Influence of Transverse Normal Pressure on Deformation Behavior of Sheet Metal

To investigate the influence of magnitude and distribution of the transverse normal pressure on deformation behavior of sheet metal,viscous pressure bulge test (VPB) of overlapping sheet metals is proposed,where the overlapped sheet metal is deformed under the dual-sided normal pressure provided by viscous medium and the overlapping sheet.The transverse normal pressure loading features provided by overlapping sheet metals are first simulated by DEFORM-2D.It shows that the magnitude and space distribution of transverse normal pressure are dependent on strain hardening exponent n-,strength coefficient K-and thickness t-values of the overlapping sheet metal.Based on the stress,deviator stress and strain distribution resulted from the finite element simulation,it indicated that the uniform transverse normal pressure has no effect on deviator stress,the figure and strain distribution of bulge specimens have no change.The non-uniform transverse normal pressure can remarkably change the figure and metal flow of specimens,and the formability of sheet metal can be improved by controlling the transverse normal pressure distribution.

A phenomenological model for plastic flow behavior of rotating band material with a large temperature range

The plastic flow behavior of the rotating band material is investigated in this paper. The rotating band material is processed from H96 brass alloy, which is hardened to a much higher yield strength compared to the annealed one. The dynamically uniaxial compression behavior of the material is tested using the split Hopkinson pressure bar(SHPB) with temperature and strain rate ranging from 297 to 1073 K and500 to 3000 s^(-1), respectively, and a phenomenological plastic flow stress model is developed to describe the mechanical behavior of the material. The material is found to present noticeable temperature sensitivity and weak strain-rate sensitivity. The construction of the plastic flow stress model has two steps. Firstly, three univariate stress functions, taking plastic strain, plastic strain rate and temperature as independent variable, respectively, are proposed by fixing the other two variables. Then, as the three univariate functions describe the special cases of flow stress behavior under various conditions, the principle of stress compatibility is adopted to obtain the complete flow stress function. The numerical results show that the proposed plastic flow stress model is more suitable for the rotating band material than the existing well-known models.

Behavioral plasticity is not significantly associated with head volume in a wild Chestnut Thrush(Turdus rubrocanus) population

Background: The drivers of intraspecific variation in behavioral plasticity are poorly known. A widely held hypothesis is that brain size is positively correlated with behavioral plasticity.Methods: A total of 71 Chestnut Thrushes(Turdus rubrocanus) were caught in the wild population. We quantified behavior plasticity of activity of individuals measured in the same cage across two contexts(common and with a novel object stimulation), using a random regression analysis. We then investigated whether head volume(a proxy for brain size) was associated with behavioral plasticity in activity level using Spearman rank-order correlation.Results: We found no significant evidence that activity plasticity was associated with relative head volume. There was no sex difference in head volume or in variance in head volume.Conclusions: We speculate that the absence of an association between brain volume and activity behavior plasticity may result from the inaccuracy of using external skull measurements to estimate brain size, or from a particular part of the brain being responsible for plasticity in activity level.

Plastic deformation behavior of ZK60 magnesium alloy with addition of neodymium

The hot deformation simulation of a ZK60 magnesiuln alloy at different temperatures from 373 to 673 K and different strain rates of 0.1, 0.01 and 0.002 s^-1 was studied by using the Gleebe-1500 simulator. The plastic deformation behavior was measured and the deformation activation energy was calculated. The microstructures of ZK60 magnesium alloy with an addition of neodymium during the deformation process were observed by using Polyvar-MET optical microscope and Tecnai G^2 20 TEM. The results show that the working hardening, the dynamic recovery and the dynamic recrystallization occur during the plastic deformation process at different temperatures and strain rates. The dynamic recrystallization starts when the temperature is over 473 K and the DRX grain size after hot deformation is only 5-10 μm. So the refined grains improve both the tensile strength and the elongation of alloys at room temperature. Neodymium is added into the alloy and a precipitate phase Mg12Nd that impedes the movement of dislocations is formed, which benefits to increasing mechanical properties of ZK60 magnesium alloy.

Effects of ultrasonic vibration on performance and microstructure of AZ31 magnesium alloy under tensile deformation

Ultrasonic vibration can reduce the forming force, decrease the friction in the metal forming process and improve the surface quality of the workpiece effectively. Tensile tests of AZ31 magnesium alloy were carried out. The stress–strain relationship, fracture modes of tensile specimens, microstructure and microhardness under different vibration conditions were analyzed, in order to study the effects of the ultrasonic vibration on microstructure and performance of AZ31 magnesium alloy under tensile deformation. The results showed that the different reductions of the true stress appeared under various ultrasonic vibration conditions, and the maximum decreasing range was 4.76%. The maximum microhardness difference among the 3 nodes selected along the specimen was HV 10.9. The fracture modes, plasticity and microstructure of AZ31 magnesium alloy also were affected by amplitude and action time of the ultrasonic vibration. The softening effect and the hardening effect occurred simultaneously when the ultrasonic vibration was applied. When the ultrasonic amplitude was 4.6 μm with short action time, the plastic deformation was dominated by twins and the softening effect was dominant. However, the twinning could be inhibited and the hardening effect became dominant in the case of high ultrasonic energy.

Vinous-throated parrotbills breed in invasive smooth cordgrass habitat:Can native birds avoid the potential ecological trap?

Native animals are facing long-term coexistence with invasive plants worldwide,the impacts of which on animal behavior remain poorly known.Potential ecological traps could threaten native birds breeding in invasive plant habitats,but behavioral strategies for birds to avoid such risks are few concerned.The invasion of Smooth Cordgrass(Spartina alterniflra) has seriously varied the vegetation landscape in the coastal wetlands of eastern China,and affected the habitat selection of native birds.Here,we investigated the nesting and breeding characteristics of a common native passerine,the Vinous-throated Parrotbill(Sinosuthora webbiana),in habitats dominated by native Common Reed(Phragmites australis) and exotic cordgrass.We found that parrotbills could complete their breeding cycle in cordgrass habitat.Most nest failure was attributed to predation in native habitat but tide inundation in cordgrass habitat.However,the nest success rate and daily survival rate(DSR) in cordgrass habitat were higher.Moreover,nest height was markedly higher in cordgrass habitat and was the most important influencing variable(positively correlated with the DSR).These results suggest that cordgrass habitat is a potential ecological trap due to the tide inundation,but some parrotbills seem to effectively avoid this risk by increasing nest height.Our study reveals that a native passerine changes its nesting behavior to accommodate invasive plant habitat and highlights that habitat changes caused by invasive plants may drive the adaptive evolution of native animal behavior.The limitation of these results must be acknowledged for the small sample size,and there is a need for a larger sample and long-term data for further verification.

PLASTIC BEHAVIOR AND CONSTITUTIVE MODELING OF ARMOR STEEL OVER WIDE TEMPERATURE AND STRAIN RATE RANGES

Plastic behavior of 603 armor steel is studied at strain rates ranging from 0.001 s-1 to 4500 s-1, and temperature from 288 K to 873 K. Emphasis is placed on the effects of temperature, strain rate, and plastic strain on flow stress. Based on experimental results, the JC and the KHL models are used to simulate flow stress of this material. By comparing the model prediction and the experimental results of strain rate jump tests, the KHL model is shown to have a better prediction of plastic behavior under complex loading conditions for this material, especially in the dynamic region.

How behavioral plasticity enables foraging under changing environmental conditions in the social wasp Vespula germanica (Hymenoptera: Vespidae)

The foraging strategy at abundant resources of the social wasp Vespula germanica includes scanning in the direction of the nest while memorizing resource-specific landmarks and contextual cues.In the present study,we sought to explore wasps'behavioral plasticity on foraging trips to resources whose location and composition changed after a single visit.We evaluated how contextual modifications of food displacement and replacements 60 cm apart from the original site,affect re-orientation for re-finding previously memorized food resources.The results showed that wasps detected and collected the resource faster when more changes were introduced on the following visit.If returning foragers discovered several modifications on both the location and the kind of resource,they collected food more rapidly from the displaced dish,than if only a single parameter in the environment had been changed.These findings illustrate the grade of behavioral plasticity in V.germanica while foraging on abundant resources,which may contribute to the understanding of the prodigious invasive success of this species in anthropized environments.

Behavioral plasticity, behavioral syndromes and animal personality in crustacean decapods： An imperfect map is better than no map

Despite their key role as model organisms in many behavioral studies, crustacean decapods have been only slightly touched upon by the recent surge of scientific interest in animal personality. Only seven articles investigated the issue in a handful of species among hermit crabs, crabs, and crayfish. Obviously, a limited number of publications does not mean that personality is rare in decapods. On the contrary, few studies might be the result of a form of reluctance by behavioral ecologists to deal with such a phenomenon in these and other invertebrates. This reluctance contrasts with the enthusiasm shown in tackling the beha- vioral plasticity issue. Here we discuss the possible theoretical and methodological difficulties raised by applying the animal per-sonality perspective to decapods and analyze implications of personality studies for their ecology, conservation, and welfare. By highlighting gaps in knowledge and directions of future research, our intention is to increase scientific emphasis on the issue.

As clear as mud： Turbidity induces behavioral changes in the African cichlid Pseudocrenilabrus multicolor

Aquatic biodiversity is being lost at an unprecedented rate. One factor driving this loss is increased turbidity, an en- vironmental stressor that can impose behavioral, morphological, and/or physiological costs on fishes. Here we describe the be- havioral response of a widespread African cichlid, Pseudocrenilabrus multicolor victoriae, to turbidity. We used a split-brood rearing design to test if F1 offspring reared in turbid water, originating from river （turbid） and swamp （clear） populations, behave differently than full-sibs reared in clear water. We examined two facets of behavior： （1） behaviors of fish in full sib groups, in- eluding activity level and social dynamics collected during the rearing period; and （2） male aggressive behavior directed at poten- tial male competitors after fish had reached maturity; this was done in an experimental set-up independent of the rearing aquaria. Regardless of population of origin, fish reared in turbid water were marginally less active and performed fewer social behaviors than those reared in clear water. On the other hand, when tested against a competitor in turbid water, males performed more ag- gressive behaviors, regardless of population of origin or rearing environment, Our results suggest a plastic behavioral response to turbidity that may allow P. multicolor to persist over a range of turbidity levels in nature by decreasing activity and general social behaviors and intensifying reproductive behaviors to ensure reproductive success [Current Zoology 58 （1）： 146-157, 2012].

Living on the edge: morphological and behavioral adaptations to a marginal high-elevation habitat in an arboreal mammal

Habitats are characterized by different local environmental conditions that influence both behavior and morphology of species,which can result in habitat-dependent phenotypic differences among animals living in heterogeneous environments.We studied 3 alpine populations of Eurasian red squirrels(Sciurus vulgaris),1 living in a marginal high-elevation habitat at the edge of the species’altitudinal distribution,and 2 occurring in higher-quality habitats.Here,we investigated whether squirrels living in the marginal area differed in 2 morphological parameters(body size and body mass)and/or in the expression of 4 personality traits estimated with an openfield test and a mirror image stimulation test(activity,exploration,activity-exploration,and social tendency).Furthermore,we tested whether within-individual variance of the traits(behavioral plasticity)was higher in the edge habitat.Male squirrels in the edge habitat were smaller and weighed less than in the other study areas,while among females,size–habitat relationships were less marked.These sex-specific patterns were explained by a strong association between body mass and reproductive success in female squirrels.Squirrels in the marginal habitat were more active,explorative,and had a more social personality than in the other habitats.However,in contrast to our predictions,behavioral plasticity was smaller in the marginal habitat,but only for the trait exploration.Our results suggest that animals choose the habitat that bestfits their personality,and that habitat-related differences in selective pressures may shape animals’morphology.

Design,challenges,and the potential of transcriptomics to understand social behavior

Rapid advances in Ribonucleic Acid sequencing(or RNA-seq)technology for analyzing entire transcriptomes of desired tissue samples,or even of single cells at scale,have revolutionized biology in the past decade.Increasing accessibility and falling costs are making it possible to address many problems in biology that were once considered intractable,including the study of various social behaviors.RNA-seq is opening new avenues to understand long-standing questions on the molecular basis of behavioral plasticity and individual variation in the expression of a behavior.As whole transcriptomes are examined,it has become possible to make unbiased discoveries of underlying mechanisms with little or no necessity to predict genes involved in advance.However,researchers need to be aware of technical limitations and have to make specific decisions when applying RNA-seq to study social behavior.Here,we provide a perspective on the applications of RNA-seq and experimental design considerations for behavioral scientists who are unfamiliar with the technology but are considering using it in their research.

Plasticity in the antipredator behavior of the orange-footed sea cucumber under shifting hydrodynamic forces

Marine invertebrates that move too slowly to evade unfavorable environmental change may instead exhibit phenotypic plasticity,allowing them to adjust to varying conditions.The orange-footed sea cucumber Cucumaria frondosa is a slow-moving suspension feeder that is preyed on by the purple sunstar Solaster endeca.The sea cucumber's antipredator behavior involves changing shape and detaching from the substratum,which might increase its probability of being displaced by water motion into an unsuitable environment.We hypothesized that sea cucumbers'antipredator responses would be diminished under stronger hydrodynamic forces,and that behavioral strategies would be flexible so that individuals could adjust to frequent changes in water flows.In a natural orange-footed sea cucumber habitat,individuals lived along a pronounced hydrodynamic gradient,allowing us to measure antipredator behavior under different water flow strengths.We placed purple sunstars in physical contact with sea cucumbers living at various points along the gradient to elicit antipredator responses.We then repeated this procedure in a laboratory mesocosm that generated weak and strong hydrodynamic forces similar to those observed at the field site.Subjects in the mesocosm experiment were tested in both wave conditions to determine if their antipredator behavior would change in response to sudden environmental change,as would be experienced under deteriorating sea conditions.Antipredator responses did not covary with hydrodynamic forces in the field.However,antipredator responses in the mesocosm experiment increased when individuals were transplanted from strong to weak forces and decreased when transplanted from weak to strong forces.Overall,our results indicate environmentally induced plasticity in the antipredator behavior of the orange-footed sea cucumber.

Serration and Noise Behavior in Advanced Materials

The Chinese Materials Research Society（C-MRS）Conference（2015）was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4international symposia.As one of 4international symposia,＂Serration and noise behavior in advanced materials＂

Context-dependent responses of food-hoarding to competitors in Apodemus peninsulae:implications for coexistence among asymmetrical species

Superior species may have distinct advantages over subordinates within asymmetrical interactions among sympatric animals.However,exactly how the subordinate species coexists with superior species is unknown.In the forests west of Beijing City,intense asymmetrical interactions of food competition exist among granivorous rodents(e.g.Apodemus peninsulae,Niviventer confucianus,Sciurotamias davidianus and Tscherskia triton)that have broadly overlapping habitats and diets but have varied body size(range 15-300 g),hoarding habits(scatter vs larder)and/or daily rhythm(diurnal vs nocturnal).The smallest rodent,A.peninsulae,which typically faces high competitive pressure from larger rodents,is an ideal model to explore how subordinate species coexist with superior species.Under semi-natural enclosure conditions,we tested responses of seed-hoarding behavior in A.peninsulae to intraspecific and interspecific competitors in the situations of pre-competition(without competitor),competition(with competitor)and post-competition(competitor removed).The results showed that for A.peninsulae,the intensity of larder-hoarding increased and the intensity of scatter-hoarding declined in the presence of intraspecifics and S.davidianus,whereas A.peninsulae ceased foraging and hoarding in the presence of N.confucianus and T.triton.A.peninsulae reduced intensity of hoarding outside the nest and moved more seeds into the nest for larder-hoarding under competition from intraspecific individuals and S.davidianus.In most cases,the experimental animals could recover to their original state of pre-competition when competitors were removed.These results suggest that subordinate species contextually regulate their food-hoarding strategies according to different competitors,promoting species coexistence among sympatric animals that have asymmetrical food competition.

Hot workability of Mg-9Y-1MM-0.6Zr alloy

The behavior evolvement of Mg-9Y-1MM-0.6Zr （WE91） alloy during hot deformation process was discussed. The flow stress behavior of magnesium alloy over the strain rate range of 0.001 to 1 s–1 and the temperature range of 653 to 773 K was studied on a Gleeble-1500D hot simulator under the maximum deformation degree of 60%. The experimental results showed that the relationship between stress and strain was obviously affected by the strain rate and deformation temperature and the flow curves observed were typical of the occurrence of dynamic recrystallization. The flow stress of WE91 magnesium alloy during high temperature deformation could be represented by the Zener-Hollomon parameter in the hyperbolic Arrhenius-type equation. The average deformation activation energy Q and strain coefficient n were 224.11 kJ/mol and 3.08 by calculation,respectively. The processing maps were calculated and analyzed according to the dynamic materials model. The map at strain of 0.916 exhibited three domains with peak efficiency of 49%,44% and 42%,respectively. It was found that the alloy could be extruded at 693 K with mechanical properties of σ0.2=240 MPa,σb=315 MPa and δ=15.5%.

Flexible foraging decisions made by workers of the social wasp Vespula germanica (Hymenoptera: Vespidae) in response to different resources: influence of ontogenetic shifts and colony feedback

Decisions made by foraging animals conform a complex process based on the integration of information from multiple external environmental stimuli and internal physiological signals,which in turn are modulated by individual experience and a detection threshold of each individual.For social insects in which foraging is limited to given age subcastes,individual foraging decisions may also be affected by ontogenetic shifts and colony requirements.We studied the short-term changes in foraging preferences of the generalist wasp Vespula germanica,focusing on whether the individual response to different resources could be influenced by the ontogenetic shifts and/or by social interaction with nestmates.We carried both laboratory and field experiments to confront worker wasps to a short-term resource switch between either protein or carbohydrate-based foods.We tested the response of(1)Preforager workers(no foraging experience nor interaction with other wasps),(2)Forager workers(experience in foraging and no colony feedback),and(3)Wild forager workers(foraging naturally and exposed to free interactions with nestmates).We evaluated the maxilla-labium extension response(MaLER)for laboratory assays or the landing response for field assays.We observed that for wasps deprived of colony feedback(either preforagers or foragers),the protein-rich foods acceptance threshold increased(and thus a lower level of foraging on that item was observed)if they had foraged on carbohydrates previously,whereas carbohydrates were accepted in all assays.However,wasps immersed in a natural foraging context did accept protein foods regardless of their first foraging experience and reduced the carbohydrates collected when trained on protein foods.We provide evidence that short-term changes in foraging preferences depend on the type of resource foraged and on the social interactions,but not on ontogenetic shifts.

What is going on in magnesium alloys？

China has been developed into one of the most active regions in terms of both fundamental and applied research on magnesium （Mg） and its alloys in the world from a solid base laid by its prominent metallurgist and materials scientists over the past decades. Nowadays, a large number of young-generation researchers have been inspired by their predecessors and become the key participants in the fields of Mg alloys, which consequently led to the establishment of China Youth Scholar Society for Magnesium Alloys Research in 2015. Since then, the first two China Youth Scholars Symposiums on Mg Alloys Research had been held at Harbin （2015） and Chongqing （2016） China, respectively. A number of crucial research inter- ests related to fundamental and applied Mg research were discussed at the conferences and summarized in this short perspective, aiming to boost far-reaching initiatives for development of new Mg-based materials to satisfy the requirements for a broad range of industrial employments. Herein, four main aspects are included as follows： i） Plastic deformation mechanism and strengthening strategy, ii） Design and development of new Mg-based materials, iii） Key service properties, and iv） New processing technologies.

Feeding mediated web-building plasticity in a cobweb spider

Behavioral plasticity has been proposed as a means by which animals alter their phenotypes in response to changing conditions.Animals may display behavioral plasticity as a consequence of environmental variation.The detritus-based,bell-shaped cobweb spider Campanicola campanulata is an ideal model to study behavioral plasticity,because its web architecture is easy to be quantified,and the functions of different parts of the web are clear.Though the plasticity of cobweb architecture has been reported in a few species,retreats as impor-tant defensive structures have rarely been considered before because retreats in most cobwebs are relatively small compared with the web size.We studied the web-building behaviors of C.campanulata under different feeding regimes.We set up 3 spider treatments with different feeding conditions:marginally well fed,moderately well fed,and extremely well fed,and observed the differences in the web architecture among them.In addition,we measured the mechanical properties of anchor silk,and also calculated the foraging and defense investment of the spiders.The results showed that marginally well-fed spiders build cobwebs with significantly longer length of anchor silk,lower retreat to the ground,more number and longer gumfooted lines,and larger capture area,while extremely well-fed spiders build cobwebs with significantly bigger retreat volume and higher height of retreat to the ground.In addition,marginally well-fed spiders invest significantly less during cobweb construction.However,there was no significant difference between the breaking force and elongation at break in anchor silk among different treatments.These results demonstrated that marginally well-fed spiders invest more in foraging,and extremely well-fed spiders invest more in defense,and the spider made a balance between foraging and predator avoidance in response to changes in physiological state.Our study strengthens the current understanding of web construction in cobweb spiders,especially those facing high costs during retreat construction.

Phenotype manipulation influences microhabitat choice in pygmy grasshoppers

The matching habitat choice hypothesis posits that individuals actively choose those microhabitats that best match their specific phenotype to maximize fitness. Despite the profound implications, matching habitat choice has not been unequivo- cally demonstrated. We conducted two experiments to examine the impact of pigmentation pattern in the color polymorphic pygmy grasshopper Tetrix subulata on habitat choice in a laboratory thermal mosaic arena. We found no behavioral differences in the thermal mosaic among pygmy grasshoppers belonging to either pale, intermediate or dark natural color morphs. However, af- ter manipulating the grasshoppers＇ phenotype, the utilization through time of warmer and colder parts of the arena was different for black-painted and white-painted individuals. White-painted individuals used warmer parts of the arena, at least during the ini- tial stage of the experiment. We conclude that microhabitat choice represents a form of behavioural plasticity. Thus, even if the choice itself is flexible and not genetically determined, it can still lead to spatial genetic structure in the population because the phenotypes themselves may be genetically mediated [Current Zoology 58 （3）： 392--400, 2012].