Preserving genetic diversity is crucial for the long-term survival of wild plant species,yet many remain at risk of genetic erosion due to small population sizes and habitat fragmentation.Here,we present a comparative...Preserving genetic diversity is crucial for the long-term survival of wild plant species,yet many remain at risk of genetic erosion due to small population sizes and habitat fragmentation.Here,we present a comparative genomic study of the critically endangered Oreocharis esquirolii(Gesneriaceae)and its widespread congener O.maximowiczii.We assembled and annotated chromosome-level reference genomes for both species and generated whole-genome resequencing data from 28 O.esquirolii and 79 O.maximowiczii individuals.Our analyses reveal substantially lower genetic diversity and higher inbreeding in O.esquirolii,despite its overall reduced mutational burden.Notably,O.esquirolii exhibits an elevated proportion of strongly deleterious mutations relative to O.maximowiczii,suggesting that limited opportunities for purging have allowed these variants to accumulate.These contrasting genomic profileslikely reflectdivergent demographic histories,with O.esquirolii having experienced severe bottlenecks and protracted population decline.Collectively,our findingshighlight the critically endangered status of O.esquirolii,characterized by diminished genetic diversity,pronounced inbreeding,and reduced ability to eliminate deleterious alleles.This study provides valuable genomic resources for the Gesneriaceae family and underscores the urgent need for targeted conservation measures,including habitat protection and ex situ preservation efforts,to mitigate the extinction risk facing O.esquirolii and potentially other threatened congeners.展开更多
Ceramic cores are key to forming a cooling structure within the hollow blade cavities.The use of stereolithography(SL)3D printing technology eliminates the need for moulds,facilitating the preparation of complex-shape...Ceramic cores are key to forming a cooling structure within the hollow blade cavities.The use of stereolithography(SL)3D printing technology eliminates the need for moulds,facilitating the preparation of complex-shaped ceramic cores.In this study,silica-based ceramic cores incorporating nano-3YSZ(3mol.% yttria stabilised zirconia)and micron-sized Y_(2)O_(3) were prepared via SL 3D printing ceramic technology to promote the formation of cristobalite and ZrSiO_(4),thereby improving the high-temperature properties.The flexural strength at 25℃ and 1,500℃,deflection at 1,500℃,shrinkage rate,and porosity of the core samples sintered at different temperatures(1,170℃,1,185℃,1,200℃,1,215℃,and 1,230℃)were tested and investigated.The mechanism underlying the high temperature performance of the cores was elucidated through analysis of cross-sectional morphology,element distribution,and phase constitution of the samples.As the sintering temperature increases,the shrinkage and flexural strength at 25℃ of the core rise,while the open porosity and deflection at 1,500℃ decrease.When the sintering temperature reaches 1,200℃ or higher,the 1,500℃ flexural strength can be measured,which increases as the sintering temperature rises.The core exhibits excellent creep resistance when sintered at temperatures of 1,200℃ and above.Considering the comprehensive performance requirements for the core,the sintering temperature of 1,200℃ was selected.At the sintering temperature of 1,200℃,the core exhibits shrinkage rates of 3.76%(X),3.38%(Y),and 3.95%(Z),alongside a flexural strength of 9.01 MPa at 25℃ and 32.15 MPa at 1,500℃,and an open porosity of 26.39%.The deflection of the core at 1,500℃ is 0.15 mm,which helps to maintain the dimensional stability of the ceramic core during casting.XRD results indicate that samples fractured after 25℃ flexural strength test still contain amorphous quartz glass,alongside substantial quantities of yttria stabilized zirconia and Y_(2)O_(3).Samples fractured after 1,500℃ flexural strength test exhibit significant crystallisation of amorphous quartz glass into cristobalite,with silica and 3YSZ combining to form ZrSiO_(4).Y_(2)O_(3) as a network modifier of the glass network destroys the bridging oxygen in the silica-oxygen bond,thereby reducing the energy required for glass crystallisation and promoting the crystallisation reaction of quartz glass to form cristobalite.In addition,nano-3YSZ combines with SiO_(2) at high temperatures to form ZrSiO_(4).Since cristobalite and ZrSiO_(4) are crystals,both of them have strong creep resistance,thus improving the high temperature flexural strength and deformation resistance of the ceramic cores.展开更多
物种是生物多样性的基本单元,生殖隔离被认为是物种形成的关键;然而物种并不是静止的而是处于不断的分化演变之中,已经稳定成型但尚未到达分化后期的物种可能存在不完全的生殖隔离。对于物种的认识不能单从某一侧面或局部特征来界定,而...物种是生物多样性的基本单元,生殖隔离被认为是物种形成的关键;然而物种并不是静止的而是处于不断的分化演变之中,已经稳定成型但尚未到达分化后期的物种可能存在不完全的生殖隔离。对于物种的认识不能单从某一侧面或局部特征来界定,而应通过"整合物种概念"来确定物种地位。Flora of China记载了中国产白桫椤属(Sphaeropteris)2种,即白桫椤(S.brunoniana)和笔筒树(S.lepifera),并认为原产中国海南的海南白桫椤(S.hainanensis)和白桫椤为同一物种而将其并入白桫椤;但海南白桫椤在形态上已出现了分化。为探讨白桫椤及其近缘物种的亲缘关系和物种多样性分化的情况,本文采集到9个居群共21个样本,通过GBS简化基因组测序技术获得单核苷酸变异位点(SNP),进行系统发育树的构建和主成分及遗传结构的分析,并结合叶片数量性状的统计分析和孢子形态的观察测量。结果表明,海南白桫椤不仅与云南产白桫椤的基因型不同,且在叶片特征和孢子纹饰上有明显差异;但两个居群的生殖隔离较弱,在广西沿海地区形成杂交产物,其叶片特征为亲本的中间类型。因此,我们认为海南白桫椤是由于地理隔离而形成的一个处在分化路上的物种,建议恢复其物种地位;广西产白桫椤为自然杂交群体,应另处理为独立的自然杂交分类群--广西白桫椤(S. brunoniana×hainanensis)。展开更多
AIM: To investigate the roles of nuclear factor(NF)-κB and angiotensin Ⅱ receptor type 1(AT1R) in the pathogenesis of non-alcoholic fatty liver disease(NAFLD).METHODS: Forty-two healthy adult male SpragueDawley rats...AIM: To investigate the roles of nuclear factor(NF)-κB and angiotensin Ⅱ receptor type 1(AT1R) in the pathogenesis of non-alcoholic fatty liver disease(NAFLD).METHODS: Forty-two healthy adult male SpragueDawley rats were randomly divided into three groups:the control group(normal diet), the model group,and the intervention group(10 wk of a high-fat diet feeding, followed by an intraperitoneal injection of PDTC); 6 rats in each group were sacrificed at 6, 10,and 14 wk. After sacrifice, liver tissue was taken,paraffin sections of liver tissue specimens were prepared, hematoxylin and eosin(HE) staining was performed, and pathological changes in liver tissue(i.e., liver fibrosis) were observed by light microscopy.NF-κB expression in liver tissue was detected by immunohistochemistry, and the expression of AT1 R in the liver tissue was detected by reverse transcriptionpolymerase chain reaction(RT-PCR). The data are expressed as mean ± SD. A two-sample t test was used to compare the control group and the model group at different time points, paired t tests were used to compare the differences between the intervention group and the model group, and analysis of variance was used to compare the model group with the control group. Homogeneity of variance was analyzed with single factor analysis of variance. H variance analysis was used to compare the variance. P < 0.05 wasconsidered statistically significant.RESULTS: The NAFLD model was successful after 6wk and 10 wk. Liver fibrosis was found in four rats in the model group, but in only one rat in the intervention group at 14 wk. Liver steatosis, inflammation, and fibrosis were gradually increased throughout the model. In the intervention group, the body mass,rat liver index, serum lipid, and transaminase levels were not increased compared to the model group.In the model group, the degree of liver steatosis was increased at 6, 10, and 14 wk, and was significantly higher than in the control group(P < 0.01). In the model group, different degrees of liver cell necrosis were visible and small leaves, punctated inflammation,focal necrosis, and obvious ballooning degeneration were observed. Partial necrosis and confluent necrosis were observed. In the model group, liver inflammatory activity scores at 6, 10, and 14 wk were higher than in the control group(P < 0.01). Active inflammation in liver tissue in the intervention group was lower than in the model group(P < 0.05). HE staining showed liver fibrosis only at 14 wk in 4/6 rats in the model group and in 1/6 rats in the intervention group. NF-κB positive cells were stained yellow or ensemble yellow,and NF-κB was localized in the cytoplasm and/or nucleus. The model group showed NF-κB activation at6, 10, and 14 wk in liver cells; at the same time points,there were statistically significant differences in the control group(P < 0.01). Over time, NF-κB expression increased; this was statistically lower(P < 0.05) at14 weeks in the intervention group compared to the model group, but significantly increased(P < 0.05)compared with the control group; RT-PCR showed that AT1 R mRNA expression increased gradually in the model group; at 14 wk, the expression was significantly different compared with expression at 10 weeks as well as at 6 weeks(P < 0.05). In the model group, AT1 R mRNA expression was significantly higher than at the same time point in the control group(P <0.01).CONCLUSION: With increasing severity of NAFLD,NF-κB activity is enhanced, and the inhibition of NF-κB activity may reduce AT1 R mRNA expression in NAFLD.展开更多
The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica.Nevertheless,the filler network str...The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica.Nevertheless,the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques.Herein,small-angle neutron scattering(SANS)and synchrotron radiation X-ray nano-computed tomography(Nano-CT)techniques are employed to explore the evolution of filler networks of fumed,precipitated and sol-gel silica,respectively.Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates.And the silica with highly associated structure,pertaining to amorphous morphology,small size,and large surface area,presents short distance and effective molecular chain bridge between aggregates,thus forming strong and steady filler networks.This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.展开更多
Understanding genome-wide diversity,inbreeding,and the burden of accumulated deleterious mutations in small and isolated populations is essential for predicting and enhancing population persistence and resilience.Howe...Understanding genome-wide diversity,inbreeding,and the burden of accumulated deleterious mutations in small and isolated populations is essential for predicting and enhancing population persistence and resilience.However,these effects are rarely studied in limestone karst plants.Here,we re-sequenced the nuclear genomes of 62 individuals of the Begonia masoniana complex(B.liuyanii,B.longgangensis,B.masoniana and B.variegata)and investigated genomic divergence and genetic load for these four species.Our analyses revealed four distinct clusters corresponding to each species within the complex.Notably,there was only limited admixture between B.liuyanii and B.longgangensis occurring in overlapping geographic regions.All species experienced historical bottlenecks during the Pleistocene,which were likely caused by glacial climate fluctuations.We detected an asymmetric historical gene flow between group pairs within this timeframe,highlighting a distinctive pattern of interspecific divergence attributable to karst geographic isolation.We found that isolated populations of B.masoniana have limited gene flow,the smallest recent population size,the highest inbreeding coefficients,and the greatest accumulation of recessive deleterious mutations.These findings underscore the urgency to prioritize conservation efforts for these isolated population.This study is among the first to disentangle the genetic differentiation and specific demographic history of karst Begonia plants at the whole-genome level,shedding light on the potential risks associated with the accumulation of deleterious mutations over generations of inbreeding.Moreover,our findings may facilitate conservation planning by providing critical baseline genetic data and a better understanding of the historical events that have shaped current population structure of rare and endangered karst plants.展开更多
To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn an...To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn and Al contents in the steel and the reaction time on the interfacial reaction were investigated.It was observed that the erosion of the MgO refractory is caused by the reaction of Al and Mn in the steel with MgO in the refractory,which would lead to the formation of(Mn,Mg)O·Al_(2)O_(3) spinel and(Mn,Mg)O solid solution.The formation mechanism of the spinel and solid solution is as follows.The Al in the steel firstly reacts with MgO in the refractory to generate MgO·Al_(2)O_(3) spinel,and then,the spinel reacts with Mn in the steel to form(Mn,Mg)O·Al_(2)O_(3) spinel.Finally,the MnO in the spinel reacts with the MgO in the inner refractory to form(Mn,Mg)O solid solution.In addition,only(Mn,Mg)O·Al_(2)O_(3) spinel is present in the interfacial reaction layer of the refractory when the Al content in the steel is sufficient.展开更多
By using a simplified Coulomb explosion model, the laser-driven Coulomb explosion processes of three deuterated alkane clusters, i.e., deuterated methane（CD4）N, ethane（C2D6）N and propane（C3D8）N clusters are simu...By using a simplified Coulomb explosion model, the laser-driven Coulomb explosion processes of three deuterated alkane clusters, i.e., deuterated methane（CD4）N, ethane（C2D6）N and propane（C3D8）N clusters are simulated numerically.The overrun phenomenon that the deuterons overtake the carbon ions inside the expanding clusters, as well as the dependence of the energetic deuterons and fusion neutron yield on cluster size, is discussed in detail. Researches show that the average kinetic energy of deuterons and neutron yield generated in the Coulomb explosion of（C2D6）N cluster are higher than those of（CD4）N cluster with the same size, in qualitative agreement with the reported conclusions from the experiments of（C2 H6）N and（CH4）N clusters. It is indicated that（C2D6）N clusters are superior to（CD4）N clusters as a target for the laser-induced nuclear fusion reaction to achieve a higher neutron yield. In addition, by comparing the relevant data of（C3D8）N cluster with those of（C2D6）N cluster with the same size, it is theoretically concluded that（C3D8）N clusters with a larger competitive parameter might be a potential candidate for improving neutron generation. This will provide a theoretical basis for target selection in developing experimental schemes on laser-driven nuclear fusion in the future.展开更多
Both biotic and abiotic factors are expected to drive species diversification,yet demonstrating their synergistic effects within a single framework is challenging and has rarely been studied.The recent and rapid radia...Both biotic and abiotic factors are expected to drive species diversification,yet demonstrating their synergistic effects within a single framework is challenging and has rarely been studied.The recent and rapid radiation of the genus Aspidistra(cast-iron plant)provides an ideal system for examining these processes.Here,we generated restriction site-associated DNA sequencing data for 123 Aspidistra taxa and reconstructed wellresolved phylogenies using both concatenationand coalescent-based approaches.Using a comprehensive suite of diversification models,we quantified the contributions of multiple biotic and abiotic factors and applied phylogenetic path analysis to detect their synergistic effects.Our phylogenetic analyses recovered two main clades that differ in stem habits.We found that the diversification of Aspidistra has been driven by both abiotic factors(paleotemperature and the East Asian monsoon)and biotic factors(interspecific competition and pollination mutualism).Notably,these drivers operated both independently and synergistically to facilitate the rapid radiation of Aspidistra.Beyond providing a robust phylogeny useful for classifying Aspidistra,we present a statistical framework for better understanding the macroevolutionary processes underlying rapid plant radiations.Our findings underscore the critical importance of integrating multiple biotic and abiotic drivers into a unified analytical framework to comprehensively understand diversification history.展开更多
Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in v...Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in various photonic systems,and it guides the behavior of these singularities,including the generation and annihilation of BICs.This work theoretically reveals the simultaneous generation of two distinct polarization singularity types,which include off-Γaccidental BICs and Dirac-type band degeneracy points.The generation is driven by a quadratic degeneracy of symmetry-protected BICs in a photonic crystal slab.It should be noted that this is achieved through continuously tuning a geometric parameter without breaking symmetry.Importantly,the generation of both singularity types can be explained by the topological charge conservation law.This adherence ensures the stability of these singularities and allows for continuous tuning of their positions in momentum space by continuously tuning a geometric parameter while preserving symmetry.This study presents a novel framework for synthesizing and manipulating complex polarization states by combining polarization singularities from both BICs and band degeneracies and holds promise for application in other wave systems beyond photonics.展开更多
Due to high penetration,low photo-toxicity,and low background signal of red-shifted visible light,the development of visible-light photochromic materials is of great importance but still a challenging task.In this stu...Due to high penetration,low photo-toxicity,and low background signal of red-shifted visible light,the development of visible-light photochromic materials is of great importance but still a challenging task.In this study,four one-dimensional(1D)naphthalenediimide(NDI)photochromic coordination polymers(CPs),namely{[ZnCl_(2)(4-PMNDI)]·H_(2)O}_(n)(1),{[ZnBr_(2)(4-PMNDI)]·2H_(2)O}_(n)(2),{[ZnCl_(2)(3-PMNDI)]}_(n)(3)and{[ZnBr_(2)(3-PMNDI)]}_(n)(4)(4-/3-PMNDI=N,N’-bis(4-/3-pyridylmethyl)-1,4,5,8-naphthalenediimide),have been designed and synthesized by the combination of positional isomeric electron-deficient PMNDI(electron acceptors,EAs)and electron-rich zinc halides(electron donors,EDs)under solvothermal conditions.The distinct photochromic properties of 1-4 should be attributed to the formation of different interfacial contacts of EDs/EAs due to the introduction of 4-/3-PMNDI positional isomers and different halogen anions.Noteworthily,the much more rapid photoresponsive rates of visible-light photochromism for 1-4 with respect to those of UV-light photochromism exposits that the electronic absorption band of charge transfer(CT)interactions in the visible light region can effectively trigger electron transfer(ET)promptly.Furthermore,1 exhibits a high photosensitivity property in response to wavelengths of 390-450 nm,and it can be applied in detection/filtration of harmful blue rays.This work breaks through an orthodox concept that the ET reaction can only be activated by the electronic absorption band of EDs or EAs(usually in the UV light region),and provides a simple and feasible method for the construction of visible-light photochromic materials.展开更多
Spontaneous hybridization in ex situ facilities can undermine the genetic integrity of ex situ collections and potentially contaminate open-pollinated seeds or seedlings destined for the reintroduction of endangered p...Spontaneous hybridization in ex situ facilities can undermine the genetic integrity of ex situ collections and potentially contaminate open-pollinated seeds or seedlings destined for the reintroduction of endangered plant species into the wild. In the present study, the potential risk of hybridization between two endangered Chinese endemic species, namely Sinojackia xylocarpa Hu and S. rehderiana Hu, which are naturally allopatric species but were conserved ex situ in Wuhan Botanical Garden （WBG）, Wuhan, China, were investigated over three consecutive years from 2003 to 2005. The entire overlapping flowering period of the two species was 14-20 d and the two species shared the same pollinator insects during the entire flowering season in WBG. The floral isolation between the two species was not an issue in the ex sltu collection at WBG. The results suggest an opportunity for pollen transfer between species and a potential risk of genetic Introgression and loss of genetic identity of open-pollinated seeds produced in the ex sltu Collection of these two endangered species. An artificial reciprocal cross between S xylocarpa and S. rehderlana confirmed that the two congener species could readily set seeds, indicating no post-pollination barriers to hybridization and the importance of spatial isolation as a barrier to inter-specific crossing. Therefore, to manage these crossable species with overlapping flowering times and shared pollination vectors in ex situ facilities, spatial isolation should be carefully considered to minimize the possibility of spontaneous hybridization.展开更多
Metasurfaces have enabled the realization of several optical functionalities over an ultrathin platform,fostering the exciting field of flat optics.Traditional metasurfaces are achieved by arranging a layout of static...Metasurfaces have enabled the realization of several optical functionalities over an ultrathin platform,fostering the exciting field of flat optics.Traditional metasurfaces are achieved by arranging a layout of static meta-atoms to imprint a desired operation on the impinging wavefront,but their functionality cannot be altered.Reconfigurability and programmability of metasurfaces are the next important step to broaden their impact,adding customized on-demand functionality in which each meta-atom can be individually reprogrammed.We demonstrate a mechanical metasurface platform with controllable rotation at the meta-atom level,which can implement continuous Pancharatnam–Berry phase control of circularly polarized microwaves.As the proof-of-concept experiments,we demonstrate metalensing,focused vortex beam generation,and holographic imaging in the same metasurface template,exhibiting versatility and superior performance.Such dynamic control of electromagnetic waves using a single,low-cost metasurface paves an avenue towards practical applications,driving the field of reprogrammable intelligent metasurfaces for a variety of applications.展开更多
We show that inhomogeneous waveguides of slowly varied parity-time(PT) symmetry support localized optical resonances.The resonance is closely related to the formation of exceptional points separating exact and broken ...We show that inhomogeneous waveguides of slowly varied parity-time(PT) symmetry support localized optical resonances.The resonance is closely related to the formation of exceptional points separating exact and broken PT phases.Salient features of this kind of non-Hermitian resonance, including the formation of half-vortex flux and the discrete nature,are discussed.This investigation highlights the unprecedented uniqueness of field dynamics in non-Hermitian systems with many potential adaptive applications.展开更多
基金supported by National Key R&D Program of China(2024YFF1307400)Guangdong S&T Program(2022B1111230001).
文摘Preserving genetic diversity is crucial for the long-term survival of wild plant species,yet many remain at risk of genetic erosion due to small population sizes and habitat fragmentation.Here,we present a comparative genomic study of the critically endangered Oreocharis esquirolii(Gesneriaceae)and its widespread congener O.maximowiczii.We assembled and annotated chromosome-level reference genomes for both species and generated whole-genome resequencing data from 28 O.esquirolii and 79 O.maximowiczii individuals.Our analyses reveal substantially lower genetic diversity and higher inbreeding in O.esquirolii,despite its overall reduced mutational burden.Notably,O.esquirolii exhibits an elevated proportion of strongly deleterious mutations relative to O.maximowiczii,suggesting that limited opportunities for purging have allowed these variants to accumulate.These contrasting genomic profileslikely reflectdivergent demographic histories,with O.esquirolii having experienced severe bottlenecks and protracted population decline.Collectively,our findingshighlight the critically endangered status of O.esquirolii,characterized by diminished genetic diversity,pronounced inbreeding,and reduced ability to eliminate deleterious alleles.This study provides valuable genomic resources for the Gesneriaceae family and underscores the urgent need for targeted conservation measures,including habitat protection and ex situ preservation efforts,to mitigate the extinction risk facing O.esquirolii and potentially other threatened congeners.
基金financially supported by the Liaoning Province Science and Technology Plan Joint Program(2023JH2/101700037).
文摘Ceramic cores are key to forming a cooling structure within the hollow blade cavities.The use of stereolithography(SL)3D printing technology eliminates the need for moulds,facilitating the preparation of complex-shaped ceramic cores.In this study,silica-based ceramic cores incorporating nano-3YSZ(3mol.% yttria stabilised zirconia)and micron-sized Y_(2)O_(3) were prepared via SL 3D printing ceramic technology to promote the formation of cristobalite and ZrSiO_(4),thereby improving the high-temperature properties.The flexural strength at 25℃ and 1,500℃,deflection at 1,500℃,shrinkage rate,and porosity of the core samples sintered at different temperatures(1,170℃,1,185℃,1,200℃,1,215℃,and 1,230℃)were tested and investigated.The mechanism underlying the high temperature performance of the cores was elucidated through analysis of cross-sectional morphology,element distribution,and phase constitution of the samples.As the sintering temperature increases,the shrinkage and flexural strength at 25℃ of the core rise,while the open porosity and deflection at 1,500℃ decrease.When the sintering temperature reaches 1,200℃ or higher,the 1,500℃ flexural strength can be measured,which increases as the sintering temperature rises.The core exhibits excellent creep resistance when sintered at temperatures of 1,200℃ and above.Considering the comprehensive performance requirements for the core,the sintering temperature of 1,200℃ was selected.At the sintering temperature of 1,200℃,the core exhibits shrinkage rates of 3.76%(X),3.38%(Y),and 3.95%(Z),alongside a flexural strength of 9.01 MPa at 25℃ and 32.15 MPa at 1,500℃,and an open porosity of 26.39%.The deflection of the core at 1,500℃ is 0.15 mm,which helps to maintain the dimensional stability of the ceramic core during casting.XRD results indicate that samples fractured after 25℃ flexural strength test still contain amorphous quartz glass,alongside substantial quantities of yttria stabilized zirconia and Y_(2)O_(3).Samples fractured after 1,500℃ flexural strength test exhibit significant crystallisation of amorphous quartz glass into cristobalite,with silica and 3YSZ combining to form ZrSiO_(4).Y_(2)O_(3) as a network modifier of the glass network destroys the bridging oxygen in the silica-oxygen bond,thereby reducing the energy required for glass crystallisation and promoting the crystallisation reaction of quartz glass to form cristobalite.In addition,nano-3YSZ combines with SiO_(2) at high temperatures to form ZrSiO_(4).Since cristobalite and ZrSiO_(4) are crystals,both of them have strong creep resistance,thus improving the high temperature flexural strength and deformation resistance of the ceramic cores.
文摘物种是生物多样性的基本单元,生殖隔离被认为是物种形成的关键;然而物种并不是静止的而是处于不断的分化演变之中,已经稳定成型但尚未到达分化后期的物种可能存在不完全的生殖隔离。对于物种的认识不能单从某一侧面或局部特征来界定,而应通过"整合物种概念"来确定物种地位。Flora of China记载了中国产白桫椤属(Sphaeropteris)2种,即白桫椤(S.brunoniana)和笔筒树(S.lepifera),并认为原产中国海南的海南白桫椤(S.hainanensis)和白桫椤为同一物种而将其并入白桫椤;但海南白桫椤在形态上已出现了分化。为探讨白桫椤及其近缘物种的亲缘关系和物种多样性分化的情况,本文采集到9个居群共21个样本,通过GBS简化基因组测序技术获得单核苷酸变异位点(SNP),进行系统发育树的构建和主成分及遗传结构的分析,并结合叶片数量性状的统计分析和孢子形态的观察测量。结果表明,海南白桫椤不仅与云南产白桫椤的基因型不同,且在叶片特征和孢子纹饰上有明显差异;但两个居群的生殖隔离较弱,在广西沿海地区形成杂交产物,其叶片特征为亲本的中间类型。因此,我们认为海南白桫椤是由于地理隔离而形成的一个处在分化路上的物种,建议恢复其物种地位;广西产白桫椤为自然杂交群体,应另处理为独立的自然杂交分类群--广西白桫椤(S. brunoniana×hainanensis)。
基金Supported by grants from the Science and Technology Department of Sichuan Province,No.2011SZ0094
文摘AIM: To investigate the roles of nuclear factor(NF)-κB and angiotensin Ⅱ receptor type 1(AT1R) in the pathogenesis of non-alcoholic fatty liver disease(NAFLD).METHODS: Forty-two healthy adult male SpragueDawley rats were randomly divided into three groups:the control group(normal diet), the model group,and the intervention group(10 wk of a high-fat diet feeding, followed by an intraperitoneal injection of PDTC); 6 rats in each group were sacrificed at 6, 10,and 14 wk. After sacrifice, liver tissue was taken,paraffin sections of liver tissue specimens were prepared, hematoxylin and eosin(HE) staining was performed, and pathological changes in liver tissue(i.e., liver fibrosis) were observed by light microscopy.NF-κB expression in liver tissue was detected by immunohistochemistry, and the expression of AT1 R in the liver tissue was detected by reverse transcriptionpolymerase chain reaction(RT-PCR). The data are expressed as mean ± SD. A two-sample t test was used to compare the control group and the model group at different time points, paired t tests were used to compare the differences between the intervention group and the model group, and analysis of variance was used to compare the model group with the control group. Homogeneity of variance was analyzed with single factor analysis of variance. H variance analysis was used to compare the variance. P < 0.05 wasconsidered statistically significant.RESULTS: The NAFLD model was successful after 6wk and 10 wk. Liver fibrosis was found in four rats in the model group, but in only one rat in the intervention group at 14 wk. Liver steatosis, inflammation, and fibrosis were gradually increased throughout the model. In the intervention group, the body mass,rat liver index, serum lipid, and transaminase levels were not increased compared to the model group.In the model group, the degree of liver steatosis was increased at 6, 10, and 14 wk, and was significantly higher than in the control group(P < 0.01). In the model group, different degrees of liver cell necrosis were visible and small leaves, punctated inflammation,focal necrosis, and obvious ballooning degeneration were observed. Partial necrosis and confluent necrosis were observed. In the model group, liver inflammatory activity scores at 6, 10, and 14 wk were higher than in the control group(P < 0.01). Active inflammation in liver tissue in the intervention group was lower than in the model group(P < 0.05). HE staining showed liver fibrosis only at 14 wk in 4/6 rats in the model group and in 1/6 rats in the intervention group. NF-κB positive cells were stained yellow or ensemble yellow,and NF-κB was localized in the cytoplasm and/or nucleus. The model group showed NF-κB activation at6, 10, and 14 wk in liver cells; at the same time points,there were statistically significant differences in the control group(P < 0.01). Over time, NF-κB expression increased; this was statistically lower(P < 0.05) at14 weeks in the intervention group compared to the model group, but significantly increased(P < 0.05)compared with the control group; RT-PCR showed that AT1 R mRNA expression increased gradually in the model group; at 14 wk, the expression was significantly different compared with expression at 10 weeks as well as at 6 weeks(P < 0.05). In the model group, AT1 R mRNA expression was significantly higher than at the same time point in the control group(P <0.01).CONCLUSION: With increasing severity of NAFLD,NF-κB activity is enhanced, and the inhibition of NF-κB activity may reduce AT1 R mRNA expression in NAFLD.
基金the National Natural Science Foundation of China(Nos.11605171 and 21973076)Sichuan Science and Technology Program(No.2018GZ0155)+2 种基金Ph.D program Foundation of SWUST(No.18ZX7112)Longshan Program for Talents(SWUST,No.I8 LZXT11)the Project of State Key Laboratory of Environment-Friendly Energy Materials(SWUST,No.19FKSY16).
文摘The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica.Nevertheless,the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques.Herein,small-angle neutron scattering(SANS)and synchrotron radiation X-ray nano-computed tomography(Nano-CT)techniques are employed to explore the evolution of filler networks of fumed,precipitated and sol-gel silica,respectively.Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates.And the silica with highly associated structure,pertaining to amorphous morphology,small size,and large surface area,presents short distance and effective molecular chain bridge between aggregates,thus forming strong and steady filler networks.This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.
基金supported by Key-Area Research and Development Program of Guangdong Province(Grant No.2022B1111230001)National Natural Science Foundation of China(31860048).
文摘Understanding genome-wide diversity,inbreeding,and the burden of accumulated deleterious mutations in small and isolated populations is essential for predicting and enhancing population persistence and resilience.However,these effects are rarely studied in limestone karst plants.Here,we re-sequenced the nuclear genomes of 62 individuals of the Begonia masoniana complex(B.liuyanii,B.longgangensis,B.masoniana and B.variegata)and investigated genomic divergence and genetic load for these four species.Our analyses revealed four distinct clusters corresponding to each species within the complex.Notably,there was only limited admixture between B.liuyanii and B.longgangensis occurring in overlapping geographic regions.All species experienced historical bottlenecks during the Pleistocene,which were likely caused by glacial climate fluctuations.We detected an asymmetric historical gene flow between group pairs within this timeframe,highlighting a distinctive pattern of interspecific divergence attributable to karst geographic isolation.We found that isolated populations of B.masoniana have limited gene flow,the smallest recent population size,the highest inbreeding coefficients,and the greatest accumulation of recessive deleterious mutations.These findings underscore the urgency to prioritize conservation efforts for these isolated population.This study is among the first to disentangle the genetic differentiation and specific demographic history of karst Begonia plants at the whole-genome level,shedding light on the potential risks associated with the accumulation of deleterious mutations over generations of inbreeding.Moreover,our findings may facilitate conservation planning by providing critical baseline genetic data and a better understanding of the historical events that have shaped current population structure of rare and endangered karst plants.
基金the support of the National Natural Science Foundation of China(Grant Nos.52274337 and 52174317)。
文摘To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn and Al contents in the steel and the reaction time on the interfacial reaction were investigated.It was observed that the erosion of the MgO refractory is caused by the reaction of Al and Mn in the steel with MgO in the refractory,which would lead to the formation of(Mn,Mg)O·Al_(2)O_(3) spinel and(Mn,Mg)O solid solution.The formation mechanism of the spinel and solid solution is as follows.The Al in the steel firstly reacts with MgO in the refractory to generate MgO·Al_(2)O_(3) spinel,and then,the spinel reacts with Mn in the steel to form(Mn,Mg)O·Al_(2)O_(3) spinel.Finally,the MnO in the spinel reacts with the MgO in the inner refractory to form(Mn,Mg)O solid solution.In addition,only(Mn,Mg)O·Al_(2)O_(3) spinel is present in the interfacial reaction layer of the refractory when the Al content in the steel is sufficient.
基金supported by the National Natural Science Foundation of China(Grant No.11005080)
文摘By using a simplified Coulomb explosion model, the laser-driven Coulomb explosion processes of three deuterated alkane clusters, i.e., deuterated methane（CD4）N, ethane（C2D6）N and propane（C3D8）N clusters are simulated numerically.The overrun phenomenon that the deuterons overtake the carbon ions inside the expanding clusters, as well as the dependence of the energetic deuterons and fusion neutron yield on cluster size, is discussed in detail. Researches show that the average kinetic energy of deuterons and neutron yield generated in the Coulomb explosion of（C2D6）N cluster are higher than those of（CD4）N cluster with the same size, in qualitative agreement with the reported conclusions from the experiments of（C2 H6）N and（CH4）N clusters. It is indicated that（C2D6）N clusters are superior to（CD4）N clusters as a target for the laser-induced nuclear fusion reaction to achieve a higher neutron yield. In addition, by comparing the relevant data of（C3D8）N cluster with those of（C2D6）N cluster with the same size, it is theoretically concluded that（C3D8）N clusters with a larger competitive parameter might be a potential candidate for improving neutron generation. This will provide a theoretical basis for target selection in developing experimental schemes on laser-driven nuclear fusion in the future.
基金supported by Guangdong Flagship Project of Basic and Applied Basic Research(2023B0303050001)Biological Resources Program,Chinese Academy of Sciences(KFJ-BRP-007-012)the National Natural Science Foundation of China(32170237,31760061)。
文摘Both biotic and abiotic factors are expected to drive species diversification,yet demonstrating their synergistic effects within a single framework is challenging and has rarely been studied.The recent and rapid radiation of the genus Aspidistra(cast-iron plant)provides an ideal system for examining these processes.Here,we generated restriction site-associated DNA sequencing data for 123 Aspidistra taxa and reconstructed wellresolved phylogenies using both concatenationand coalescent-based approaches.Using a comprehensive suite of diversification models,we quantified the contributions of multiple biotic and abiotic factors and applied phylogenetic path analysis to detect their synergistic effects.Our phylogenetic analyses recovered two main clades that differ in stem habits.We found that the diversification of Aspidistra has been driven by both abiotic factors(paleotemperature and the East Asian monsoon)and biotic factors(interspecific competition and pollination mutualism).Notably,these drivers operated both independently and synergistically to facilitate the rapid radiation of Aspidistra.Beyond providing a robust phylogeny useful for classifying Aspidistra,we present a statistical framework for better understanding the macroevolutionary processes underlying rapid plant radiations.Our findings underscore the critical importance of integrating multiple biotic and abiotic drivers into a unified analytical framework to comprehensively understand diversification history.
基金supported by the National Natural Science Foundation of China(Nos.11974259 and 12274241)。
文摘Polarization singularities beyond the bound states in the continuums(BICs)have garnered significant interest due to their potential for light manipulation.The conservation of topological charge has proven crucial in various photonic systems,and it guides the behavior of these singularities,including the generation and annihilation of BICs.This work theoretically reveals the simultaneous generation of two distinct polarization singularity types,which include off-Γaccidental BICs and Dirac-type band degeneracy points.The generation is driven by a quadratic degeneracy of symmetry-protected BICs in a photonic crystal slab.It should be noted that this is achieved through continuously tuning a geometric parameter without breaking symmetry.Importantly,the generation of both singularity types can be explained by the topological charge conservation law.This adherence ensures the stability of these singularities and allows for continuous tuning of their positions in momentum space by continuously tuning a geometric parameter while preserving symmetry.This study presents a novel framework for synthesizing and manipulating complex polarization states by combining polarization singularities from both BICs and band degeneracies and holds promise for application in other wave systems beyond photonics.
基金supported by the National Natural Science Foundation of China(21171110)the Natural Science Foundation of Science and Technology Agency of Shanxi Province(20210302123324,201901D111275)+1 种基金the Graduate Education Innovation Project of Shanxi Province(2024XBY05)the 1331 Project of Shanxi Province.
文摘Due to high penetration,low photo-toxicity,and low background signal of red-shifted visible light,the development of visible-light photochromic materials is of great importance but still a challenging task.In this study,four one-dimensional(1D)naphthalenediimide(NDI)photochromic coordination polymers(CPs),namely{[ZnCl_(2)(4-PMNDI)]·H_(2)O}_(n)(1),{[ZnBr_(2)(4-PMNDI)]·2H_(2)O}_(n)(2),{[ZnCl_(2)(3-PMNDI)]}_(n)(3)and{[ZnBr_(2)(3-PMNDI)]}_(n)(4)(4-/3-PMNDI=N,N’-bis(4-/3-pyridylmethyl)-1,4,5,8-naphthalenediimide),have been designed and synthesized by the combination of positional isomeric electron-deficient PMNDI(electron acceptors,EAs)and electron-rich zinc halides(electron donors,EDs)under solvothermal conditions.The distinct photochromic properties of 1-4 should be attributed to the formation of different interfacial contacts of EDs/EAs due to the introduction of 4-/3-PMNDI positional isomers and different halogen anions.Noteworthily,the much more rapid photoresponsive rates of visible-light photochromism for 1-4 with respect to those of UV-light photochromism exposits that the electronic absorption band of charge transfer(CT)interactions in the visible light region can effectively trigger electron transfer(ET)promptly.Furthermore,1 exhibits a high photosensitivity property in response to wavelengths of 390-450 nm,and it can be applied in detection/filtration of harmful blue rays.This work breaks through an orthodox concept that the ET reaction can only be activated by the electronic absorption band of EDs or EAs(usually in the UV light region),and provides a simple and feasible method for the construction of visible-light photochromic materials.
基金Supported by the National Natural Science Foundation of China （30370153）, and the Key Project of the Knowledge Innovation of the Chinese Academy of Sciences （KSCX2-SW-104）.
文摘Spontaneous hybridization in ex situ facilities can undermine the genetic integrity of ex situ collections and potentially contaminate open-pollinated seeds or seedlings destined for the reintroduction of endangered plant species into the wild. In the present study, the potential risk of hybridization between two endangered Chinese endemic species, namely Sinojackia xylocarpa Hu and S. rehderiana Hu, which are naturally allopatric species but were conserved ex situ in Wuhan Botanical Garden （WBG）, Wuhan, China, were investigated over three consecutive years from 2003 to 2005. The entire overlapping flowering period of the two species was 14-20 d and the two species shared the same pollinator insects during the entire flowering season in WBG. The floral isolation between the two species was not an issue in the ex sltu collection at WBG. The results suggest an opportunity for pollen transfer between species and a potential risk of genetic Introgression and loss of genetic identity of open-pollinated seeds produced in the ex sltu Collection of these two endangered species. An artificial reciprocal cross between S xylocarpa and S. rehderlana confirmed that the two congener species could readily set seeds, indicating no post-pollination barriers to hybridization and the importance of spatial isolation as a barrier to inter-specific crossing. Therefore, to manage these crossable species with overlapping flowering times and shared pollination vectors in ex situ facilities, spatial isolation should be carefully considered to minimize the possibility of spontaneous hybridization.
基金supported by the National Natural Science Foundation of China (Grant Nos. 62005193, 61805129, 62075158, and 11874245)Key Research and Development Program of Shanxi Province (Grant No. 201903D121026)+1 种基金Tianjin Municipal Fund for Distinguished Young Scholars (Grant No. 18JCJQJC45600)partially supported by the Air Force Office of Scientific Research and the Simons Foundation
文摘Metasurfaces have enabled the realization of several optical functionalities over an ultrathin platform,fostering the exciting field of flat optics.Traditional metasurfaces are achieved by arranging a layout of static meta-atoms to imprint a desired operation on the impinging wavefront,but their functionality cannot be altered.Reconfigurability and programmability of metasurfaces are the next important step to broaden their impact,adding customized on-demand functionality in which each meta-atom can be individually reprogrammed.We demonstrate a mechanical metasurface platform with controllable rotation at the meta-atom level,which can implement continuous Pancharatnam–Berry phase control of circularly polarized microwaves.As the proof-of-concept experiments,we demonstrate metalensing,focused vortex beam generation,and holographic imaging in the same metasurface template,exhibiting versatility and superior performance.Such dynamic control of electromagnetic waves using a single,low-cost metasurface paves an avenue towards practical applications,driving the field of reprogrammable intelligent metasurfaces for a variety of applications.
基金supported by the National Natural Science Foundation of China (NSFC)(No.11874228)。
文摘We show that inhomogeneous waveguides of slowly varied parity-time(PT) symmetry support localized optical resonances.The resonance is closely related to the formation of exceptional points separating exact and broken PT phases.Salient features of this kind of non-Hermitian resonance, including the formation of half-vortex flux and the discrete nature,are discussed.This investigation highlights the unprecedented uniqueness of field dynamics in non-Hermitian systems with many potential adaptive applications.
