THE next time people see an adventure sci-fi movie like Hollywood＇s Jurassic Park, dinosaurs in the movie may look very different, especially the Tyrannosaurus rex. They could be feathered,
Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km 2 and consist of crescent sand ridges and interridge tongue-shaped dunes.Differences in grain size,mineral composition and alb...Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km 2 and consist of crescent sand ridges and interridge tongue-shaped dunes.Differences in grain size,mineral composition and albedo between crescent sand ridges and tongue-shaped dunes,and between windward and leeward slopes of tongue-shaped dunes,result in their feathery appearance in aerial and satellite imagery.Measurements of the sand drift potential in the region show that the sand-moving wind for feathered sand ridges can be divided into three sectors;i.e.north-northeasterly,easterly and east-northeasterly sectors roughly corresponding to the southeast,northwest and southwest slip faces.Our findings suggests that the crescent sand ridges resulting from the connection of barchan dunes along the prevailing wind direction are longitudinal dune ridges rather than transverse ones.Tongue-shaped dunes and quasi-dune shapes have obvious distinctions and are new transverse dune types.According to McKee's dune shape classification,the feathered sand ridges are not a deformation dune type but a complex one.According to Wu's dune morphological and genetic classification,they are not dune ridges or compound dune ridges that form under the action of unidirectional winds or two winds intersecting at an acute angle,but are complex dune ridges that form under the action of three winds intersecting at an acute angle.展开更多
Recent discoveries of feathered dinosaurs from Early Cretaceous deposits in Liaoning,China,have not only lent strongest support for the dinosaurian hypothesis of bird origins,but have also provided much-needed informa...Recent discoveries of feathered dinosaurs from Early Cretaceous deposits in Liaoning,China,have not only lent strongest support for the dinosaurian hypothesis of bird origins,but have also provided much-needed information about the origins of feathers and avian flight.Preliminary analysis of character evolution suggests that the major avian osteological characters were acquired during the early evolution of maniraptoran dinosaurs.The available evidence also suggests that the first feathers with a filamentous morphology probably evolved in basal coelurosaurs and pennaceous feathers(including those with aerodynamic features)were developed in non-avian maniraptorans,indicating that feathers evolved before the origin of birds and their flight.An evolutionary model is proposed here to describe the major stages of feather evolution,a process characterized by a combination of both transformational and innovative modifications.This model is different from some recent developmental models,which suggest that feathers are evolutionary novelties without a homologous relationship to reptilian scales.Although non-avian theropods are traditionally regarded as distinctly cursorial animals,recent discoveries suggest that the closest relatives of birds might be arboreal theropods.Many bird features,such as the furcula and pennaceous feathers,evolved in a terrestrial context,whereas others,such as some pedal modifications,may have evolved in an arboreal context.Consequently,arboreality may have also contributed to the origin of avian flight.展开更多
Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are kn...Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are known for their unique compact structure;they are not only lightweight but also strong.In this study,an in-depth look at owl feathers was made and it found that owl feathers not only have the macro branches structure between feather shafts and branches but also have fine feather structures on the branches.The presence of these fine feather structures increases the specific surface area of the plume branches and allows neighboring plume branches to hook up with each other,forming an effective mechanical interlocking structure.These structures bring owl feathers excellent mechanical properties.Inspired by the natural structure of owl feathers,a weaving technique and a sizing process were combined to prepare bionic Carbon Fiber(CF)fabrics and then to fabricate the bionic CFRP with structural characteristics similar to owl feathers.To evaluate the effect of the fine feather structure on the mechanical properties of CFRP,a mechanical property study on CFRP with and without the fine feather imitation structure were conducted.The experimental results show that the introduction of the fine feather branch structure enhance the mechanical properties of CFRP significantly.Specifically,the tensile strength of the composites increased by 6.42%and 13.06%and the flexural strength increased by 8.02%and 16.87%in the 0°and 90°sample directions,respectively.These results provide a new design idea for the improvement of the mechanical properties of the CFRP,promoting the application of CFRP in engineering fields,such as automotive transportation,rail transit,aerospace,and construction.展开更多
The number of secondary feathers varies among orders of birds with some orders exhibiting a positive relationship with ulna length,whereas in other orders secondary number is invariant.This difference has implications...The number of secondary feathers varies among orders of birds with some orders exhibiting a positive relationship with ulna length,whereas in other orders secondary number is invariant.This difference has implications for scaling of the width of the feather vane within orders.In those species where the number of secondary remiges is invariant with ulna length,vane width should scale isometrically with ulna size to maintain an aerodynamic flight surface.Where feather count increases with increasing ulna length then vane width should exhibit negative allometry.Vane length should also correlate with ulna length,irrespective of the number of feathers.Data were compiled from an online library of images for the vane length and the width of the vane at 50%of the vane length for the fifth secondary feather for 209 bird species from 24 different orders.The results supported the hypotheses that vane width is a function of ulna size,and the number of secondary feathers as associated with different orders.Vane length was unaffected by the number of secondaries but varied between orders.The results suggest that birds have solved the problem of maintaining the aerodynamic surface of the proximal wing in two ways.Hence as ulna length increases the first solution involves more feathers that exhibit negative allometry for vane width,or in the second where feather count doesn't change,the vane width simply scales isometrically.The implications for the mechanical properties of the vane,and how it affects wing function,have not yet been explored in a range of birds.展开更多
Powered fight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures.Many basic aspects of feather functionality are unknown,which hampers our understanding of wing function in birds...Powered fight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures.Many basic aspects of feather functionality are unknown,which hampers our understanding of wing function in birds.This study measured the dimensions of primary and secondaryfight feathers of 19 species of parrots.The maximum force the feathers could withstand from below was also measured to mimic the pressuresexperienced during a downstroke.The analysis tested whether:(1)feather dimensions differed along the wing and among secondary and primary remiges;(2)the force that feathers could withstand varied among the remiges;and(3)there would be isometric relationships with bodymass for feather characteristics.The results show that body mass signifcantly affected vane width,rachis thickness,maximum force,and ultimate bending moment,but the relationship for feather length only approached signifcance.Many of the proximal secondary feathers showedsignifcantly lower values relative to the frst primary,whereas for distal primaries the values were greater.There were isometric relationships forforce measurements of primary and secondary feathers with body mass,but there was positive allometry for feather lengths and vane widths.The forces feathers can withstand vary along the wing may be a proxy for the aerodynamic properties of the feathers in situ.Broader taxonomicstudies that explore these topics are required for other species representing a range of different orders.A better understanding of the functionality of feathers will improve our understanding of how avian fight works particularly considering the variety in fight style and wing shape in birds.展开更多
Fire disturbances are increasing under global climate change and ecological transformations of forests are occurring.Specifically,shifts from productive closed-canopy feather moss forests to low-productivity open-cano...Fire disturbances are increasing under global climate change and ecological transformations of forests are occurring.Specifically,shifts from productive closed-canopy feather moss forests to low-productivity open-canopy lichen(Cladonia spp.)woodlands have been observed in boreal forests of eastern Canada.It has been hypothesized that high severity of fires would be the cause of this change,but this is difficult to validate a posteriori on mature forest stands.Because charcoal properties are affected by fire severity,we have put forward the hypothesis that the amount and physicochemical properties of charcoal(C,N,H,O,ash,surface area)would be different and indicative of a greater fire severity for open-canopy forests compared to closed canopy ones.Our hypothesis was partly validated in that the amount of charcoal found on the ground of closed-canopy forests was greater than that of open-canopy forests.However,the physicochemical properties were not different,albeit a greater variability of charcoal properties for open canopy stands.These results do not allow us to fully validate or reject our hypothesis on the role of fire severity in the shift between open and closed canopy stands.However,they suggest that the variability in fire conditions as well as the amounts of charcoal produced are different between the two ecosystem types.Furthermore,considering the role that biochar may play in improving soil conditions and promoting vegetation restoration,our results suggest that charcoal may play a role in maintaining these two stable alternative ecosystem states.展开更多
Taking a widely contaminated yet abundant waste,such as poultry feathers,and extracting keratin from this struc-ture appears to be a real challenge whenever the preservation of the secondary structure of the protein i...Taking a widely contaminated yet abundant waste,such as poultry feathers,and extracting keratin from this struc-ture appears to be a real challenge whenever the preservation of the secondary structure of the protein is desired.This process would allow exploiting it in ways(e.g.,in the biomedicalfield)that are inspired by a structure that is primarily designed forflight,therefore capable specifically of withstandingflexure and lateral buckling,also with very low thicknesses.The preservation of the structure is based on disulfide crosslinks,and it is offered with pre-ference by some chemical treatments,mainly those based on ionic liquid and on a reduction process.However,the degree of preservation cannot always be precisely assessed;however,beyond chemical characterization,the forma-tion of homogeneous gels can also suggest that the process was successful in this sense.An extraction respectful of nature’s intentions,considering that the secondary structure builds up according to the very function of the feath-ers in the animal,can be deemed to be biomimetic.In particular,biomimetic extractions comply with the very characteristics the protein was designed for to serve in the specific environmental and mechanical situation in which it is inserted.This review tries to elucidate in which cases this aim is achieved and for which specific appli-cations a chicken feather keratin that has preserved its secondary structure can be suited.展开更多
Background Poor feather growth not only affects the appearance of the organism but also decreases the feed efficiency.Methionine(Met)is an essential amino acid required for feather follicle development;yet the exact m...Background Poor feather growth not only affects the appearance of the organism but also decreases the feed efficiency.Methionine(Met)is an essential amino acid required for feather follicle development;yet the exact mechanism involved remains insufficiently understood.Methods A total of 1801-day-old broilers were selected and randomly divided into 3 treatments:control group(0.45%Met),Met-deficiency group(0.25%Met),and Met-rescue group(0.45%Met in the pre-trial period and 0.25%Met in the post-trial period).The experimental period lasted for 56 d,with a pre-trial period of 1–28 d and a post-trial period of 29–56 d.In addition,Met-deficiency and Met-rescue models were constructed in feather follicle epidermal stem cell by controlling the supply of Met in the culture medium.Results Dietary Met-deficiency significantly(P<0.05)reduced the ADG,ADFI and F/G,and inhibited feather follicle development.Met supplementation significantly(P<0.05)improved growth performance and the feather growth in broilers.Met-rescue may promote feather growth in broilers by activating the Wnt/β-catenin signaling pathway(GSK-3β,CK1,Axin1,β-catenin,Activeβ-catenin,TCF4,and Cyclin D1).Compared with Met-deficiency group,Met-rescue significantly(P<0.05)increased the activity of feather follicle epidermal stem cell and mitochondrial membrane potential,activated Wnt/β-catenin signaling pathway,and decreased the content of reactive oxygen species(P<0.05).CO-IP confirmed that mitochondrial protein PGAM5 interacted with Axin1,the scaffold protein of the disruption complex of the Wnt/β-catenin signaling pathway,and directly mediated Met regulation of Wnt/β-catenin signaling pathway and feather follicle development.Conclusions PGAM5 binding to Axin1 mediates the regulation of Wnt/β-catenin signaling pathway,and promotes feather follicle development and feather growth of broiler chickens through Met supplementation.These results provide theoretical support for the improvement of economic value and production efficiency of broiler chickens.展开更多
A duxianqin musician needs only a single string stretched across an elongated(细长的)soundboard and a feather⁃shaped rod to deliver a diverse repertoire,whether pop or classical,Chinese or Western.In his Zen⁃style stu...A duxianqin musician needs only a single string stretched across an elongated(细长的)soundboard and a feather⁃shaped rod to deliver a diverse repertoire,whether pop or classical,Chinese or Western.In his Zen⁃style studio adorned with folding screens,Wei Qingbing,39,sits on a bamboo mat and plucks(弹拨)the string of his duxianqin with his right hand,while his left hand slides across the rod to adjust the pitch and add vibrato.展开更多
Flight feathers represent a hallmark innovation of avian evolution.Recent comparative genomic analyses identified a 284 bp avian-specific highly conserved element(ASHCE)located within the eighth intron of the SIM bHLH...Flight feathers represent a hallmark innovation of avian evolution.Recent comparative genomic analyses identified a 284 bp avian-specific highly conserved element(ASHCE)located within the eighth intron of the SIM bHLH transcription factor 1(Sim1)gene,postulated to act as a cis-regulatory element governing flight feather morphogenesis.To investigate its functional significance,genome-edited(GE)primordial germ cell(PGC)lines carrying targeted ASHCE deletions were generated using CRISPR/Cas9-mediated editing,with germline chimeric males subsequently mated with wild-type(WT)hens to obtain GE progeny.The resulting GE chickens harbored 257-260 bp deletions,excising approximately half of the Sim1-ASHCE sequence.Reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR)analysis showed an average 0.32-fold reduction in Sim1 expression in the forelimbs of GE embryos at day 8(E8)compared to WT counterparts.Despite this,GE chickens developed structurally normal flight and tail feathers.In situ hybridization localized Sim1 expression to the posterior mesenchyme surrounding flight feather buds in E8 WT embryos,but not within the buds themselves.These results suggest that partial deletion of Sim1-ASHCE,despite diminishing Sim1 expression,does not disrupt flight feather formation.The excised region appears to possess enhancer activity toward Sim1 but is dispensable for flight feather development.Complete ablation of the ASHCE will be necessary to fully resolve the regulatory role of Sim1 in avian feather morphogenesis.展开更多
[Objective]This study aimed to explore the inheritance pattem of feather color in hybrid offspring of Texan pigeon and American Silver King pigeon, so as to provide a theoretical basis for the breeding of feather colo...[Objective]This study aimed to explore the inheritance pattem of feather color in hybrid offspring of Texan pigeon and American Silver King pigeon, so as to provide a theoretical basis for the breeding of feather color auto-sexing strains. [Method]The segregation situation of feather color in the male and female offspring of Texan pigeon （♂）×American Silver King pigeon （♀）（TKYW） and American Silver King pigeon （♂） ×Texan pigeon （♀） （YWTK） was analyzed. [Result]The feather color of TKYW offspring was all slate gray. Among the offspring of YWTK, the feather color of the males was all slate gray, while the feather color of the females was all silver gray; and the ratio between different colors was 1：1 （P 〉 0.05）. The F1 generation of YWTK was subjected to selfing, and the feather color of the male and female F2 generation was analyzed. It was found that the ratio of silver gray （male） to slate gray （male） to silver gray （female） to slate gray （female） was 1：1：1：1 （P 〉 0.05）. On the basis of the above results, it could be preliminarily predicated that the feather color control genes of Texan pigeon are Z^BZB and Z^BW and those of American Silver King pigeon are Z^bZ^b and Z^bW. There is a cumulative effect on B which is dominant for b. [Conclusion] This study will better solve the problem of male and female identification of pigeon in the early period.展开更多
Anchiornis huxleyi, which is a member of the Middle-Late Jurassic Yanliao Biota, is the smallest feathered dinosaur ever known. It has been described as a critical link between feathered dinosaurs and birds. Recent st...Anchiornis huxleyi, which is a member of the Middle-Late Jurassic Yanliao Biota, is the smallest feathered dinosaur ever known. It has been described as a critical link between feathered dinosaurs and birds. Recent studies, including those of Anchiornis, Xiaotingia, Eosinopteryx and Aurornis, challenged Archaeopteryx as the most basal bird. The new Anchiornis huxleyi specimens that are described in this paper show some minor different characters compared to previously reported Anchiornis specimens, which has revised the character list of Anchiornis and indicates a different phylogenetic point from former opinions.展开更多
Exposures of strata spanning the Jurassic–Cretaceous boundary occur within several basins in western Liaoning and adjacent Inner Mongolia.These continental successions host world-renowned plant and animal fossils inc...Exposures of strata spanning the Jurassic–Cretaceous boundary occur within several basins in western Liaoning and adjacent Inner Mongolia.These continental successions host world-renowned plant and animal fossils including feathered dinosaurs and the oldest flowering plant,Archaeofructus.The first feathered dinosaurs from northeastern China where found about 20 years ago and created a major impact in science and the media.Since then,many new specimens have been discovered.展开更多
In present,there are increasing interests in the research on mechanical and control system of underwater vehicles.These ongoing research efforts are motivated by more pervasive applications of such vehicles including ...In present,there are increasing interests in the research on mechanical and control system of underwater vehicles.These ongoing research efforts are motivated by more pervasive applications of such vehicles including seabed oil and gas explorations, scientific deep ocean surveys,military purposes,ecological and water environmental studies,and also entertainments. However,the performance of underwater vehicles with screw type propellers is not prospective in terms of its efficiency and maneuverability.The main weaknesses of this kind of propellers are the production of vortices and sudden generation of thrust forces which make the control of the position and motion difficult. On the other hand,fishes and other aquatic animals are efficient swimmers,posses high maneuverability,are able to follow trajectories,can efficiently stabilize themselves in currents and surges,create less wakes than currently used underwater vehicle, and also have a noiseless propulsion.The fish's locomotion mechanism is mainly controlled by its caudal fin and paired pectoral fins.They are classified into Body and/or Caudal Fin(BCF)and Median and/or paired Pectoral Fins(MPF).The study of highly efficient swimming mechanisms of fish can inspire a better underwater vehicles thruster design and its mechanism. There are few studies on underwater vehicles or fish robots using paired pectoral fins as thruster.The work presented in this paper represents a contribution in this area covering study,design and implementation of locomotion mechanisms of paired pectoral fins in a fish robot.The performance and viability of the biomimetic method for underwater vehicles are highlighted through in-water experiment of a robotic fish.展开更多
A novel Al-14.1 Mg-0.47 Si-0.31 Sc-0.17 Zr alloy was applied in the printing process of selective laser melting(SLM),and the corresponding microstructural feature,phase identification,tensile properties and corrosion ...A novel Al-14.1 Mg-0.47 Si-0.31 Sc-0.17 Zr alloy was applied in the printing process of selective laser melting(SLM),and the corresponding microstructural feature,phase identification,tensile properties and corrosion behavior of the Al Mg Si Sc Zr alloy were studied in detail.As fabricated at 160 W and 200 mm/s,the Mg content of bulk sample decreased to 11.7 wt%due to the element vaporization at high energy density,and the density of this additively manufactured Al Mg Si Sc Zr alloy was 2.538 g/cm^(3),which is4.2%8.5%lighter than that of other SLM-processed Al alloys.After heat-treated(HT)at 325℃and 6 h,the microstructure was almost unchanged with an alternate distribution of fine equiaxed crystals and coarse columnar crystals.Nano-sized Al3(Sc,Zr)and Mg_(2)Si phases precipitated dispersedly in the Al matrix,and the tensile strength increased from 487.6 MPa to 578.4 MPa for precipitation strengthening and fine grain strengthening.With a fine grain size of 2.53μm,an excellent corrosion resistance was obtained for the as-printed(AP)Al Mg Si Sc Zr alloy.While the corrosion resistance of HT sample decreased slightly for the formation of non-dense oxide layer and pitting corrosion induced by diffuse precipitation distribution.This SLM-printed Al Mg Si Sc Zr alloy with high specific strength,good thermal stability and excellent corrosion resistance has broad prospects for the aerospace and automotive applications.展开更多
Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To re...Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To reveal the flying abilities, avian geometry of a golden eagle was extracted based on noncontact surface measurements using a ROMBER three-dimensional laser scanner. Distributions of a camber line, thickness and a secondary feather line of the extracted point cloud were fitted using convenient analytical expressions. A traditional airfoil was established with the camber line and thickness, then a combined airfoil was constructed by combining the traditional airfoil with a secondary feather. Oscillations of an airfoil as well as rapid pitch up were simplified as a sine wave around the quarter chord axis. Thereafter, both steady and unsteady aerodynamic performances of the airfoil are computed, the influences of the secondary feather on the steady and unsteady aerodynamics were further studied.展开更多
文摘THE next time people see an adventure sci-fi movie like Hollywood＇s Jurassic Park, dinosaurs in the movie may look very different, especially the Tyrannosaurus rex. They could be feathered,
基金supported by the National Basic Research Development of China(Grant No.2007CB407203)the National Scientific&Technical Basic Work Program(Grant No.2006FY110800)+1 种基金the National Natural Science Foundation of China(Grant No.49971013)the Gansu Provincial Natural Science Foundation(Grant No.0710RJZH084)
文摘Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km 2 and consist of crescent sand ridges and interridge tongue-shaped dunes.Differences in grain size,mineral composition and albedo between crescent sand ridges and tongue-shaped dunes,and between windward and leeward slopes of tongue-shaped dunes,result in their feathery appearance in aerial and satellite imagery.Measurements of the sand drift potential in the region show that the sand-moving wind for feathered sand ridges can be divided into three sectors;i.e.north-northeasterly,easterly and east-northeasterly sectors roughly corresponding to the southeast,northwest and southwest slip faces.Our findings suggests that the crescent sand ridges resulting from the connection of barchan dunes along the prevailing wind direction are longitudinal dune ridges rather than transverse ones.Tongue-shaped dunes and quasi-dune shapes have obvious distinctions and are new transverse dune types.According to McKee's dune shape classification,the feathered sand ridges are not a deformation dune type but a complex one.According to Wu's dune morphological and genetic classification,they are not dune ridges or compound dune ridges that form under the action of unidirectional winds or two winds intersecting at an acute angle,but are complex dune ridges that form under the action of three winds intersecting at an acute angle.
文摘Recent discoveries of feathered dinosaurs from Early Cretaceous deposits in Liaoning,China,have not only lent strongest support for the dinosaurian hypothesis of bird origins,but have also provided much-needed information about the origins of feathers and avian flight.Preliminary analysis of character evolution suggests that the major avian osteological characters were acquired during the early evolution of maniraptoran dinosaurs.The available evidence also suggests that the first feathers with a filamentous morphology probably evolved in basal coelurosaurs and pennaceous feathers(including those with aerodynamic features)were developed in non-avian maniraptorans,indicating that feathers evolved before the origin of birds and their flight.An evolutionary model is proposed here to describe the major stages of feather evolution,a process characterized by a combination of both transformational and innovative modifications.This model is different from some recent developmental models,which suggest that feathers are evolutionary novelties without a homologous relationship to reptilian scales.Although non-avian theropods are traditionally regarded as distinctly cursorial animals,recent discoveries suggest that the closest relatives of birds might be arboreal theropods.Many bird features,such as the furcula and pennaceous feathers,evolved in a terrestrial context,whereas others,such as some pedal modifications,may have evolved in an arboreal context.Consequently,arboreality may have also contributed to the origin of avian flight.
基金supported by the Science and Technology Development Program of Jilin Province(No.20240101122JC)and(No.20240101143JC)the Key Scientific and Technological Research and Development Projects of Jilin Provincial Science and Technology Department(Grant Number 20230201108GX)。
文摘Insufficient interfacial activity and poor wettability between fibers and matrix are the two main factors limiting the improvement of mechanical properties of Carbon Fiber Reinforced Plastics(CFRP).Owl feathers are known for their unique compact structure;they are not only lightweight but also strong.In this study,an in-depth look at owl feathers was made and it found that owl feathers not only have the macro branches structure between feather shafts and branches but also have fine feather structures on the branches.The presence of these fine feather structures increases the specific surface area of the plume branches and allows neighboring plume branches to hook up with each other,forming an effective mechanical interlocking structure.These structures bring owl feathers excellent mechanical properties.Inspired by the natural structure of owl feathers,a weaving technique and a sizing process were combined to prepare bionic Carbon Fiber(CF)fabrics and then to fabricate the bionic CFRP with structural characteristics similar to owl feathers.To evaluate the effect of the fine feather structure on the mechanical properties of CFRP,a mechanical property study on CFRP with and without the fine feather imitation structure were conducted.The experimental results show that the introduction of the fine feather branch structure enhance the mechanical properties of CFRP significantly.Specifically,the tensile strength of the composites increased by 6.42%and 13.06%and the flexural strength increased by 8.02%and 16.87%in the 0°and 90°sample directions,respectively.These results provide a new design idea for the improvement of the mechanical properties of the CFRP,promoting the application of CFRP in engineering fields,such as automotive transportation,rail transit,aerospace,and construction.
文摘The number of secondary feathers varies among orders of birds with some orders exhibiting a positive relationship with ulna length,whereas in other orders secondary number is invariant.This difference has implications for scaling of the width of the feather vane within orders.In those species where the number of secondary remiges is invariant with ulna length,vane width should scale isometrically with ulna size to maintain an aerodynamic flight surface.Where feather count increases with increasing ulna length then vane width should exhibit negative allometry.Vane length should also correlate with ulna length,irrespective of the number of feathers.Data were compiled from an online library of images for the vane length and the width of the vane at 50%of the vane length for the fifth secondary feather for 209 bird species from 24 different orders.The results supported the hypotheses that vane width is a function of ulna size,and the number of secondary feathers as associated with different orders.Vane length was unaffected by the number of secondaries but varied between orders.The results suggest that birds have solved the problem of maintaining the aerodynamic surface of the proximal wing in two ways.Hence as ulna length increases the first solution involves more feathers that exhibit negative allometry for vane width,or in the second where feather count doesn't change,the vane width simply scales isometrically.The implications for the mechanical properties of the vane,and how it affects wing function,have not yet been explored in a range of birds.
文摘Powered fight in birds is reliant on feathers forming an aerodynamic surface that resists air pressures.Many basic aspects of feather functionality are unknown,which hampers our understanding of wing function in birds.This study measured the dimensions of primary and secondaryfight feathers of 19 species of parrots.The maximum force the feathers could withstand from below was also measured to mimic the pressuresexperienced during a downstroke.The analysis tested whether:(1)feather dimensions differed along the wing and among secondary and primary remiges;(2)the force that feathers could withstand varied among the remiges;and(3)there would be isometric relationships with bodymass for feather characteristics.The results show that body mass signifcantly affected vane width,rachis thickness,maximum force,and ultimate bending moment,but the relationship for feather length only approached signifcance.Many of the proximal secondary feathers showedsignifcantly lower values relative to the frst primary,whereas for distal primaries the values were greater.There were isometric relationships forforce measurements of primary and secondary feathers with body mass,but there was positive allometry for feather lengths and vane widths.The forces feathers can withstand vary along the wing may be a proxy for the aerodynamic properties of the feathers in situ.Broader taxonomicstudies that explore these topics are required for other species representing a range of different orders.A better understanding of the functionality of feathers will improve our understanding of how avian fight works particularly considering the variety in fight style and wing shape in birds.
基金supported by the MITACS Accelerate grant with Greenfirst,industry partner in La Sarre,QC,Canada.
文摘Fire disturbances are increasing under global climate change and ecological transformations of forests are occurring.Specifically,shifts from productive closed-canopy feather moss forests to low-productivity open-canopy lichen(Cladonia spp.)woodlands have been observed in boreal forests of eastern Canada.It has been hypothesized that high severity of fires would be the cause of this change,but this is difficult to validate a posteriori on mature forest stands.Because charcoal properties are affected by fire severity,we have put forward the hypothesis that the amount and physicochemical properties of charcoal(C,N,H,O,ash,surface area)would be different and indicative of a greater fire severity for open-canopy forests compared to closed canopy ones.Our hypothesis was partly validated in that the amount of charcoal found on the ground of closed-canopy forests was greater than that of open-canopy forests.However,the physicochemical properties were not different,albeit a greater variability of charcoal properties for open canopy stands.These results do not allow us to fully validate or reject our hypothesis on the role of fire severity in the shift between open and closed canopy stands.However,they suggest that the variability in fire conditions as well as the amounts of charcoal produced are different between the two ecosystem types.Furthermore,considering the role that biochar may play in improving soil conditions and promoting vegetation restoration,our results suggest that charcoal may play a role in maintaining these two stable alternative ecosystem states.
文摘Taking a widely contaminated yet abundant waste,such as poultry feathers,and extracting keratin from this struc-ture appears to be a real challenge whenever the preservation of the secondary structure of the protein is desired.This process would allow exploiting it in ways(e.g.,in the biomedicalfield)that are inspired by a structure that is primarily designed forflight,therefore capable specifically of withstandingflexure and lateral buckling,also with very low thicknesses.The preservation of the structure is based on disulfide crosslinks,and it is offered with pre-ference by some chemical treatments,mainly those based on ionic liquid and on a reduction process.However,the degree of preservation cannot always be precisely assessed;however,beyond chemical characterization,the forma-tion of homogeneous gels can also suggest that the process was successful in this sense.An extraction respectful of nature’s intentions,considering that the secondary structure builds up according to the very function of the feath-ers in the animal,can be deemed to be biomimetic.In particular,biomimetic extractions comply with the very characteristics the protein was designed for to serve in the specific environmental and mechanical situation in which it is inserted.This review tries to elucidate in which cases this aim is achieved and for which specific appli-cations a chicken feather keratin that has preserved its secondary structure can be suited.
基金supported by the National Natural Science Foundation of China(32372902)Guangdong Special Support Program for Young Talents(NYQN2024007)。
文摘Background Poor feather growth not only affects the appearance of the organism but also decreases the feed efficiency.Methionine(Met)is an essential amino acid required for feather follicle development;yet the exact mechanism involved remains insufficiently understood.Methods A total of 1801-day-old broilers were selected and randomly divided into 3 treatments:control group(0.45%Met),Met-deficiency group(0.25%Met),and Met-rescue group(0.45%Met in the pre-trial period and 0.25%Met in the post-trial period).The experimental period lasted for 56 d,with a pre-trial period of 1–28 d and a post-trial period of 29–56 d.In addition,Met-deficiency and Met-rescue models were constructed in feather follicle epidermal stem cell by controlling the supply of Met in the culture medium.Results Dietary Met-deficiency significantly(P<0.05)reduced the ADG,ADFI and F/G,and inhibited feather follicle development.Met supplementation significantly(P<0.05)improved growth performance and the feather growth in broilers.Met-rescue may promote feather growth in broilers by activating the Wnt/β-catenin signaling pathway(GSK-3β,CK1,Axin1,β-catenin,Activeβ-catenin,TCF4,and Cyclin D1).Compared with Met-deficiency group,Met-rescue significantly(P<0.05)increased the activity of feather follicle epidermal stem cell and mitochondrial membrane potential,activated Wnt/β-catenin signaling pathway,and decreased the content of reactive oxygen species(P<0.05).CO-IP confirmed that mitochondrial protein PGAM5 interacted with Axin1,the scaffold protein of the disruption complex of the Wnt/β-catenin signaling pathway,and directly mediated Met regulation of Wnt/β-catenin signaling pathway and feather follicle development.Conclusions PGAM5 binding to Axin1 mediates the regulation of Wnt/β-catenin signaling pathway,and promotes feather follicle development and feather growth of broiler chickens through Met supplementation.These results provide theoretical support for the improvement of economic value and production efficiency of broiler chickens.
文摘A duxianqin musician needs only a single string stretched across an elongated(细长的)soundboard and a feather⁃shaped rod to deliver a diverse repertoire,whether pop or classical,Chinese or Western.In his Zen⁃style studio adorned with folding screens,Wei Qingbing,39,sits on a bamboo mat and plucks(弹拨)the string of his duxianqin with his right hand,while his left hand slides across the rod to adjust the pitch and add vibrato.
基金supported by the Ministry of Agriculture and Rural Affairs of the People's Republic of China(125A0607)Department of Science and Technology of Yunnan Province(XDYC-KJLJ-2022-0004)。
文摘Flight feathers represent a hallmark innovation of avian evolution.Recent comparative genomic analyses identified a 284 bp avian-specific highly conserved element(ASHCE)located within the eighth intron of the SIM bHLH transcription factor 1(Sim1)gene,postulated to act as a cis-regulatory element governing flight feather morphogenesis.To investigate its functional significance,genome-edited(GE)primordial germ cell(PGC)lines carrying targeted ASHCE deletions were generated using CRISPR/Cas9-mediated editing,with germline chimeric males subsequently mated with wild-type(WT)hens to obtain GE progeny.The resulting GE chickens harbored 257-260 bp deletions,excising approximately half of the Sim1-ASHCE sequence.Reverse transcription-quantitative real-time polymerase chain reaction(RT-qPCR)analysis showed an average 0.32-fold reduction in Sim1 expression in the forelimbs of GE embryos at day 8(E8)compared to WT counterparts.Despite this,GE chickens developed structurally normal flight and tail feathers.In situ hybridization localized Sim1 expression to the posterior mesenchyme surrounding flight feather buds in E8 WT embryos,but not within the buds themselves.These results suggest that partial deletion of Sim1-ASHCE,despite diminishing Sim1 expression,does not disrupt flight feather formation.The excised region appears to possess enhancer activity toward Sim1 but is dispensable for flight feather development.Complete ablation of the ASHCE will be necessary to fully resolve the regulatory role of Sim1 in avian feather morphogenesis.
基金Supported by Key Research and Development Program of Jiangsu Province(Modern Agriculture)(BE2017348)~~
文摘[Objective]This study aimed to explore the inheritance pattem of feather color in hybrid offspring of Texan pigeon and American Silver King pigeon, so as to provide a theoretical basis for the breeding of feather color auto-sexing strains. [Method]The segregation situation of feather color in the male and female offspring of Texan pigeon （♂）×American Silver King pigeon （♀）（TKYW） and American Silver King pigeon （♂） ×Texan pigeon （♀） （YWTK） was analyzed. [Result]The feather color of TKYW offspring was all slate gray. Among the offspring of YWTK, the feather color of the males was all slate gray, while the feather color of the females was all silver gray; and the ratio between different colors was 1：1 （P 〉 0.05）. The F1 generation of YWTK was subjected to selfing, and the feather color of the male and female F2 generation was analyzed. It was found that the ratio of silver gray （male） to slate gray （male） to silver gray （female） to slate gray （female） was 1：1：1：1 （P 〉 0.05）. On the basis of the above results, it could be preliminarily predicated that the feather color control genes of Texan pigeon are Z^BZB and Z^BW and those of American Silver King pigeon are Z^bZ^b and Z^bW. There is a cumulative effect on B which is dominant for b. [Conclusion] This study will better solve the problem of male and female identification of pigeon in the early period.
基金The National Natural Science Foundation of China(grant No.41372026)China Geological Survey(grant No.DD20160120)supported this research
文摘Anchiornis huxleyi, which is a member of the Middle-Late Jurassic Yanliao Biota, is the smallest feathered dinosaur ever known. It has been described as a critical link between feathered dinosaurs and birds. Recent studies, including those of Anchiornis, Xiaotingia, Eosinopteryx and Aurornis, challenged Archaeopteryx as the most basal bird. The new Anchiornis huxleyi specimens that are described in this paper show some minor different characters compared to previously reported Anchiornis specimens, which has revised the character list of Anchiornis and indicates a different phylogenetic point from former opinions.
文摘Exposures of strata spanning the Jurassic–Cretaceous boundary occur within several basins in western Liaoning and adjacent Inner Mongolia.These continental successions host world-renowned plant and animal fossils including feathered dinosaurs and the oldest flowering plant,Archaeofructus.The first feathered dinosaurs from northeastern China where found about 20 years ago and created a major impact in science and the media.Since then,many new specimens have been discovered.
文摘In present,there are increasing interests in the research on mechanical and control system of underwater vehicles.These ongoing research efforts are motivated by more pervasive applications of such vehicles including seabed oil and gas explorations, scientific deep ocean surveys,military purposes,ecological and water environmental studies,and also entertainments. However,the performance of underwater vehicles with screw type propellers is not prospective in terms of its efficiency and maneuverability.The main weaknesses of this kind of propellers are the production of vortices and sudden generation of thrust forces which make the control of the position and motion difficult. On the other hand,fishes and other aquatic animals are efficient swimmers,posses high maneuverability,are able to follow trajectories,can efficiently stabilize themselves in currents and surges,create less wakes than currently used underwater vehicle, and also have a noiseless propulsion.The fish's locomotion mechanism is mainly controlled by its caudal fin and paired pectoral fins.They are classified into Body and/or Caudal Fin(BCF)and Median and/or paired Pectoral Fins(MPF).The study of highly efficient swimming mechanisms of fish can inspire a better underwater vehicles thruster design and its mechanism. There are few studies on underwater vehicles or fish robots using paired pectoral fins as thruster.The work presented in this paper represents a contribution in this area covering study,design and implementation of locomotion mechanisms of paired pectoral fins in a fish robot.The performance and viability of the biomimetic method for underwater vehicles are highlighted through in-water experiment of a robotic fish.
文摘A novel Al-14.1 Mg-0.47 Si-0.31 Sc-0.17 Zr alloy was applied in the printing process of selective laser melting(SLM),and the corresponding microstructural feature,phase identification,tensile properties and corrosion behavior of the Al Mg Si Sc Zr alloy were studied in detail.As fabricated at 160 W and 200 mm/s,the Mg content of bulk sample decreased to 11.7 wt%due to the element vaporization at high energy density,and the density of this additively manufactured Al Mg Si Sc Zr alloy was 2.538 g/cm^(3),which is4.2%8.5%lighter than that of other SLM-processed Al alloys.After heat-treated(HT)at 325℃and 6 h,the microstructure was almost unchanged with an alternate distribution of fine equiaxed crystals and coarse columnar crystals.Nano-sized Al3(Sc,Zr)and Mg_(2)Si phases precipitated dispersedly in the Al matrix,and the tensile strength increased from 487.6 MPa to 578.4 MPa for precipitation strengthening and fine grain strengthening.With a fine grain size of 2.53μm,an excellent corrosion resistance was obtained for the as-printed(AP)Al Mg Si Sc Zr alloy.While the corrosion resistance of HT sample decreased slightly for the formation of non-dense oxide layer and pitting corrosion induced by diffuse precipitation distribution.This SLM-printed Al Mg Si Sc Zr alloy with high specific strength,good thermal stability and excellent corrosion resistance has broad prospects for the aerospace and automotive applications.
文摘Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To reveal the flying abilities, avian geometry of a golden eagle was extracted based on noncontact surface measurements using a ROMBER three-dimensional laser scanner. Distributions of a camber line, thickness and a secondary feather line of the extracted point cloud were fitted using convenient analytical expressions. A traditional airfoil was established with the camber line and thickness, then a combined airfoil was constructed by combining the traditional airfoil with a secondary feather. Oscillations of an airfoil as well as rapid pitch up were simplified as a sine wave around the quarter chord axis. Thereafter, both steady and unsteady aerodynamic performances of the airfoil are computed, the influences of the secondary feather on the steady and unsteady aerodynamics were further studied.
