imperfection sensitivity compared to the single cylinder. [Display omitted] • Transforming method from planar to cylindrical honeycomb inspired by the Water lily is proposed. • Failure mechanisms of CFRP honeycomb sandwich cylinder are revealed. • Load-bearing efficiency analysis supports honeycomb sandwich cylinder optimization. • The structural strength of the honeycomb sandwich cylinder follows an S-shaped curve as facesheet thickness increases. • Lower imperfection sensitivity of sandwich cylinder compared with single cylinder. [ABSTRACT FROM AUTHOR]

[Display omitted] • Forest SOS begins earliest in the eastern region. • Forest SOS in humid regions still advances during extreme pre-seasonal drought years. • Compared to broadleaf forests, needle-leaved forests exhibit a higher tolerance to drought. • Using the HDA and CDA accumulated temperature models. Global warming is altering ecosystem function and productivity, with changes in vegetation phenology playing a crucial role. These changes are driven not only by rising temperatures but also by the increasing intensity and frequency of extreme events, particularly drought. While the response of the start of the growing season (SOS) to the rising temperature has been widely studied, the mechanisms by which pre-seasonal meteorological drought influence spring phenology in forest ecosystems across different hydroclimatic regions remain poorly understood. We utilized a remote sensing dataset with a spatial resolution of 250 m, integrated with meteorological station data, to examine the response mechanisms of SOS to pre-seasonal drought. This study focuses on four hydroclimatic regions across northern China, providing a comprehensive assessment of regional variations in SOS dynamics. The results revealed that: (1) During the period from 2001 to 2020 forest SOS in humid regions occurs approximately 18 days earlier than in arid regions. SOS in the four hydroclimatic regions showed an average trend of advancement, with an average advancement of 0.31 days per year. (2) The impact of pre-season drought on SOS in forests across four study regions exhibits an intriguing pattern. Short-term pre-season drought significantly influences spring phenology. In humid region, drought causes an advance in the SOS for most areas, whereas in semi-arid region, the forests experience a pronounced delay in SOS due to drought conditions. (3) We further explored the different impact patterns of spring phenology during drought years across various hydroclimatic regions: in humid regions during dry years, SOS is primarily driven by elevated temperatures; conversely, in arid and semi-arid regions, SOS is predominantly influenced by water deficiency resulting from drought conditions. Our findings will enhance the current understanding of ecosystem feedback mechanisms and facilitate the assessment of the capacity of the vegetation to cope with extreme climate change in different regions. [ABSTRACT FROM AUTHOR]

[Display omitted] • An inner core debonding model of CFRP hexagonal honeycomb is established. • Double crack propagation induced core debonding mechanism is revealed. • Theoretical model effectively predicts inner core debonding mechanical response. • Structural parametric analysis provides the distribution area of debonding modes. The inner core debonding of composite sandwich beams with carbon fiber reinforced polymer (CFRP) hexagonal honeycomb core is investigated theoretically and experimentally. Based on the principle of minimum potential energy, a theoretical model is established to reveal the core debonding mechanism with Timoshenko's beam theory and Extended High-Order Sandwich Panel Theory (EHSAPT) for composite face sheets and CFRP hexagonal honeycomb core, respectively. The theoretical approach of core debonding simulation is based on the framework of the cohesive zone model (CZM). By constructing the constitutive relation of the core interface as the discontinuous stress and displacement boundary conditions, the vertical core debonding can be simulated overcoming the singularity of equilibrium equations. The crack propagation process is decomposed into three stages with the consideration of the double crack propagation mechanism. In experiments, the regular and reinforced hexagonal honeycomb sandwich beams are designed and fabricated, and the quantification of the defect degree of the core bonding interface is achieved by equivalent energy release rate obtained from the homogenized hexagonal honeycomb. The double cantilever beam (DCB) experiments are performed to determine the equivalent energy release rate and reveal the core debonding mechanism of CFRP hexagonal honeycomb sandwich beams. Comparing the load–displacement curves and debonding deformation patterns indicates that the established theoretical model can effectively predict the core debonding mechanical response. Finally, parametric analysis is carried out to discuss the impact of structural dimension parameters, defect location and defect degree on the debonding modes of CFRP hexagonal honeycomb sandwich beams. [ABSTRACT FROM AUTHOR]

The protection and utilization of traditional villages have evolved from the individual to the regional level and have gradually formed a network. China has introduced a policy of centralized contiguous protection and utilization areas for traditional villages. Intervention in modern relationships has led to the reconstruction of connections between villages. It is necessary to explore the modern bonds between villages with historical connections. Using the existing 85 centralized contiguous protection and utilization areas and 8155 traditional villages as the research objects, this study depicts the geographical, cultural, and industrial ties of the centralized contiguous protection and utilization areas in 2010 and 2020 based on the information entropy model. In addition, it studies the traditional village network using the gravity model of spatial interaction to explore the evolution and boundary rationality of the centralized contiguous protection and utilization areas. Research has shown that (1) the cultural relationship between centralized contiguous protection and utilization areas has fluctuated over the past decade, and the industrial relationship has generally strengthened. (2) Historical and cultural relics such as architectural relics, intangible heritage sites, and cultural corridors are the main forces that maintain the cultural and industrial ties of villages. Socioeconomic factors generally have a negative impact, and a mechanism exists for the modern bond between centralized contiguous protection and utilization areas to change from cultural connections to industrial connections. (3) Existing centralized contiguous protection and utilization areas have good efficiency. However, there are problems with delineating boundaries in terms of limited county boundaries and large municipal boundaries. Therefore, building a governance framework of a supercluster city and county coordination-centralized contiguous protection and utilization areas is proposed. • Measuring multiple ties of centralized contiguous areas by information entropy. • Historical and cultural relics maintain the kinship and industrial ties of village. • Industrial bonds can easily form separately, but kinship bonds can generate both. • About 40 % of traditional villages include about 70 % of village connections. • A better boundary for contiguous areas should be between city and county levels. [ABSTRACT FROM AUTHOR]

• The accessibility of the high-speed railway (HSR) exhibits a "corridor effect". • The impact of HSR on urban economy and population has a certain time lag effect. • The regional gap between cities was further widened by the HSR. • Large cities benefit from HSR, in contrast to small and medium-sized cities. The high-speed railway (HSR) has been generally regarded as a valid enhancement to national accessibility. However, the debate on the impact of HSR on regions has not reached a consensus. Therefore, we create the accessibility model in nine provinces along the Yellow River based on different years, which incorporates urban scale, travel time, and service frequency of HSR, to dynamically analyze the spatial pattern of urban agglomeration. Moreover, we adapt the Difference-in-differences model to explore the impact on the regional and urban economy and population. The results indicate that HSR significantly improves the accessibility level of most cities in the east and south of nine provinces along the Yellow River, showing a significant "corridor effect." In terms of urban development potential, the spatial distribution pattern of "mass-shaped high-value areas in the east and point-shaped high-value areas in the west" is observed. Furthermore, empirical results show a greater agglomeration rather than diffusion, large cities benefit from HSR with economic promotion, however, HSR causes population loss and economic downturn in small and medium-sized cities. The paper highlights that the HSR does not always bring growth opportunities, a coordinated policy should be implemented for more integrated development of future HSR planning and construction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Face-core interfacial debonding model of all-composite sandwich beam is proposed. • Double cantilever beam tests and theoretical model are validated with each other. • Debonding mechanism of all-composite sandwich beam is revealed. • Load-displacement curve, interfacial strength and damage zone length are predicted. In this paper, the mode I face-core interfacial debonding of an all-composite sandwich beam with carbon fiber reinforced polymer (CFRP) hexagonal honeycomb core is characterized through a theoretical model and double cantilever beam (DCB) tests. The theoretical model is established by combining Timoshenko's beam theory for the face sheets and Extended High Order Sandwich Panel Theory (EHSAPT) for the CFRP hexagonal honeycomb core and the nonlinear exponential cohesive zone model (CZM) is used to model the face-core interfacial constitutive relation, which can couple the normal and the tangential tractions. Then three groups of all-composite sandwich beams with CFRP hexagonal honeycomb core are fabricated and DCB tests are conducted to characterize the mode I face-core interfacial debonding behaviors. The theoretical model is validated by comparing the results of fracture toughness obtained from theoretical calibration and the MBT method. The crack tip relative displacement and crack tip stress indicate the DCB test is mode I and mode II coupled debonding process and it is governed by mode I fracture. Moreover, the mechanism of crack nucleation and propagation between the face-core interface is revealed in detail. Investigation from this paper seeks and to explain the physical phenomenon of the debonding mechanism of all-composite sandwich beams. Finally, a parametric study is carried out to evaluate the effect of fracture toughness, characteristic length, face sheet thickness and fracture factors on the load–displacement response as well as the effect of fracture toughness, characteristic length, face sheet thickness and core thickness on the interfacial strength and damage zone length. [ABSTRACT FROM AUTHOR]

The weakest link in traditional sandwich beams constructed of carbon fiber reinforced polymer (CFRP) honeycomb core is arguably the bonded face sheet-core interface. This has limited the development and the expanded application of these sandwich structures. To overcome this, in this paper, a type of interface-reinforced honeycomb core is proposed to improve the bonding by enlarging the bonding area and thus increasing the strength of the face sheet-to-core attachment. A modified tailor-folding method is employed to fabricate two designs of the interface-reinforced honeycomb. The two interfaces reinforced cores are identical, except for the presence of machined holes in the strengthened fillet created to accommodate adhesive fillets formed during bonding. Double cantilever beam (DCB) test is performed to compare the bonding and behavior of the beams, which are tested alongside beams of a traditional honeycomb that is used as a control sample. In addition, the influences of cell wall thickness and loading direction with respect to the orientation of core macrostructures are also investigated. Modified Beam Theory (MBT) and Elastic Foundation Model (EFM) are employed to calculate the critical strain energy release rate. Overall, the interfaced-reinforced cores performed much better than the traditional core, with the former and latter being stronger in the transverse and longitudinal directions, respectively. The various failure modes observed from the test are analyzed and used to illustrate the strengthening mechanics operating in the interface-reinforced honeycomb. [Display omitted] • Two designs of an interface-reinforced honeycomb are proposed and investigated by the DCB method. • The fabrication process employed to fabricate the honeycomb cores is a modified tailor-folding method. • The influences of cell wall thickness and loading direction are also investigated. • The strain energy release rates G is calculated from the modified beam theory and elastic foundation model. • The debonding characteristics and strengthening mechanics are analyzed by studying the failure modes. [ABSTRACT FROM AUTHOR]

As pivotal regulators unique to plants, NAC family extensively orchestrate various life processes ranging from seed germination through growth and development to responses to environmental stresses. This study unraveled 71 NAC TFs in the carnation (Dianthus caryophyllus L.) genome, designated as DcNAC1 to DcNAC71 , encoding amino acid sequences ranging from 80 to 718 residues. Subcellular localization predictions revealed a predominance of nuclear localization among these DcNACs. Phylogenetic analysis classified DcNACs into 14 distinct subgroups, each exhibiting similar gene structures and motifs. Promoter analysis highlighted the abundance of cis-regulatory elements (CREs) associated with plant growth and development regulation, hormone signaling, light response, and diverse stress responses, with stress-responsive CREs being the most prevalent, with at least one stress-responsive CRE detected in all DcNAC promoters. To assess their functional roles, 12 DcNACs , were randomly selected from different subgroups for expression profiling under heat, ABA, cold, and salt stress conditions, revealing distinct expression patterns for specific stress types. Notably, DcNAC41 , which exhibited marked up-regulation under heat stress, was isolated and subsequently transformed into Arabidopsis. In heat-stressed conditions, transgenic Arabidopsis overexpressing DcNAC41 exhibited significant improvements in growth performance, survival rates, enhanced photosynthetic capacity, and strengthened ROS scavenging abilities. This study offers valuable insights into the comprehensive response of carnation DcNACs towards heat stress, particularly underscoring the potential of DcNAC41 as a promising candidate for enhancing thermotolerance in plants. • 71 DcNAC transcription factors were found in carnation genome. • DcNACs were divided into 14 subgroups with similar gene structures and motifs. • DcNACs promoters contain a variety of stress response elements. • qPCR revealed distinct expression patterns of DcNACs for specific stress types. • DcNAC41 was a promising candidate gene for enhancing thermotolerance in plants. [ABSTRACT FROM AUTHOR]

Polyacrylamide hydrogels are widely used in medicine, petrochemical, water treatment and other fields, among which polyacrylamide hydrogels play an important role in oilfield Profile control and water shutoff and enhanced oil recovery, however, there are few reports on the effect of different inorganic salt solutions on the properties of SiO 2 composite hydrogel. In this paper, a cross-linked SiO 2 composite hydrogel was constructed using Materials Studio software for the first time, and its structure and properties in inorganic salt aqueous solutions were studied. The results show that the addition of inorganic salts can weaken the interaction between water molecules and hydrogels, and this effect is minimal in calcium chloride solution. The radial distribution function shows that there are strong hydrogen bonds between nitrogen and oxygen atoms in the amide group and water molecules, but there are van der Waals forces between oxygen and water atoms, and the addition of inorganic salts will enhance the hydration of nitrogen atoms in the amide group and the interaction between monovalent ions and amide groups was greater than that between bivalent ions. At the same time, the addition of inorganic salts can also enhance the diffusion ability of water molecules and the fluidity of polymer chains. Among the four inorganic salt solutions, Calcium chloride solution has the least effect on the polymer chain and the cross-linked SiO 2 composite hydrogel has the best expansion performance in calcium chloride solution, which is basically consistent with the experimental results, this has a potential application prospect in the reservoir with high calcium content for profile control and water plugging and enhanced oil recovery. [Display omitted] • Cross-linked SiO 2 composite hydrogel in inorganic salt solution is established. • Effects of different inorganic salt solutions on the interaction energy of composites each component are studied. • Both nitrogen and oxygen atoms in amide groups have strong hydrogen bonds with water molecules. • Main controlling factors affecting the fluidity of cation and polymer chains are revealed. • SiO 2 composite hydrogel has the best expansion performance in calcium chloride solution. [ABSTRACT FROM AUTHOR]

Cone-shaped sandwich structures are extensively employed in various fields due to their excellent bearing efficiency and designability. In this work, the design approach and integrated manufacturing method for the carbon fiber reinforced plastic (CFRP) corrugated sandwich truncated cone (CSTC) are proposed to improve the anti-debonding ability and ensure the reliability of the sandwich cone. First, the theoretical model for the stiffness of the CSTC is derived, in which the conservative prediction and the upper limit considering the fiber orientation of the cone are derived. The multiple failure modes of the CSTC under axial compression are theoretically established. Then, the failure mechanism map of the CSTC is established to forecast the possible failure modes. The typical failure modes of local buckling, face fracture, and core buckling are captured by experiments and finite element analysis (FEA). The theoretical model of the stiffness and failure modes is verified by the experiments and FEA. The effect of the semi-vertex angle and circumferential cell number on the failure modes is revealed. Furthermore, a more comprehensive failure mechanism map is generated by altering the geometric parameters of the CSTC. The failure modes of Euler buckling and global buckling are acquired by the comprehensive failure mechanism map and verified by FEA. Finally, the optimum design of the CSTC structure is performed. The results show that the failure mode of face fracture has the best bearing efficiency. This research provides a solid foundation for designing and applying lightweight CSTCs in constructions, such as the adapter of launch vehicles. [Display omitted] • The structure design method and integrated preparation technology of CFRP corrugated sandwich truncated cone are proposed. • The theoretical models of the stiffness and failure modes of the CSTC under axial compression are derived and verified. • The conical sandwich structure is more prone to global buckling with the increase of the semi-vertex angle. • It is found that the failure mode of face crushing has the highest bearing efficiency in structural optimal design. [ABSTRACT FROM AUTHOR]

Carnation (Dianthus caryophyllus L.) is a floral crop that is highly valuable commercially. However, high temperatures adversely affect its growth and the quality of its cut flowers. Melatonin (MT) is a indole substance that can mitigate plant damage under heat stress. In this study, the leaves of carnation seedlings were sprayed with different concentrations of MT before exposure to high temperature. The indices of growth, physiological and chlorophyll fluorescence were measured and analyzed by the membership function method. The results showed that treatment with 100 μM MT was the most effective at ameliorating damage on carnation. We then analyzed the effects of 100 μM MT pretreatment on carnation at different time points of heat stress and found that this concentration of MT ameliorated the damage caused by heat stress, increased the content of photosynthetic pigments, enhanced the performance of photosystem II and improved photosynthesis. In addition, MT also reduced cell damage and lipid peroxidation, increased the activities of antioxidant enzymes and regulated the accumulation of osmotic substances in carnation. Moreover, MT increased the fresh/dry weight of stems and roots, promoted the opening of stomata, and protected the integrity of chloroplast structure of carnation. Compared with heat stress, pre-spraying with MT significantly down-regulated the transcription of a chlorophyll degradation gene and up-regulated the transcription of stress-related genes. Overall, this study provides a theoretical foundation for the mitigation of the adverse effects of exogenous MT under heat stress and proposes beneficial implications for the management of other plants subjected to global warming. • Possible mechanism of exogenous melatonin alleviating high temperature of carnation. • Melatonin improved the biomass, oxidative damage and osmotic accumulation. • Melatonin enhanced the performance of photosystem II at high temperature. • Melatonin promoted stomatal opening and reduced chloroplast damage. • Melatonin up-regulated the expression of genes related to heat tolerance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon fiber composite curved-wall honeycomb was designed to reduce in-plane stiffness. • A modified co-curing method was selected for fabrication process. • The theoretical model and three-dimensional failure mechanism map of carbon fiber composite curved-wall honeycomb is established. • The bending flexibility improved by nearly ten times and is comparable to that of aluminum honeycomb. • The peak bending load per unit mass improved 51.64% after replacing straight wall with semicircular curved wall. Designing curved surfaces with a traditional straight-walled honeycomb is challenging due to its excessive in-plane stiffness, making it prone to fracturing during bending. The research motivation is overcoming the flexibility limitation of conventional straight-wall honeycombs with the new curved-wall design. Moreover, the three-dimensional failure mechanism map based on the theoretical models is expected to contribute to the design of a carbon fiber composite curved-wall honeycomb. This paper outlines the fabrication process using a modified co-curing method. It also includes theoretical models developed to examine the effect of the center angle of curved walls on the honeycomb's in-plane stiffness and bending behavior. In-plane tensile and three-point bending tests were conducted to verify the theoretical modes. Finite element model was created to study the stress distribution and damage degree. The study is also aimed at examining the load-bearing capacity of sandwich beams with curved-wall honeycomb cores. A three-dimensional failure mechanism map shows how the failure modes of sandwich structures are affected by the center angle of the curved walls. The study offers a new approach to designing carbon fiber composite honeycombs with flexible bending deformation and high load-bearing capacity. These honeycombs could potentially be used in lightweight launch-vehicle shell structures. [ABSTRACT FROM AUTHOR]

• Different damage states of CFRP honeycomb sandwich structure are revealed through low-velocity impact experiments. • A refined finite element model suitable for plain weave CFRP composite is established to accurately predict the impact response of the structure. • The energy absorption mechanism of CFRP honeycomb sandwich structure is investigated. • The impact-induced damage is characterized by industrial tomography technology (CT) without destroying the sandwich structure. • Reducing the cell side length is a better way to improve the impact resistance of CFRP honeycomb sandwich structure. The objective of this study is to examine the response and failure of honeycomb sandwich structures made of carbon fiber reinforced polymer (CFRP) composites under low-velocity impacts. Four impact tests with varying energies are performed to induce four distinct damage states in the sandwich structure: no discernible damage, damage to the top face sheet and a portion of the core, damage to the lower face sheet, and total penetration. The damage characteristics of the sandwich structures is analyzed by using industrial tomography technology (CT) without destroying them. A refined finite element model is established to further explain the deformation behavior and energy absorption mechanism of the structure, clarifying the effects of the honeycomb core's structural parameters, such as wall thickness, cell side length, and core height. To enhance the precision of simulation outcomes, a model for the onset and progression of damage in plain woven composites is incorporated into the user-defined material subroutine. The experiments and simulations demonstrate a high level of consistency in terms of peak loads, failure mode, and energy absorption. [Display omitted] [ABSTRACT FROM AUTHOR]

The modern adaptability of traditional villages has received considerable attention worldwide. The composition of different local elements leads to a differentiation between native and constructed localities in the modern adaptation of rural areas. By introducing a circular perspective based on field-spatial production theory, this study takes Qucun Village in Sanmenxia and Mingyue Village in Chengdu, China, as case sites and finds that the local system has full potential to serve as the keynote of rural development and that foreign resources are embedded in the local area to achieve two-way support with local elements. Through research, it can be found that economic capital supports the existence of locality in modern times, cultural capital clarifies the level of native and constructed characteristics, social capital expands the connotation of "locality", and symbolic capital shapes the value of native and constructed localities. Subsequently, the paper reveals that native and constructed localities are not opposites, but shape new spatial hotspots and enrich the network levels of localities, thus enabling the countryside to adapt to dynamic evolution. • Localities of the two villages were compared based on multiple subjects. • Constructing field-spatial circular production theory to explain locality changes. • Constructed locality sometimes strengthens the native locality of the village. • Locality promotes rural adaptation to modernity by integrating complex resources. [ABSTRACT FROM AUTHOR]

The winding-based method is used for fabricating all carbon fiber reinforced plastic (CFRP) cylindrical honeycomb sandwich shell. The theoretical model of multi-failure modes of the cylindrical honeycomb sandwich shell is established under three-point bending. The multiple failure mechanisms of the honeycomb sandwich shell under three-point bending are revealed by the established three-dimensional failure mechanism map. The theoretical prediction of multi-failure modes is verified by experiments and finite element method. The acoustic emission (AE) technology is implemented to detect the evolution rule of internal damage of honeycomb sandwich shell. The damage patterns of the acoustic emission signals with different failure modes are identified by the unsupervised k-means clustering algorithm. The meso-damage mechanisms are also disclosed by the digital microscope. It was found that high peak frequency of the AE signals represents the face-core debonding failure. Finally, the optimal geometric design of the honeycomb sandwich shell under the bending load was carried out. The damage characteristics from mesoscale damage to macroscale failure provide a crucial foundation for discriminating multiple damage failure modes of structures. [Display omitted] • All-CFRP cylindrical honeycomb sandwich shell was fabricated by the developed winding-based method. • The theoretical prediction of the failure modes was established under three-point bending and verified by FEA and the experiments. • The unsupervised k-means clustering algorithm was conducted to identify the damage patterns. • It is found that the high peak frequency of the AE signals corresponds to face-core debonding. [ABSTRACT FROM AUTHOR]