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Sample records for behavioral caste differentiation

  1. Size-dependent foraging gene expression and behavioral caste differentiation in Bombus ignitus

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    Yokoyama Jun

    2009-09-01

    Full Text Available Abstract Background In eusocial hymenopteran insects, foraging genes, members of the cGMP-dependent protein kinase family, are considered to contribute to division of labor through behavioral caste differentiation. However, the relationship between foraging gene expression and behavioral caste in honeybees is opposite to that observed in ants and wasps. In the previously examined eusocial Hymenoptera, workers behave as foragers or nurses depending on age. We reasoned that examination of a different system of behavioral caste determination might provide new insights into the relationship between foraging genes and division of labor, and accordingly focused on bumblebees, which exhibit size-dependent behavioral caste differentiation. We characterized a foraging gene (Bifor in bumblebees (Bombus ignitus and examined the relationship between Bifor expression and size-dependent behavioral caste differentiation. Findings A putative open reading frame of the Bifor gene was 2004 bp in length. It encoded 668 aa residues and showed high identity to orthologous genes in other hymenopterans (85.3-99.0%. As in ants and wasps, Bifor expression levels were higher in nurses than in foragers. Bifor expression was negatively correlated with individual body size even within the same behavioral castes (regression coefficient = -0.376, P P = 0.018, within foragers. Conclusion These findings indicate that Bifor expression is size dependent and support the idea that Bifor expression levels are related to behavioral caste differentiation in B. ignitus. Thus, the relationship between foraging gene expression and behavioral caste differentiation found in ants and wasps was identified in a different system of labor determination.

  2. Hot Deformation Behavior of a Differential Pressure Casting Mg-8Gd-4Y-Nd-Zr Alloy

    Science.gov (United States)

    Tang, Changping; Liu, Wenhui; Chen, Yuqiang; Liu, Xiao; Deng, Yunlai

    2017-01-01

    To fabricate components with high performance, the compression behavior and microstructure evolution of a differential pressure casting Mg-8Gd-4Y-Nd-Zr alloy were investigated. The cylindrical samples were compressed at temperatures ranging from 350 °C to 525 °C and strain rates ranging from 0.001 s-1 to 2 s-1. For the compression at 350 °C, dynamic precipitation occurs and consumes much of the solutes in the matrix, which should be avoided. The recrystallized grain size (d) decreases when the proposed deformation parameter (Z) increases, and the resulting Z-d relationship is established. Finally, a superior deformation process of 500 °C/0.01 s-1 is determined based on the experimental results. Moreover, a plate with an ultimate tensile strength of 413 MPa was fabricated.

  3. Hot Deformation Behavior of a Differential Pressure Casting Mg-8Gd-4Y-Nd-Zr Alloy

    Science.gov (United States)

    Tang, Changping; Liu, Wenhui; Chen, Yuqiang; Liu, Xiao; Deng, Yunlai

    2016-11-01

    To fabricate components with high performance, the compression behavior and microstructure evolution of a differential pressure casting Mg-8Gd-4Y-Nd-Zr alloy were investigated. The cylindrical samples were compressed at temperatures ranging from 350 °C to 525 °C and strain rates ranging from 0.001 s-1 to 2 s-1. For the compression at 350 °C, dynamic precipitation occurs and consumes much of the solutes in the matrix, which should be avoided. The recrystallized grain size (d) decreases when the proposed deformation parameter (Z) increases, and the resulting Z-d relationship is established. Finally, a superior deformation process of 500 °C/0.01 s-1 is determined based on the experimental results. Moreover, a plate with an ultimate tensile strength of 413 MPa was fabricated.

  4. Casting behavior of titanium alloys in a centrifugal casting machine.

    Science.gov (United States)

    Watanabe, K; Miyakawa, O; Takada, Y; Okuno, O; Okabe, T

    2003-05-01

    Since dental casting requires replication of complex shapes with great accuracy, this study examined how well some commercial titanium alloys and experimental titanium-copper alloys filled a mold cavity. The metals examined were three types of commercial dental titanium [commercially pure titanium (hereinafter noted as CP-Ti), Ti-6Al-4V (T64) and Ti-6Al-7Nb (T67)], and experimental titanium-copper alloys [3%, 5% and 10% Cu (mass %)]. The volume percentage filling the cavity was evaluated in castings prepared in a very thin perforated sheet pattern and cast in a centrifugal casting machine. The flow behavior of the molten metal was also examined using a so-called "tracer element technique." The amounts of CP-Ti and all the Ti-Cu alloys filling the cavity were similar; less T64 and T67 filled the cavity. However, the Ti-Cu alloys failed to reach the end of the cavities due to a lower fluidity compared to the other metals. A mold prepared with specially designed perforated sheets was effective at differentiating the flow behavior of the metals tested. The present technique also revealed that the more viscous Ti-Cu alloys with a wide freezing range failed to sequentially flow to the end of the cavity.

  5. Newly developed vacuum differential pressure casting of thin-walled complicated Al-alloy castings

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The newly designed vacuum differential pressure casting (VDPC) unit was introduced, by which the capability of the VDPC process to produce thin-walled complicated Al-alloy castings, that are free from oxides, gas pore and shrinkage cavity and thus enhance overall part quality, was studied. Experimental results were compared with those of traditional gravity pouring and vacuum suction casting. The first series of experiments were focused on investigating the castability of thin section Al-alloy casting. In the second series of experiments the metallographic evidence, casting strength and soundness were examined. Finally, case studies of very interesting thin walled complicated casting applications were described. The advantages of the described technique have made possible to produce thin walled complicated Al-alloy casting (up to a section thickness of 1 mm), which is not practical for gravity pouring and vacuum suction casting.

  6. Simulation research on control algorithm of differential pressure casting process

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    Chai Yan; Jie Wanqi; Yang Bo

    2009-01-01

    To improve the precision of the filling pressure curve of differential pressure casting controlled with PID controller,the model of differential pressure casting process is established and two pressure-difference control systems using PID algorithm and Dahlin algorithm are separately designed in MATLAB. The scheduled pressure curves controlled with PID algorithm and Dahlin algorithm,respectively,are comparatively simulated in MATLAB.The simulated pressure curves obtained show that the control precision with Dahlin algorithm is higher than that with PID algorithm in the differential pressure casting process,and it was further verified by production practice.

  7. Mechanisms regulating caste differentiation in an aphid social system.

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    Shibao, Harunobu; Kutsukake, Mayako; Matsuyama, Shigeru; Fukatsu, Takema; Shimada, Masakazu

    2010-01-01

    For evolution and maintenance of the social systems of insect colonies, caste production should be controlled in response to external cues so that caste ratio in the colony is kept at an optimal range. Recent developments using artificial diet rearing techniques have revealed an underlying mechanism for adaptive control of caste production in a social aphid, Tuberaphis styraci, which has a sterile soldier caste in the 2(nd) instar. Aphid density was the proximate cue that acts on 1(st) instar nymphs and embryos to induce soldier differentiation. The final determination of soldier differentiation occurred postnatally, probably at a late 1(st) instar stage. Direct contact stimuli from live non-soldier aphids mediated the density effect. While coexisting non-soldiers facilitated soldier differentiation in 1(st) instar nymphs, coexisting soldiers acted to suppress such differentiation. These results suggest that caste production in aphid colonies is controlled by positive and negative feedback mechanisms consisting of density-dependent induction and suppression of soldier differentiation. Here, we demonstrate the mechanisms that coordinate aphid society, and provide a striking case of clonal superorganism system where simple responses of colony members to local extrinsic stimuli are integrated into a highly organized regulation of the whole colony.

  8. Soldier caste influences on candidate primer pheromone levels and juvenile hormone-dependent caste differentiation in workers of the termite Reticulitermes flavipes

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    Caste systems and the division of labor they make possible are common underlying features of all social insects. Multiple extrinsic factors have been shown to impact caste differentiation; for example, primer pheromones are chemical signaling molecules produced by certain castes that impact developm...

  9. Characterization of head transcriptome and analysis of gene expression involved in caste differentiation and aggression in Odontotermes formosanus (Shiraki.

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    Qiuying Huang

    Full Text Available BACKGROUND: The subterranean termite Odontotermes formosanus (Shiraki is a serious insect pest of trees and dams in China. To date, very little is known about genomic or transcriptomic data for caste differentiation and aggression in O. formosanus. Hence, studies on transcriptome and gene expression profiling are helpful to better understand molecular basis underlying caste differentiation and aggressive behavior in O. formosanus. METHODOLOGY AND PRINCIPAL FINDINGS: Using the Illumina sequencing, we obtained more than 57 million sequencing reads derived from the heads of O. formosanus. These reads were assembled into 116,885 unique sequences (mean size  =  536 bp. Of the unigenes, 30,646 (26.22% had significant similarity with proteins in the NCBI nonredundant protein database and Swiss-Prot database (E-value<10(-5. Of these annotated unigenes, 10,409 and 9,009 unigenes were assigned to gene ontology categories and clusters of orthologous groups, respectively. In total, 19,611 (25.52% unigenes were mapped onto 242 pathways using the Kyoto Encyclopedia of Genes and Genomes Pathway database (KEGG. A total of 11,661 simple sequence repeats (SSRs were predicted from the current transcriptome database. Moreover, we detected seven putative genes involved in caste differentiation and six putative genes involved in aggression. The qPCR analysis showed that there were significant differences in the expression levels of the three putative genes hexamerin 2, β-glycosidase and bicaudal D involved in caste differentiation and one putative gene Cyp6a20 involved in aggression among workers, soldiers and larvae of O. formosanus. CONCLUSIONS: To our knowledge, this is the first study to characterize the complete head transcriptome of a higher fungus-cultivating termite using high-throughput sequencing. Our study has provided the comprehensive sequence resources available for elucidating molecular basis underlying caste differentiation and aggressive

  10. Volume Ray Casting with Peak Finding and Differential Sampling

    KAUST Repository

    Knoll, A.

    2009-11-01

    Direct volume rendering and isosurfacing are ubiquitous rendering techniques in scientific visualization, commonly employed in imaging 3D data from simulation and scan sources. Conventionally, these methods have been treated as separate modalities, necessitating different sampling strategies and rendering algorithms. In reality, an isosurface is a special case of a transfer function, namely a Dirac impulse at a given isovalue. However, artifact-free rendering of discrete isosurfaces in a volume rendering framework is an elusive goal, requiring either infinite sampling or smoothing of the transfer function. While preintegration approaches solve the most obvious deficiencies in handling sharp transfer functions, artifacts can still result, limiting classification. In this paper, we introduce a method for rendering such features by explicitly solving for isovalues within the volume rendering integral. In addition, we present a sampling strategy inspired by ray differentials that automatically matches the frequency of the image plane, resulting in fewer artifacts near the eye and better overall performance. These techniques exhibit clear advantages over standard uniform ray casting with and without preintegration, and allow for high-quality interactive volume rendering with sharp C0 transfer functions. © 2009 IEEE.

  11. Temperature affect on caste differentiation and protein composition in Coptotermes formosanus

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    Caste systems, and the division of labor they make possible, are common underlying features of all social insects. In termites, multiple extrinsic factors have been shown to impact caste differentiation; for example, temperature has been shown to increase soldier production. The objective of this in...

  12. An adaptive view of caste differentiation in the neotropical wasp Polybia (Trichothorax) sericea Olivier (Hymenoptera: Vespidae).

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    Desuó, I C; Souza-Galheico, C B; Shima, S N; Santos, G M M; Cruz, J D; Bichara Filho, C C; Dias, C T S

    2011-01-01

    The tribe Epiponini comprehends the swarm-founding Neotropical wasps, with several species endemic to Brazil, which are extremely important in studies of social evolution of wasps. The Epiponini diverge in several ways from the definitions of high eusociality, since caste syndromes range from species without morphological caste differentiation to those with complete caste dimorphism, and all species are polygynous. Frequently, indirect studies based on morphometry and physiology are the only solutions to collect data regarding the natural history and caste system in this tribe, since most species are extremely aggressive and build enveloped nests, usually in places of difficult access. We analyzed morphological parameters in seven colonies of the Epiponini species Polybia (Trichothorax) sericea Olivier in different phases of colonial development. Nine body variables were taken and females were classified according to their ovary development and spermathecal contents. The results showed that caste differences in this species are based on a contrast among variables: queens have larger mesosoma and abdomen, but are smaller in head width and wing length. These results suggest that morphological caste differentiation in this species is based mainly on body shape. We considered this combination of characters as being adaptive. We also showed that caste differences varied according to the colony cycle, with more conspicuous differences when queen number is reduced.

  13. Cast Iron And Mineral Cast Applied For Machine Tool Bed - Dynamic Behavior Analysis

    OpenAIRE

    2015-01-01

    Cast iron and mineral cast are the materials most often used in the machine structural elements design (bodies, housings, machine tools beds etc.). The materials significantly differ in physical and mechanical properties. The ability to suppress vibration is one of the most important factors determining the dynamic properties of the machine and has a significant impact on the machining capabilities of a machine tool. Recent research and development trends show that there is a clear tendency t...

  14. Squeeze casting of aluminum alloy A380: Microstructure and tensile behavior

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    Li Fang

    2015-09-01

    Full Text Available A380 alloy with a relatively thick cross-section of 25 mm was squeeze cast using a hydraulic press with an applied pressure of 90 MPa. Microstructure and tensile properties of the squeeze cast A380 were characterized and evaluated in comparison with the die cast counterpart. Results show that the squeeze cast A380 possesses a porosity level much lower than the die cast alloy, which is disclosed by both optical microscopy and the density measurement technique. The results of tensile testing indicate the improved tensile properties, specifically ultimate tensile strength (UTS: 215.9 MPa and elongation (Ef: 5.4%, for the squeeze cast samples over those of the conventional high-pressure die cast part (UTS: 173.7 MPa, Ef: 1.0%. The analysis of tensile behavior shows that the squeeze cast A380 exhibits a high tensile toughness (8.5 MJ·m-3 and resilience (179.3 kJ·m-3 compared with the die cast alloy (toughness: 1.4 MJ·m-3, resilience: 140.6 kJ·m-3, despite that, during the onset of plastic deformation, the strain-hardening rate of the die cast specimen is higher than that of the squeeze cast specimens. The microstructure analyzed by the scanning electron microscopy (SEM shows that both the squeeze and die cast specimens contain the primary α-Al, Al2Cu, Al5FeSi phase and the eutectic Si phase. But, the Al2Cu phase present in the squeeze cast alloy is relatively large in size and quantity. The SEM fractography evidently reveals the ductile fracture features of the squeeze cast A380 alloy.

  15. Regulation of caste differentiation in the honey bee (Apis mellifera L.)

    NARCIS (Netherlands)

    Goewie, E.A.

    1978-01-01

    The nutritional environment of honey-bee larvae affects the juvenile hormone (JH) titre of larval haemolymph and tissues. In this investigation the mechanism for the regulation of caste differentiation has been studied.Chemo- and mechanoreceptors are found on larval mouthparts. Chemoreceptors on max

  16. Electrochemical behavior of cast Ti-Ag alloys.

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    Takahashi, Masatoshi; Kikuchi, Masafumi; Takadai, Yukyo; Okabe, Toru; Okuno, Osamu

    2006-09-01

    Anodic polarization tests were performed in 0.9% NaCl and 1% lactic acid solutions to characterize the relationship between the corrosion behavior and the microstructures of cast Ti-Ag (5-40% Ag) alloys. The anodic polarization curves for the Ti-Ag alloys up to 17.5% Ag were similar to those for pure titanium in both solutions. On the other hand, an abrupt increase in the current density was observed for the alloys with more than 20% Ag in the NaCl solution and with more than 27.5% Ag in the lactic acid solution. The microstructures of the corroded alloy surfaces indicated the deterioration of precipitated intermetallic compounds along the grain boundaries. The Ti-Ag alloys up to 17.5% Ag had excellent corrosion resistance similar to that of pure titanium. The alloys with 20-25% Ag may be also used as dental alloys, since they passivated again immediately after preferential dissolution in the NaCl solution.

  17. Thermomechanical Behavior in Continuous Bloom Casting with Different Mold Tapers

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    LUO Xin; CHEN Yong; SHEN Houfa

    2008-01-01

    A two-dimensional finite element model was used to analyze the thermal and mechanical behavior dunng solidification of the strand in a continuous bloom casting mold.The coupled heat transfer and defermation were analyzed to simulate the formation of the air gap between the mold and the strand.The model was used to investigate the influence of mold taper on the temperature and stress distributions in the strand.The results show that the air gap mainly forms around the strand corner,causing a hoRer and thinner solidifying shell in this region.The mold taper partially compensates for the strand shell shnnkage and reduces the infiuence of the air gap on the heat transfer.The mold taper compresses the shell and changes the stress state around the stmnd comer region.As the strand moves down into the mold,the mold constraint causes compressive stress beneath the comer surface.which reduces the hot tear that forms on the strand.

  18. Effect of Strain Rate on Compression Behavior of Vinyl Ester Resin Casting

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    XIONG Tao; YANG Bin; XIONG Jie; XU Xian-jian; ZHOU Kai; MAO Ming-zhong

    2006-01-01

    Quasi-static and high strain rate compressive experiments on vinyl ester casting were carried out by means of MTS (Material Test System) and Hopkinson bar. The behaviors of the compressed unstable and fracture of the resin casting at different strain rates were investigated. The results indicate that the response behavior of the resin casting is controlled by different mechanisms at different strain rate, and some mechanical properties of vinyl ester casting are ratedependent: the casting are destroyed in toughness model under strain rate 3.3 × 10-4 ~ 6.6 × 10-3/s, while the casting are destroyed in brittleness model under strain rate 950~5800/s. The yield stress, yield strain energy density are all increased with the increasing strain rates at quasi-static as well as at high strain rates. What is interesting is that the yield strain decreased with the strain rates increasing at quasi-static while increased at high strain rates. It is considered that the casting occurred forcing high elastic deformation at high strain rates. The damage of the specimens is mainly controlled by axial stress before unstable deformation, while mainly controlled by shear stress after unstable deformation, and then developed to fracture finally. This progress is rate-dependent: the development of the cracks inside the castings increased with the strain rate increasing.

  19. Population differentiation of southern Indian male lineages correlates with agricultural expansions predating the caste system.

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    Arunkumar, Ganeshprasad; Soria-Hernanz, David F; Kavitha, Valampuri John; Arun, Varatharajan Santhakumari; Syama, Adhikarla; Ashokan, Kumaran Samy; Gandhirajan, Kavandanpatti Thangaraj; Vijayakumar, Koothapuli; Narayanan, Muthuswamy; Jayalakshmi, Mariakuttikan; Ziegle, Janet S; Royyuru, Ajay K; Parida, Laxmi; Wells, R Spencer; Renfrew, Colin; Schurr, Theodore G; Smith, Chris Tyler; Platt, Daniel E; Pitchappan, Ramasamy

    2012-01-01

    Previous studies that pooled Indian populations from a wide variety of geographical locations, have obtained contradictory conclusions about the processes of the establishment of the Varna caste system and its genetic impact on the origins and demographic histories of Indian populations. To further investigate these questions we took advantage that both Y chromosome and caste designation are paternally inherited, and genotyped 1,680 Y chromosomes representing 12 tribal and 19 non-tribal (caste) endogamous populations from the predominantly Dravidian-speaking Tamil Nadu state in the southernmost part of India. Tribes and castes were both characterized by an overwhelming proportion of putatively Indian autochthonous Y-chromosomal haplogroups (H-M69, F-M89, R1a1-M17, L1-M27, R2-M124, and C5-M356; 81% combined) with a shared genetic heritage dating back to the late Pleistocene (10-30 Kya), suggesting that more recent Holocene migrations from western Eurasia contributed caste) system from the historically-documented Brahmin migrations into the area. In contrast, the overall Y-chromosomal patterns, the time depth of population diversifications and the period of differentiation were best explained by the emergence of agricultural technology in South Asia. These results highlight the utility of detailed local genetic studies within India, without prior assumptions about the importance of Varna rank status for population grouping, to obtain new insights into the relative influences of past demographic events for the population structure of the whole of modern India.

  20. Study of Al/cast iron interface and graphite behavior

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    Akbarifar M.

    2017-01-01

    Full Text Available The interface characteristics of aluminum/cast iron bimetals produced by compound casting were investigated. Aluminum melt was poured into molds, at 700°C and 750°C, around cylindrical cast iron bars having melt-to-solid volume ratios (Vm/Vs of 3, 5 and 8, respectively. Microscopic observations showed that a reaction layer may form at the interface. This layer is composed of Fe2Al5 intermetallic which has been formed initially at the notches of the insert’s surface after making contact with the molten metal. The thickness of the interaction layer varied from 5μm, for the sample produced at 700°C and 3 Vm/Vs, up to 20μm for the sample poured at 750°C and 8 Vm/Vs. Microstructural analysis showed that increasing of the temperature and the melt-to-solid (m/s volume ratio leads to the formation of a thicker and more uniform intermetallic layer. Microhardness of the Fe2Al5 compound was measured 824 HV. A mechanism is suggested for the nucleation and growth of this intermetallic layer and also encapsulation of the flake graphite at the interface of two metals. It seems that the thermal and chemical situation at the interface of two metals, leads to an acceptable wettability of the graphite by molten aluminum.

  1. Influence of the casting processing route on the corrosion behavior of dental alloys.

    Science.gov (United States)

    Galo, Rodrigo; Rocha, Luis Augusto; Faria, Adriana Claudia; Silveira, Renata Rodrigues; Ribeiro, Ricardo Faria; de Mattos, Maria da Gloria Chiarello

    2014-12-01

    Casting in the presence of oxygen may result in an improvement of the corrosion performance of most alloys. However, the effect of corrosion on the casting without oxygen for dental materials remains unknown. The aim of this study was to investigate the influence of the casting technique and atmosphere (argon or oxygen) on the corrosion behavior response of six different dental casting alloys. The corrosion behavior was evaluated by electrochemical measurements performed in artificial saliva for the different alloys cast in two different conditions: arc melting in argon and oxygen-gas flame centrifugal casting. A slight decrease in open-circuit potential for most alloys was observed during immersion, meaning that the corrosion tendency of the materials increases due to the contact with the solution. Exceptions were the Co-based alloys prepared by plasma, and the Co-Cr-Mo and Ni-Cr-4Ti alloys processed by oxidized flame, in which an increase in potential was observed. The amount of metallic ions released into the artificial saliva solution during immersion was similar for all specimens. Considering the pitting potential, a parameter of high importance when considering the fluctuating conditions of the oral environment, Co-based alloys show the best performance in comparison with the Ni-based alloys, independent of the processing route.

  2. Population differentiation of southern Indian male lineages correlates with agricultural expansions predating the caste system.

    Directory of Open Access Journals (Sweden)

    Ganeshprasad Arunkumar

    Full Text Available Previous studies that pooled Indian populations from a wide variety of geographical locations, have obtained contradictory conclusions about the processes of the establishment of the Varna caste system and its genetic impact on the origins and demographic histories of Indian populations. To further investigate these questions we took advantage that both Y chromosome and caste designation are paternally inherited, and genotyped 1,680 Y chromosomes representing 12 tribal and 19 non-tribal (caste endogamous populations from the predominantly Dravidian-speaking Tamil Nadu state in the southernmost part of India. Tribes and castes were both characterized by an overwhelming proportion of putatively Indian autochthonous Y-chromosomal haplogroups (H-M69, F-M89, R1a1-M17, L1-M27, R2-M124, and C5-M356; 81% combined with a shared genetic heritage dating back to the late Pleistocene (10-30 Kya, suggesting that more recent Holocene migrations from western Eurasia contributed <20% of the male lineages. We found strong evidence for genetic structure, associated primarily with the current mode of subsistence. Coalescence analysis suggested that the social stratification was established 4-6 Kya and there was little admixture during the last 3 Kya, implying a minimal genetic impact of the Varna (caste system from the historically-documented Brahmin migrations into the area. In contrast, the overall Y-chromosomal patterns, the time depth of population diversifications and the period of differentiation were best explained by the emergence of agricultural technology in South Asia. These results highlight the utility of detailed local genetic studies within India, without prior assumptions about the importance of Varna rank status for population grouping, to obtain new insights into the relative influences of past demographic events for the population structure of the whole of modern India.

  3. Unnotched Charpy Impact Energy Transition Behavior of Austempered Engineering Grade Ductile Iron Castings

    Science.gov (United States)

    Kisakurek, Sukru Ergin; Ozel, Ahmet

    2014-04-01

    Unnotched Charpy impact energy transition behavior of five different engineering grade ductile iron castings, as specified by EN 1563 Standards, were examined in as-cast, as well as in austempered states. ADIs were produced with the maximum impact energy values permissible for the grades. Austempering treatment detrimented the sub-zero impact properties of the ferritic castings, but considerably enhanced those of the pearlitic-ferritic irons. The impact energy transition behavior of the austempered states of all the grades examined were noted to be determined by the progressive transformation of the unavoidable carbon-unsaturated and untransformed regions of the austenite remaining in the matrix of the austempered ductile iron to martensite with decreasing temperature.

  4. Electrochemical behavior of Co-Cr and Ni-Cr dental cast alloys

    Institute of Scientific and Technical Information of China (English)

    Viswanathan S. SAJI; Han-Cheol CHOE

    2009-01-01

    The cast structures influencing the electrochemical corrosion behavior of Co-Cr and Ni-Cr dental alloys were studied using potentiodynamic polarization and AC impedance in 0.9% (mass fraction) NaCl solution at (37±1) ℃. The phase and microstructure of the alloys that were fabricated using two different casting methods viz. centrifugal casting and high frequency induction casting, were examined using X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. The roles of alloying elements and the passive film homogeneity on the corrosion resistance of Co-Cr-Mo and Ni-Cr-Mo dental cast alloys were reviewed. The results of electrochemical study show that the dependence of corrosion resistance on the microstructure associated with the casting methods is marginal. The Co-Cr alloy exhibits more desirable corrosion resistance properties than the Ni-Cr alloy. There is severe preferential dissolution of Ni-rich, Cr and Mo depleted zones in the Ni-Cr alloy.

  5. Hox gene expression leads to differential hind leg development between honeybee castes.

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    Bomtorin, Ana Durvalina; Barchuk, Angel Roberto; Moda, Livia Maria; Simoes, Zila Luz Paulino

    2012-01-01

    Beyond the physiological and behavioural, differences in appendage morphology between the workers and queens of Apis mellifera are pre-eminent. The hind legs of workers, which are highly specialized pollinators, deserve special attention. The hind tibia of worker has an expanded bristle-free region used for carrying pollen and propolis, the corbicula. In queens this structure is absent. Although the morphological differences are well characterized, the genetic inputs driving the development of this alternative morphology remain unknown. Leg phenotype determination takes place between the fourth and fifth larval instar and herein we show that the morphogenesis is completed at brown-eyed pupa. Using results from the hybridization of whole genome-based oligonucleotide arrays with RNA samples from hind leg imaginal discs of pre-pupal honeybees of both castes we present a list of 200 differentially expressed genes. Notably, there are castes preferentially expressed cuticular protein genes and members of the P450 family. We also provide results of qPCR analyses determining the developmental transcription profiles of eight selected genes, including abdominal-A, distal-less and ultrabithorax (Ubx), whose roles in leg development have been previously demonstrated in other insect models. Ubx expression in workers hind leg is approximately 25 times higher than in queens. Finally, immunohistochemistry assays show that Ubx localization during hind leg development resembles the bristles localization in the tibia/basitarsus of the adult legs in both castes. Our data strongly indicate that the development of the hind legs diphenism characteristic of this corbiculate species is driven by a set of caste-preferentially expressed genes, such as those encoding cuticular protein genes, P450 and Hox proteins, in response to the naturally different diets offered to honeybees during the larval period.

  6. Hox gene expression leads to differential hind leg development between honeybee castes.

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    Ana Durvalina Bomtorin

    Full Text Available Beyond the physiological and behavioural, differences in appendage morphology between the workers and queens of Apis mellifera are pre-eminent. The hind legs of workers, which are highly specialized pollinators, deserve special attention. The hind tibia of worker has an expanded bristle-free region used for carrying pollen and propolis, the corbicula. In queens this structure is absent. Although the morphological differences are well characterized, the genetic inputs driving the development of this alternative morphology remain unknown. Leg phenotype determination takes place between the fourth and fifth larval instar and herein we show that the morphogenesis is completed at brown-eyed pupa. Using results from the hybridization of whole genome-based oligonucleotide arrays with RNA samples from hind leg imaginal discs of pre-pupal honeybees of both castes we present a list of 200 differentially expressed genes. Notably, there are castes preferentially expressed cuticular protein genes and members of the P450 family. We also provide results of qPCR analyses determining the developmental transcription profiles of eight selected genes, including abdominal-A, distal-less and ultrabithorax (Ubx, whose roles in leg development have been previously demonstrated in other insect models. Ubx expression in workers hind leg is approximately 25 times higher than in queens. Finally, immunohistochemistry assays show that Ubx localization during hind leg development resembles the bristles localization in the tibia/basitarsus of the adult legs in both castes. Our data strongly indicate that the development of the hind legs diphenism characteristic of this corbiculate species is driven by a set of caste-preferentially expressed genes, such as those encoding cuticular protein genes, P450 and Hox proteins, in response to the naturally different diets offered to honeybees during the larval period.

  7. Nutritionally driven differential gene expression leads to heterochronic brain development in honeybee castes.

    Science.gov (United States)

    Moda, Lívia Maria; Vieira, Joseana; Guimarães Freire, Anna Cláudia; Bonatti, Vanessa; Bomtorin, Ana Durvalina; Barchuk, Angel Roberto; Simões, Zilá Luz Paulino

    2013-01-01

    The differential feeding regimes experienced by the queen and worker larvae of the honeybee Apis mellifera shape a complex endocrine response cascade that ultimately gives rise to differences in brain morphologies. Brain development analyzed at the morphological level from the third (L3) through fifth (L5) larval instars revealed an asynchrony between queens and workers. In the feeding phase of the last larval instar (L5F), two well-formed structures, pedunculi and calyces, are identifiable in the mushroom bodies of queens, both of which are not present in workers until a later phase (spinning phase, L5S). Genome-wide expression analyses and normalized transcript expression experiments monitoring specific genes revealed that this differential brain development starts earlier, during L3. Analyzing brains from L3 through L5S1 larvae, we identified 21 genes with caste-specific transcription patterns (e.g., APC-4, GlcAT-P, fax, kr-h1 and shot), which encode proteins that are potentially involved in the development of brain tissues through controlling the cell proliferation rate (APC4, kr-h1) and fasciculation (GlcAT-P, fax, and shot). Shot, whose expression is known to be required for axon extension and cell proliferation, was found to be transcribed at significantly higher levels in L4 queens compared with worker larvae. Moreover, the protein encoded by this gene was immunolocalized to the cytoplasm of cells near the antennal lobe neuropiles and proximal to the Kenyon cells in the brains of L4 queens. In conclusion, during the larval period, the brains of queens are larger and develop more rapidly than workers' brains, which represents a developmental heterochrony reflecting the effect of the differential feeding regime of the two castes on nervous system development. Furthermore, this differential development is characterized by caste-specific transcriptional profiles of a set of genes, thus pointing to a link between differential nutrition and differential

  8. Nutritionally driven differential gene expression leads to heterochronic brain development in honeybee castes.

    Directory of Open Access Journals (Sweden)

    Lívia Maria Moda

    Full Text Available The differential feeding regimes experienced by the queen and worker larvae of the honeybee Apis mellifera shape a complex endocrine response cascade that ultimately gives rise to differences in brain morphologies. Brain development analyzed at the morphological level from the third (L3 through fifth (L5 larval instars revealed an asynchrony between queens and workers. In the feeding phase of the last larval instar (L5F, two well-formed structures, pedunculi and calyces, are identifiable in the mushroom bodies of queens, both of which are not present in workers until a later phase (spinning phase, L5S. Genome-wide expression analyses and normalized transcript expression experiments monitoring specific genes revealed that this differential brain development starts earlier, during L3. Analyzing brains from L3 through L5S1 larvae, we identified 21 genes with caste-specific transcription patterns (e.g., APC-4, GlcAT-P, fax, kr-h1 and shot, which encode proteins that are potentially involved in the development of brain tissues through controlling the cell proliferation rate (APC4, kr-h1 and fasciculation (GlcAT-P, fax, and shot. Shot, whose expression is known to be required for axon extension and cell proliferation, was found to be transcribed at significantly higher levels in L4 queens compared with worker larvae. Moreover, the protein encoded by this gene was immunolocalized to the cytoplasm of cells near the antennal lobe neuropiles and proximal to the Kenyon cells in the brains of L4 queens. In conclusion, during the larval period, the brains of queens are larger and develop more rapidly than workers' brains, which represents a developmental heterochrony reflecting the effect of the differential feeding regime of the two castes on nervous system development. Furthermore, this differential development is characterized by caste-specific transcriptional profiles of a set of genes, thus pointing to a link between differential nutrition and

  9. Epigenetic (re)programming of caste-specific behavior in the ant Camponotus floridanus

    Science.gov (United States)

    Brady, Cristina M.; Enzmann, Brittany L.; Desplan, Claude; Ray, Anandasankar; Zwiebel, Laurence J.; Bonasio, Roberto; Reinberg, Danny; Liebig, Jürgen; Berger, Shelley L.

    2016-01-01

    Eusocial insects organize themselves into behavioral castes whose regulation has been proposed to involve epigenetic processes, including histone modification. In the carpenter ant Camponotus floridanus, morphologically distinct worker castes called minors and majors exhibit pronounced differences in foraging and scouting behaviors. We found that these behaviors are regulated by histone acetylation likely catalyzed by the conserved acetyltransferase CBP. Transcriptome and chromatin analysis in brains of scouting minors fed pharmacological inhibitors of CBP and histone deacetylases (HDACs) revealed hundreds of genes linked to hyperacetylated regions targeted by CBP. Majors rarely forage, but injection of a HDAC inhibitor or small interfering RNAs against the HDAC Rpd3 into young major brains induced and sustained foraging in a CBP-dependent manner. Our results suggest that behavioral plasticity in animals may be regulated in an epigenetic manner via histone modification. PMID:26722000

  10. Epigenetic (re)programming of caste-specific behavior in the ant Camponotus floridanus.

    Science.gov (United States)

    Simola, Daniel F; Graham, Riley J; Brady, Cristina M; Enzmann, Brittany L; Desplan, Claude; Ray, Anandasankar; Zwiebel, Laurence J; Bonasio, Roberto; Reinberg, Danny; Liebig, Jürgen; Berger, Shelley L

    2016-01-01

    Eusocial insects organize themselves into behavioral castes whose regulation has been proposed to involve epigenetic processes, including histone modification. In the carpenter ant Camponotus floridanus, morphologically distinct worker castes called minors and majors exhibit pronounced differences in foraging and scouting behaviors. We found that these behaviors are regulated by histone acetylation likely catalyzed by the conserved acetyltransferase CBP. Transcriptome and chromatin analysis in brains of scouting minors fed pharmacological inhibitors of CBP and histone deacetylases (HDACs) revealed hundreds of genes linked to hyperacetylated regions targeted by CBP. Majors rarely forage, but injection of a HDAC inhibitor or small interfering RNAs against the HDAC Rpd3 into young major brains induced and sustained foraging in a CBP-dependent manner. Our results suggest that behavioral plasticity in animals may be regulated in an epigenetic manner via histone modification.

  11. Abrasive Wear Behavior of High Chromium Cast Iron and Hadfield Steel-- A Comparison

    Institute of Scientific and Technical Information of China (English)

    Mehdi Mazar Atabaki; Sajjad Jafari; Hassan Abdollah-pour

    2012-01-01

    Wear properties of two different crushers used for grinding raw materials of cement industry are compared using pin-on-disk wear test.The wear test was carried out with different loads on a pin.Abrasive wear behavior of two alloys was evaluated by comparing mass loss,wear resistance,microhardness and friction coefficient.The microstructure of the specimens was detected using optical microscope.The results showed that abrasive wear of high chromium cast iron is lower than that of Hadfield steel.Due to the presence of M7C3 carbides on the high chromium cast iron matrix,impact crushers exhibited higher friction coefficient

  12. Mechanical Behavior of Yttria-Stabilized Zirconia Aqueous Cast Tapes and Laminates

    Directory of Open Access Journals (Sweden)

    V. Moreno

    2014-01-01

    Full Text Available Aqueous tape casting was used to produce yttria-stabilized zirconia films for electrolyte-supported solid oxide fuel cell (SOFC. Tape casting slurries were prepared varying the binder content between 20 and 25 wt%. A commercial acrylic emulsion served as binder. Rheological measurements of the two slurries were performed. Both slurries showed a shear-thinning behavior. Tapes with 25 wt% binder exhibited adequate flexibility and a smooth and homogeneous surface, free of cracks and other defects. Suitable conditions of lamination were found and a theoretical density of 54% in the laminates was achieved. Laminated tapes showed higher tensile strength compared to single sheets. Tape orientation has a significant influence on the mechanical properties. Tensile strength, elongation to strain, and Young’s modulus measured in samples produced in the direction of casting showed higher property values.

  13. Comparison of corrosion behavior of ZL104 alloy at as-cast and heat treatment states

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The corrosion behavior of ZL 104 alloy at different states (as-cast and heat treatment) in salt spray corrosion (SSC) was studied. The results show that the sample treated after refinement and modification has the least corrosive resistance compared with the sample bearing as-cast structure at the beginning of the corrosion. As the corrosion process continued, however, the trend reversed itself. After 44 h continuous corrosion, the corrosive rates of all samples tend to be stable. After experiments, the sample bearing as-cast structure had the most corrosive products on the surface whereas the sample being refined and modified had the least products. The Fourier transformation infrared spectroscopy (FTIR)analyses of the corrosion products show that these products are composed of hydroxyl-containing substances.

  14. Influences of copper on solidification structure and hardening behavior of high chromium cast irons

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; XIONG Ji; FAN Hong-yuan; SHEN Bao-luo; GAO Sheng-ji

    2008-01-01

    The influences of copper on microstructure and the hardening behavior of high chromium cast irons subjected to sub-critical treatment were investigated.The results show that the mierostructure of the as-cast high chromium cast irons consists of retained austenite,martensite and M7 C3 type eutectic carbide.When copper is added into high chromium cast irons,austenite and carbide contents are increased.The increased addition of copper content from 0%to 1.84%leads to the increase of austenite and carbide from 15.9%and 20.0% to 61.0%and 35.5%,respectively.In the process of sub-critical treatment,the retained austenite in the matrix can be precipitated into secondary carbides and then transforms into martensite in cooling process,which causes the secondary hardening of the alloy under sub-critical treatment.High chromium cast irons containing copper in sub-critical treatment appear the second hardening curve peak due to the precipitation of copper from supersaturated matrix.

  15. Rheologic behaviors of A356 aluminum alloy billet produced by semisolid continuous casting process

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    The experiments for rheologic behaviors of semisolid continuous casting billets of A356 alloy in semisolid state had been carried out with a rnultifunctional rheometer. The results show that the deformation rate increases with loading time, the maximum strain reaches to 120 % ( which is one time larger than that of traditional mold casting billet) and the strain can be rapidly elirninated to 10% after unloading. Moreover, there is a critic stress for billet deformation even in semisolid state, which is named as critic shear stress. This stress increases with the decreasing of heating time. The rheologic behaviors can be expressed by five elements mechanical model (H2 - [N1 | H2] - [N2|S] ) and can be modified with the increasing of heating time.

  16. Characterization of Genomic Variants Associated with Scout and Recruit Behavioral Castes in Honey Bees Using Whole-Genome Sequencing.

    Directory of Open Access Journals (Sweden)

    Bruce R Southey

    Full Text Available Among forager honey bees, scouts seek new resources and return to the colony, enlisting recruits to collect these resources. Differentially expressed genes between these behaviors and genetic variability in scouting phenotypes have been reported. Whole-genome sequencing of 44 Apis mellifera scouts and recruits was undertaken to detect variants and further understand the genetic architecture underlying the behavioral differences between scouts and recruits. The median coverage depth in recruits and scouts was 10.01 and 10.7 X, respectively. Representation of bacterial species among the unmapped reads reflected a more diverse microbiome in scouts than recruits. Overall, 1,412,705 polymorphic positions were analyzed for associations with scouting behavior, and 212 significant (p-value 1000 bp apart from each other. A number of these variants were mapped to ncRNA LOC100578102, solute carrier family 12 member 6-like gene, and LOC100576965 (meprin and TRAF-C homology domain containing gene. Functional categories represented among the genes corresponding to significant variants included: neuronal function, exoskeleton, immune response, salivary gland development, and enzymatic food processing. These categories offer a glimpse into the molecular support to the behaviors of scouts and recruits. The level of association between genomic variants and scouting behavior observed in this study may be linked to the honey bee's genomic plasticity and fluidity of transition between castes.

  17. Characterization of Genomic Variants Associated with Scout and Recruit Behavioral Castes in Honey Bees Using Whole-Genome Sequencing.

    Science.gov (United States)

    Southey, Bruce R; Zhu, Ping; Carr-Markell, Morgan K; Liang, Zhengzheng S; Zayed, Amro; Li, Ruiqiang; Robinson, Gene E; Rodriguez-Zas, Sandra L

    2016-01-01

    Among forager honey bees, scouts seek new resources and return to the colony, enlisting recruits to collect these resources. Differentially expressed genes between these behaviors and genetic variability in scouting phenotypes have been reported. Whole-genome sequencing of 44 Apis mellifera scouts and recruits was undertaken to detect variants and further understand the genetic architecture underlying the behavioral differences between scouts and recruits. The median coverage depth in recruits and scouts was 10.01 and 10.7 X, respectively. Representation of bacterial species among the unmapped reads reflected a more diverse microbiome in scouts than recruits. Overall, 1,412,705 polymorphic positions were analyzed for associations with scouting behavior, and 212 significant (p-value 1000 bp apart from each other. A number of these variants were mapped to ncRNA LOC100578102, solute carrier family 12 member 6-like gene, and LOC100576965 (meprin and TRAF-C homology domain containing gene). Functional categories represented among the genes corresponding to significant variants included: neuronal function, exoskeleton, immune response, salivary gland development, and enzymatic food processing. These categories offer a glimpse into the molecular support to the behaviors of scouts and recruits. The level of association between genomic variants and scouting behavior observed in this study may be linked to the honey bee's genomic plasticity and fluidity of transition between castes.

  18. Solid-particle erosion behavior of cast alloys used in the mining industry

    Science.gov (United States)

    Atapek, Ş. Hakan; Fidan, Sinan

    2015-12-01

    The erosive-wear response of five commercial ferrous-based cast alloys used for crushing was examined in this study. The microstructures of the alloys were modified to elucidate the effect of microstructural features on wear. Erosion tests were conducted using aluminum oxide particles (90-125 μm) at 70 m/s and a normal impact angle (90°). The worn surfaces were characterized by scanning electron microscopy and 3D non-contact laser profilometry. It is found that (i) a pearlitic structure exhibiting a greater plastic deformation than both bainitic and martensitic structures shows the greatest resistance to erosive wear at normal impact and (ii) the fracture characteristics of carbide and graphite particles plays an important role in determining the erosion wear behavior of the cast alloy matrices.

  19. Solid-particle erosion behavior of cast alloys used in the mining industry

    Institute of Scientific and Technical Information of China (English)

    Hakan Atapek; Sinan Fidan

    2015-01-01

    The erosive-wear response of five commercial ferrous-based cast alloys used for crushing was examined in this study. The micro-structures of the alloys were modified to elucidate the effect of microstructural features on wear. Erosion tests were conducted using alumi-num oxide particles (90–125 µm) at 70 m/s and a normal impact angle (90°). The worn surfaces were characterized by scanning electron mi-croscopy and 3D non-contact laser profilometry. It is found that (i) a pearlitic structure exhibiting a greater plastic deformation than both bainitic and martensitic structures shows the greatest resistance to erosive wear at normal impact and (ii) the fracture characteristics of car-bide and graphite particles plays an important role in determining the erosion wear behavior of the cast alloy matrices.

  20. Thermo-Mechanical Behavior of the Continuous Casting Bloom in the Heavy Reduction Process

    Science.gov (United States)

    Ji, Cheng; Wu, Chen-hui; Zhu, Miao-yong

    2016-08-01

    A two-stage sequential heavy reduction (HR) method, in which the reduction amount was increased both before and after the solidification end, is presented to simultaneously improve the homogeneity and compactness of the continuous casting bloom. With bearing steel GCr15 chosen as the specific research steel, a three-dimensional thermal-mechanical finite element model was developed to simulate and analyze the thermal and mechanical behaviors of the continuous casting bloom during the HR process. In order to ensure the accuracy of the simulation, the constitutive model parameters were derived from the experimental results. The predicted temperature distribution and shell thickness were verified using a thermal infrared camera and nail shooting results, respectively. The real measured relationship between the HR pressure and amount were applied to verify the mechanical model. The explorative application results showed that the quality of the bloom center and compactness of rolled bars have both been significantly improved after the HR was applied.

  1. AN INVESTIGATION OF DIFFERENTIAL REINFORCEMENT OF ALTERNATIVE BEHAVIOR WITHOUT EXTINCTION

    OpenAIRE

    Athens, Elizabeth S; Vollmer, Timothy R

    2010-01-01

    We manipulated relative reinforcement for problem behavior and appropriate behavior using differential reinforcement of alternative behavior (DRA) without an extinction component. Seven children with developmental disabilities participated. We manipulated duration (Experiment 1), quality (Experiment 2), delay (Experiment 3), or a combination of each (Experiment 4), such that reinforcement favored appropriate behavior rather than problem behavior even though problem behavior still produced rei...

  2. Behavior of Non-metallic Inclusions in Centrifugal Induction Electroslag Castings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    (para)In order to know the behavior of non-metallic inclusions in centrifugal induction electroslag castings (CIESC), non-metallic inclusions in 5CrMnMo and 4Cr5MoSiV1 were qualitatively and quantitatively analyzed. The largest size of inclusions in the casting and the thermodynamic possibility of TiN precipitation in steel were also calculated. The results show that sulfide inclusions are evenly distributed and the content is low. The amount of oxide inclusions in CIESC 4Cr5MoSiV1 steel is close to the ESR steel and lower than that in the EAF steel, and there are some differences along radial direction. Nitride inclusions are fine and the diameter of the largest one is 3~4um. With the increase of the centrifugal machine's rotational speed, the ratio of round inclusions increases and the ratio of sharp inclusions decreases. According to the experiment and the calculation results, it is pointed out that the largest diameter of non-metallic inclusions in the CIESC 4Cr5MoSiV1 casting is only 6.6mu, and [N%][Ti%] in 4Cr5MoSiV1 steel should be controlled less than 4.4~#U00d7tex010^{-5} in order to further reduce the amount and size of TiN inclusions.

  3. Effect of heat treatment on corrosion behavior of low pressure sand cast Mg-10Gd-3Y-0.5Zr alloys

    OpenAIRE

    2016-01-01

    The corrosion behaviors of low-pressure sand cast Mg-10Gd-3Y-0.5Zr (wt.%) alloys in as-cast, solution treated (T4) and aged (T6) conditions were studied by means of immersion test and electrochemical measurements in 5wt.% NaCl solution saturated with Mg(OH)2. It was observed that the corrosion rate in the T4 condition was lower than that of the as-cast and T6 conditions by both sand casting and permanent mold casting with the same order of as-cast>T6>T4; while the corrosion resistance of the ...

  4. Influence of neodymium on high cycle fatigue behavior of die cast AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    杨友; 李雪松

    2010-01-01

    High cycle fatigue behavior of die cast AZ91D magnesium alloy with different Nd contents was investigated.Axial mechanical fatigue tests were conducted at the stress ratio R=0.1 and the fatigue strength was evaluated using up-to-down load method on specimens of AZ91D with different Nd contents.The results showed that the grain of AZ91D alloy was refined,the size and amount of β-Mg17Al12 phase decreased and distributed uniformly with increasing Nd content.At the number of cycles to failure,Nf=107,the fatigue...

  5. Transformation Behavior and Microstructure in a 40Cr2Ni2MoV Cast Steel

    Institute of Scientific and Technical Information of China (English)

    Cheng Liu; Zhenbo Zhao; Sanjiwan. D. Bhole1; Derek O. Northwood

    2004-01-01

    The transformation behavior of a 40Cr2Ni2MoV cast steel manufactured by electroslag remelting (ESR) has been investigated. Compared to a forged steel, the incubation periods for both the pearlite and bainite transformations are shorter, but the transformation times are longer. The austenite is easier to transform into martensite. Optical microscopy and TEM indicated that there were variations in microstructure during the super-cooled austenite transformation. This is attributed to an inhomogeneous austenite, resulting from the segregation of elements during the ESR solidification.

  6. Study on the Thermal Fatigue Behavior of Hot Deformed Wear Resistance Cast Iron and Effect of Carbide

    Institute of Scientific and Technical Information of China (English)

    Dong Litao; Liu Rongchang; Li Xingyuan; Chen Xiuhong

    2007-01-01

    The thermal fatigue behavior of wear resistance cast iron with different quantity of deformation has been investigated. The results show that eutectic carbide is the main location and passage for initiation and extension of thermal fatigue cracks, approving that the more serious, the carbide breaks. The higher thermal fatigue resistance of wear resistance cast iron will be and thermal fatigue fracture belongs mainly to brittleness.

  7. Slurry Erosion Behavior of Destabilized and Deep Cryogenically Treated Cr-Mn-Cu White Cast Irons

    Directory of Open Access Journals (Sweden)

    S. Gupta

    2016-12-01

    Full Text Available The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7 and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance.

  8. Cold resistance depends on acclimation and behavioral caste in a temperate ant

    Science.gov (United States)

    Modlmeier, Andreas P.; Pamminger, Tobias; Foitzik, Susanne; Scharf, Inon

    2012-10-01

    Adjusting to low temperatures is important for animals living in cold environments. We studied the chill-coma recovery time in temperate ant workers ( Temnothorax nylanderi) from colonies collected in autumn and spring in Germany. We experimentally acclimated these ant colonies to cold temperatures followed by warm temperatures. As expected, cold-acclimated workers recovered faster from freezing temperatures, but subsequent heat acclimation did not change the short recovery times observed after cold acclimation. Hence, either heat acclimation improves cold tolerance, possibly as a general response to stress, or at least it does not negate enhanced cold tolerance following cold acclimation. Colonies collected in spring showed similar cold tolerance levels to cold-acclimated colonies in the laboratory. Next, we compared the chill-coma recovery time of different worker castes and found that exterior workers recovered faster than interior workers. This difference may be related to their more frequent exposure to cold, higher activity level, or distinct physiology. Interior workers were also heavier and showed a higher gaster-to-head ratio and thorax ratio compared to exterior workers. An obvious difference between exterior and interior workers is activity level, but we found no link between activity and cold tolerance. This suggests that physiology rather than behavioral differences could cause the increased cold tolerance of exterior workers. Our study reveals the importance of acclimation for cold tolerance under natural and standardized conditions and demonstrates differences in cold tolerance and body dimensions in monomorphic behavioral castes of an ant.

  9. Effect of Casting Parameters on the Microstructural and Mechanical Behavior of Magnesium AZ31-B Alloy Strips Cast on a Single Belt Casting Simulator

    Directory of Open Access Journals (Sweden)

    Ahmad Changizi

    2014-01-01

    Full Text Available Strips of magnesium alloy AZ31-B were cast on a simulator of a horizontal single belt caster incorporating a moving mold system. Mixtures of CO2 and sulfur hexafluoride (SF6 gases were used as protective atmosphere during melting and casting. The castability of the AZ31-B strips was investigated for a smooth, low carbon steel substrate, and six copper substrates with various textures and roughnesses. Graphite powder was used to coat the substrates. The correlation between strip thickness and heat flux was investigated. It was found that the heat flux from the forming strip to the copper substrate was higher than that to the steel substrate, while coated substrates registered lower heat fluxes than uncoated substrates. The highest heat flux from the strip was recorded for casting on macrotextured copper substrates with 0.15 mm grooves. As the thickness of the strip decreased, the net heat flux decreased. As the heat flux increased, the grain sizes of the strips were reduced, and the SDAS decreased. The mechanical properties were improved when the heat flux increased. The black layers which formed on the strips’ surfaces were analyzed and identified as nanoscale MgO particles. Nano-Scale particles act as light traps and appeared black.

  10. Solidification Behavior and Segregation of Re-containing Cast Ni-base Superalloy with Different Cr Content

    Institute of Scientific and Technical Information of China (English)

    Xiurong Guan; Enze Liu; Zhi Zheng; Yongsi Yu; Jian Tong; Yuchun Zhai

    2011-01-01

    The effect of chromium (Cr) on solidification and segregation behavior of Re-containing cast Ni-base superalloys was investigated by optical microscopy (OM), scanning electron microscopy (SEM) and electronic probe micro analysis (EPMA). The results show that Cr has significant effect on solidification and segregation behavior of Re-containing cast Ni-base superalloys. The liquidus and solidus of alloy decrease with increasing Cr in alloys. The segregation coefficient (K) of Mo increases and that of W and Re decreases gradually with increasing Cr element.

  11. Secondary recrystallization behavior in a twin-roll cast grain-oriented electrical steel

    Science.gov (United States)

    Song, Hong-Yu; Liu, Hai-Tao; Wang, Yin-Ping; Wang, Guo-Dong

    2017-04-01

    The microstructure and texture evolution along the processing was investigated with a particular focus on the secondary recrystallization behavior in a 0.23 mm-thick twin-roll cast grain-oriented electrical steel. A striking feature is that Goss orientation originated during twin-roll casting as a result of shear deformation and it was further enhanced during hot rolling and normalizing. After primary recrystallization annealing, a homogeneous microstructure associated with a sharp γ-fiber texture was produced. During secondary recrystallization annealing, the γ-fiber texture was first strengthened and weakened with increasing temperature prior to the onset of secondary recrystallization. Goss grains always exhibited more 20-45° misoriented boundaries than the matrix. The matrix was quite stable during secondary recrystallization with the aid of dense inhibitors. Finally, a complete secondary recrystallization microstructure consisting of large Goss grains was produced. The grain boundary characteristics distribution indicated that the high energy model was responsible for the abnormal growth of Goss grains under the present conditions.

  12. Microstructure, tensile properties and fracture behavior of high temperature Al–Si–Mg–Cu cast alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, A.M.A., E-mail: madel@uqac.ca [Center for Advanced Materials, Qatar University, Doha (Qatar); Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering, Suez Canal University, Box 43721, Suez (Egypt); Samuel, F.H. [Université du Québec à Chicoutimi, Chicoutimi, QC, Canada G7H 2B1 (Canada); Al Kahtani, Saleh [Industrial Engineering Program, Mechanical Engineering Department, College of Engineering, Salman bin Abdulaziz University, Al Kharj (Saudi Arabia)

    2013-08-10

    The high temperature tensile behavior of 354 aluminum cast alloy was investigated in the presence of Zr and Ni. The cast alloys were given a solutionizing treatment followed by artificial aging at 190 °C for 2 h. High temperature tensile tests were conducted at various temperatures from 25 °C to 300 °C. Optical microscopy and electron probe micro-analyzer were used to study the microstructure of different intermetallic phases formed. The fractographic observations of fracture surface were analyzed by scanning electron microscopy to understand the fracture mechanism. The results revealed that the intermetallics phases of (Al, Si){sub 3}(Zr, Ti), Al{sub 3}CuNi and Al{sub 9}NiFe are the main feature in the microstructures of alloys with Zr and Ni additions. The results also indicated that the tensile strength of alloy decreases with an increase in temperature. The combined addition of 0.2 wt% Zr and 0.2 wt% Ni leads to a 30% increase in the tensile properties at 300 °C compared to the base alloy. Zr and Ni bearing phases played a vital role in the fracture mechanism of the alloys studied.

  13. Corrosion Behavior of AlSi10Mg Alloy Produced by Additive Manufacturing (AM vs. Its Counterpart Gravity Cast Alloy

    Directory of Open Access Journals (Sweden)

    Avi Leon

    2016-06-01

    Full Text Available The attractiveness of additive manufacturing (AM relates to the ability of this technology to rapidly produce very complex components at affordable costs. However, the properties and corrosion behavior, in particular, of products produced by AM technology should at least match the properties obtained by conventional technologies. The present study aims at evaluating the corrosion behavior and corrosion fatigue endurance of AlSi10Mg alloy produced by selective laser melting (SLM in comparison with its conventional counterpart, gravity cast alloy. The results obtained indicate that the corrosion resistance of the printed and cast alloys was relatively similar, with a minor advantage to the printed alloy. The corrosion fatigue endurance of the printed alloy was relatively improved compared to the cast alloy. This was mainly attributed to the significant differences between the microstructure and defect characteristics of those two alloys.

  14. Caste and Choice: The Influence of Developmental Idealism on Marriage Behavior.

    Science.gov (United States)

    Allendorf, Keera; Thornton, Arland

    2015-07-01

    Is the marriage behavior of young people determined by their socioeconomic characteristics or their endorsement of developmental idealism? This article addresses this question using a unique longitudinal data set from Nepal and provides the first individual-level test of developmental idealism theory. The authors find that unmarried individuals with greater endorsement of developmental idealism in 2008 were more likely by 2012 to choose their own spouse, including a spouse of a different caste, rather than have an arranged marriage. Those with salaried work experience were also less likely to have arranged marriages, but urban proximity and education were not significant. The authors conclude that both developmental idealism and socioeconomic characteristics influence marriage and that their influences are largely independent.

  15. Isothermal oxidation behavior of cast Ni-base superalloy K44

    Institute of Scientific and Technical Information of China (English)

    LI Yun; LIU Xue-gui; GUO Jian-ting; YUAN Chao; YANG Hong-cai

    2006-01-01

    The oxidation behavior of a cast Ni-base superalloy K44 in air at 850-1 000 ℃ for l00 h was studied. The scales on the surface were determined by SEM and EPMA equipped with an EDXS. The results show that oxidation kinetics obey the parabolic law from which the values of activation energy Qp1=221.1 kJ/mol and Qp2=247.6 kJ/mol are estimated. The oxidation scales are composed of loose outer layer of TiO2/TiO-Cr2O3 and a small amount of NiCr2O4 and NiA12O4, compact intermediate layer Cr2O3, and precipitate of internal oxides A12O3.

  16. Electrochemical and wetting behavior of as-cast Sn-Zn-Sb lead free solders alloys

    Directory of Open Access Journals (Sweden)

    Mladenović Srba A.

    2013-01-01

    Full Text Available Ternary alloys SnZn12Sb8, SnZn10Sb10, SnZn8Sb12, SnZn6Sb14, and SnZn2Sb18 were prepared by induction melting. Electrochemical behavior and wetting (contact angle of prepared as-cast samples were investigated using open circuit potential measurement and sessile drop technique. The results of electrochemical investigation show that open-circuit potential, few seconds after immersing of electrodes, shifts toward more negative values, indicating a relatively smaller rate of dissolution during the spontaneous dissolution process under the curentless conditions. After that period, the values of potential tend to be constant with time. It was found that all investigated alloys have poor wettability on copper substrate and the contact angle values decrease with increasing superheat temperature.

  17. Droplet impinging behavior on surfaces: Part II - Water on aluminium and cast iron surfaces

    Science.gov (United States)

    Sangavi, S.; Balaji, S.; Mithran, N.; Venkatesan, M.

    2016-09-01

    Droplet cooling of metal surfaces is an important area of research in industrial applications such as material quenching, nozzle spraying, etc. Fluids (water) act as an excellent agent in heat transfer to remove excess heat in various processes by convection and conduction. Such cooling process varies the material properties. The bubbles formed during droplet impinging on the surface act as heat sink and causes variation of height and spreading radius of the droplet with increase in temperature. In the present work, an experimental study of the droplet impinging behavior on Aluminium and Cast iron surfaces is reported. The water droplets are made to fall on the surface of the specimens from a specific height, which also influences the spreading radius. The effect of temperature on droplet height and droplet spreading radius is detailed.

  18. Study on the hot corrosion behavior of a cast Ni-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.; Guo, J.T.; Zhang, J.; Yuan, C.; Zhou, L.Z.; Hu, Z.Q. [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

    2010-07-01

    Hot corrosion behavior of Nickel-base cast superalloy K447 in 90% Na{sub 2}SO{sub 4} + 10% NaCl melting salt at 850 C and 900 C was studied. The hot corrosion kinetic of the alloy follows parabolic rate law under the experimental conditions. The external layer is mainly Cr{sub 2}O{sub 3} scale which is protective to the alloy, the intermediate layer is the Ti-rich phase, and the internal layer is mainly the international oxides and sulfides. With increased corrosion time and temperature, the oxide scales are gradually dissolved in the molten salt and then precipitate as a thick and non-protective scale. Chlorides cause the formation of volatile species, which makes the oxide scale disintegrate and break off. The corrosion kinetics and morphology examinations tend to support the basic dissolution model for hot corrosion mechanisms. (orig.)

  19. Intrinsic worker mortality depends on behavioral caste and the queens' presence in a social insect.

    Science.gov (United States)

    Kohlmeier, Philip; Negroni, Matteo Antoine; Kever, Marion; Emmling, Stefanie; Stypa, Heike; Feldmeyer, Barbara; Foitzik, Susanne

    2017-04-01

    According to the classic life history theory, selection for longevity depends on age-dependant extrinsic mortality and fecundity. In social insects, the common life history trade-off between fecundity and longevity appears to be reversed, as the most fecund individual, the queen, often exceeds workers in lifespan several fold. But does fecundity directly affect intrinsic mortality also in social insect workers? And what is the effect of task on worker mortality? Here, we studied how social environment and behavioral caste affect intrinsic mortality of ant workers. We compared worker survival between queenless and queenright Temnothorax longispinosus nests and demonstrate that workers survive longer under the queens' absence. Temnothorax ant workers fight over reproduction when the queen is absent and dominant workers lay eggs. Worker fertility might therefore increase lifespan, possibly due to a positive physiological link between fecundity and longevity, or better care for fertile workers. In social insects, division of labor among workers is age-dependant with young workers caring for the brood and old ones going out to forage. We therefore expected nurses to survive longer than foragers, which is what we found. Surprisingly, inactive inside workers showed a lower survival than nurses but comparable to that of foragers. The reduced longevity of inactive workers could be due to them being older than the nurses, or due to a positive effect of activity on lifespan. Overall, our study points to behavioral caste-dependent intrinsic mortality rates and a positive association between fertility and longevity not only in queens but also in ant workers.

  20. High-temperature low cycle fatigue behavior of a gray cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Fan, K.L., E-mail: 12klfan@tongji.edu.cn; He, G.Q.; She, M.; Liu, X.S.; Lu, Q.; Yang, Y.; Tian, D.D.; Shen, Y.

    2014-12-15

    The strain controlled low cycle fatigue properties of the studied gray cast iron for engine cylinder blocks were investigated. At the same total strain amplitude, the low cycle fatigue life of the studied material at 523 K was higher than that at 423 K. The fatigue behavior of the studied material was characterized as cyclic softening at any given total strain amplitude (0.12%–0.24%), which was attributed to fatigue crack initiation and propagation. Moreover, this material exhibited asymmetric hysteresis loops due to the presence of the graphite lamellas. Transmission electron microscopy analysis suggested that cyclic softening was also caused by the interactions of dislocations at 423 K, such as cell structure in ferrite, whereas cyclic softening was related to subgrain boundaries and dislocation climbing at 523 K. Micro-analysis of specimen fracture appearance was conducted in order to obtain the fracture characteristics and crack paths for different strain amplitudes. It showed that the higher the temperature, the rougher the crack face of the examined gray cast iron at the same total strain amplitude. Additionally, the microcracks were readily blunted during growth inside the pearlite matrix at 423 K, whereas the microcracks could easily pass through pearlite matrix along with deflection at 523 K. The results of fatigue experiments consistently showed that fatigue damage for the studied material at 423 K was lower than that at 523 K under any given total strain amplitude. - Highlights: • The low cycle fatigue behavior of the HT250 for engine cylinder blocks was investigated. • TEM investigations were conducted to explain the cyclic deformation response. • The low cycle fatigue cracks of HT250 GCI were studied by SEM. • The fatigue life of the examined material at 523 K is higher than that at 423 K.

  1. Microstructure and elevated-temperature tensile properties of differential pressure sand cast Mg-4Y-3Nd-0.5Zr alloy

    Directory of Open Access Journals (Sweden)

    Hong-hui Liu

    2016-01-01

    Full Text Available The microstructures of an Mg-4Y-3Nd-0.5Zr alloy by differential pressure casting were investigated using scanning electron microscopy (SEM and transmission electron microscopy (TEM, and its tensile deformation behavior was measured using a Gleeble1500D themo-simulation machine in the temperature range of 200 to 400 °C at initial strain rates of 5×10-4 to 10-1 s-1. Results show that the as-cast microstructure consists of primary α-Mg phase and bone-shaped Mg5RE eutectic phase distributed along the grain boundary. The eutectic phase is dissolved into the matrix after solution treatment and subsequently precipitates during peak aging. Tensile deformation tests show that the strain rate has little effect on stress under 300 °C. Tensile stress decreases with an increase in temperature and the higher strain rate leads to an increase in stress above 300 °C. The fracture mechanism exhibits a mixed quasi-cleavage fracture at 200 °C, while the fracture above 300 °C is a ductile fracture. The dimples are melted at 400 °C with the lowest strain rate of 10-4 s-1.

  2. Research of quasi-solid fracture behavior of casting Al-4.5Cu alloys

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The influencing mechanisms of elements Ti and Ce and their interactions on fracture behaviors of casting alloys Al-4.5Cu-0.6Mn were studied by observing tensile fracture behavior in quasi-solid zone under SEM and EDX instruments.The results indicate that the resistance stress against hot cracking can be improved obviously by addition of Ti, because of its grain refining function. It is also found that, when Ce is added into the alloys, besides its effect in refining crystalline, the mechanical behavior of lower melting point eutectic phase in quasi-solid zone can be improved efficiently by some compounds with Ce formed and deposited between dendrites. Therefore, a coiligating effect of Ti and Ce on improving resistance stress against hot cracking is more efficient than that only single alloy element is applied. When hot cracking occurs, grains yield at first, and then crack spreads. Both inter-grain and trans-grain fractures are observed, but the major fracture manner is brittleness.

  3. Effect of Zr on behavior of compressive creep in as cast ZA27 alloy

    Institute of Scientific and Technical Information of China (English)

    魏晓伟; 沈保罗

    2003-01-01

    The effect of Zr on the behavior of compressive creep in as cast ZA27 alloy was investigated in the temperature range of 20-160 ℃ and under different compressive stresses in the range of 50-137.5 MPa with special apparatus. The results show that the primary compressive creep strains and steady creep rates of ZA27-Zr alloy and ZA27 alloy increase with increasing temperature and stress. However, the primary compressive creep strain and steady creep rate of the ZA27-Zr alloy are lower than that of the ZA27 alloy below 100 ℃, but higher at 160 ℃. The compressive creep behaviors in both ZA27-Zr alloy and ZA27 alloy obey an empirical equation lnt=C-nlnσ+Q/RT, and the exponent stress n is 3.63 for ZA27-Zr alloy and 3.46 for ZA27 alloy, respectively, the activation energy Q is 87.32 kJ/mol for ZA27-Zr alloy and 81.09 kJ/mol for ZA27 alloy. Different material structural constants are associated with different compressive creep behaviors in the alloy. The compressive creep rate in the alloy is controlled by the lattice diffusion of zinc and dislocation limb.

  4. Research of quasi-solid fracture behavior of casting AI-4.5Cu alloys

    Directory of Open Access Journals (Sweden)

    Shengquan DONG

    2005-02-01

    Full Text Available The influencing mechanisms of elements Ti and Ce and their interactions on fracture behaviors of casting alloys AI-4.5Cu-0.6Mn were studied by observing tensile fracture behavior in quasi-solid zone under SEM and EDX instruments.The results indicate that the resistance stress against hot cracking can be improved obviously by addition of Ti, because of its grain refining function. It is also found that, when Ce is added into the alloys, besides its effect in refining crystalline, the mechanical behavior of lower melting point eutectic phase in quasi-solid zone can be improved efficiently by some compounds with Ce formed and deposited between dendrites. Therefore, a colligating effect of Ti and Ce on improving resistance stress against hot cracking is more efficient than that only single alloy element is applied. When hot cracking occurs, grains yield at first, and then crack spreads. Both inter-grain and trans-grain fractures are observed, but the major fracture manner is brittleness.

  5. Rheological Behavior of Slurries Containing Short Glass Fibers for Preparation of Investment Casting Shell

    Directory of Open Access Journals (Sweden)

    MA Hai-jiao

    2016-08-01

    Full Text Available The short glass fibers were introduced into the slurries by 0%-0.5% (mass fraction of refractory powders for preparation of fiber-reinforced shells for investment casting. The rheological properties of coatings containing different amounts of glass fibers were measured by R/S rheometer and the rheological behaviors of coatings were investigated. The results show that the apparent viscosities of coatings containing different amounts of glass fibers decrease with increasing shear rate, i.e., shear thinning behavior, similar to that of the coating without fibers. At the same shear rate, the apparent viscosities of coatings containing fibers are higher than that of the coating without fibers and the apparent viscosities of coatings containing 0.3% (mass fraction fibers are higher than that of the others. The high shear viscosities of coatings containing fibers increase initially, but later decrease, with increasing amount of fibers. The high shear viscosity of the coating containing 0.3% fibers reaches a maximum value of 102.6×10-3Pa·s, increased by about 31.9%, in comparison to the coating without fibers. And this coating with a maximum thixotropical loop area value of 11.8Pa·s-1 exhibits an excellent thixotropical behavior. However, it is not found that there is a noticeable effect of the amount of glass fibers on the yield stress or suspensibility of coatings.

  6. Tensile behavior of CF8-CPF8-304H and CF8M-CPF8M-316H stainless steel static and centrifugal castings

    Energy Technology Data Exchange (ETDEWEB)

    McEnerney, J.W.; Sikka, V.K.; Booker, M.K.

    1981-10-01

    We have analyzed the tensile behavior of 11 heats of grades CF8-CPF8-304H and 13 heats of grades CF8M-CPF8M-316H static and centrifugal castings from room temperature to 650/sup 0/C. Except for anomalous conditions, the centrifugal castings exhibited uniform composition. All CPF8-304H centrifugal castings contained only radial columnar grains, but some CPF8M-316H castings had columnar, banded, or equiaxed structures. Ultimate tensile strength and total elongation were the properties in which castings showed the most inferiority to wrought material. With increasing ferrite content, 0.2% yield strength and ultimate tensile strength increased while uniform elongation, total elongation, and reduction of area decreased. Although centrifugal castings did not exhibit significant end-to-end variation in tensile behavior, the 0.2% yield strength displayed anisotropy, with axial and circumferential values being greater than radial.

  7. An Investigation of Differential Reinforcement of Alternative Behavior without Extinction

    Science.gov (United States)

    Athens, Elizabeth S.; Vollmer, Timothy R.

    2010-01-01

    We manipulated relative reinforcement for problem behavior and appropriate behavior using differential reinforcement of alternative behavior (DRA) without an extinction component. Seven children with developmental disabilities participated. We manipulated duration (Experiment 1), quality (Experiment 2), delay (Experiment 3), or a combination of…

  8. Erosion-corrosion behavior of austenitic cast iron in an acidic slurry medium

    Science.gov (United States)

    Yang, Ke; Sun, Lan; Liu, Yu-zhen; Fan, Hong-yuan

    2015-06-01

    A series of austenitic cast iron samples with different compositions were cast and a part of nickel in the samples was replaced by manganese for economic reason. Erosion-corrosion tests were conducted under 2wt% sulfuric acid and 15wt% quartz sand. The results show that the matrix of cast irons remains austenite after a portion of nickel is replaced with manganese. (Fe,Cr)3C is a common phase in the cast irons, and nickel is the main alloying element in high-nickel cast iron; whereas, (Fe,Mn)3C is observed with the increased manganese content in low-nickel cast iron. Under erosion-corrosion tests, the weight-loss rates of the cast irons increase with increasing time. Wear plays a more important role than corrosion in determining the weight loss. It is indicated that the processes of weight loss for the cast irons with high and low nickel contents are different. The erosion resistance of the cast iron containing 7.29wt% nickel and 6.94wt% manganese is equivalent to that of the cast iron containing 13.29wt% nickel.

  9. Flow and thermal behavior of the top surface flux/powder layers in continuous casting molds

    Science.gov (United States)

    McDavid, R. M.; Thomas, B. G.

    1996-08-01

    Steady-state finite-element models have been formulated to investigate the coupled fluid flow and thermal behavior of the top-surface flux layers in continuous casting of steel slabs. The three-dimensional (3-D) FIDAP model includes the shear stresses imposed on the flux/steel interface by flow velocities calculated in the molten steel pool. It also includes different temperature-dependent powder properties for solidification and melting. Good agreement between the 3-D model and experimental measurements was obtained. The shear forces, imposed by the steel surface motion toward the submerged entry nozzle (SEN), create a large recirculation zone in the liquid flux pool. Its depth increases with increasing casting speed, increasing liquid flux conductivity, and decreasing flux viscosity. For typical conditions, this zone contains almost 4 kg of flux, which contributes to an average residence time of about 2 minutes. Additionally, because the shear forces produced by the narrowface consumption and the steel flow oppose each other, the flow in the liquid flux layer separates at a location centered 200 mm from the narrowface wall. This flow separation depletes the liquid flux pool at this location and may contribute to generically poor feeding of the mold-strand gap there. As a further consequence, a relatively cold spot develops at the wideface mold wall near the separation point. This nonuniformity in the temperature distribution may result in nonuniform heat removal, and possibly nonuniform initial shell growth in the meniscus region along the wideface off-corner region. In this way, potential steel quality problems may be linked to flow in the liquid flux pool.

  10. Hot Corrosion Behavior of High-Chromium, High-Carbon Cast Irons in NaCl-KCl Molten Salts

    Directory of Open Access Journals (Sweden)

    S. Vuelvas-Rayo

    2012-01-01

    Full Text Available A study on the corrosion behavior of a series of experimental high-chromium (18.53–30.48 wt.%, high-carbon (3.82–5.17% cast irons in NaCl-KCl (1 : 1 M at 670°C has been evaluated by using weight loss technique and compared with a 304-type stainless steel. It was found that all castings had a higher corrosion rate than conventional 304SS and that the addition of Cr increased the degradation rate of the cast irons. Additionally, corrosion rate increased by increasing the C contents up to 4.29%, but it decreased with a further increase in its contents. Results are discussed in terms of consumption of the Cr2O3 layer by the melt.

  11. Galvanic corrosion behavior of die cast AZ91D magnesium alloy in chloride solution

    Institute of Scientific and Technical Information of China (English)

    Zhensong Tong; Wei Zhang; Jiuqing Li; Jin Gao; Jiquan He; Ji Zhou

    2004-01-01

    The galvanic corrosion behavior of die cast AZ91D magnesium alloy coupled with H62 brass, 316L stainless steel, A3steel and LY12 aluminum alloy of different areas in 3.5% NaC1 solution was studied. The free corrosion potentials, galvanic potentials and currents of these galvanic couples were measured. The galvanic effects were determined by the mass loss and regression method using three points. The results show that: (1) In these four kinds of couples AZ91D acts as the anode, whose galvanic corrosion behavior is mainly controlled by the cathodic polarization; (2) The free corrosion potentials of these four kinds of couples change a liffle with time and cathodic/anodic area ratio (CAAR); (3) The galvanic potential of AZ91D/LY12 moves positively with the increase of time and CAAR; (4) The galvanic currents increase with CAAR, but there is difference in the current change between different couples; (5) The anodic dissolution rate of the magnesium alloy increases by 2-3 orders after being coupled with these four kinds of metals and the galvanic effects of these couples have such a relation as γH62>γ316LS.S>γLY12 >γA3.

  12. Sliding Wear Behavior of Plasma Sprayed Zirconia Coating on Cast Aluminum against Silicon Carbide Ceramic

    Institute of Scientific and Technical Information of China (English)

    Thuong-Hien LE; Young-Hun CHAE; Seock-Sam KIM

    2005-01-01

    The sliding wear behaviors of ZrO2-22 wt pct MgO (MZ) and ZrO2-8 wt pct Y2O3 (YZ) coatings deposited on a cast aluminum alloy with bond layer (NiCrCoAlY) by plasma spray were investigated under dry test conditions at room temperature. Under all load conditions, the wear mechanisms of the MZ and YZ coatings were almost the same.The material transfer and pullout were involved in the wear process of the studied coatings under the test conditions.The wear rate of the MZ coating was less than that of the YZ coating. While increasing the normal load, the wear rates of the MZ and YZ coatings increased. SEM was used to examine the worn surfaces and to elucidate likely wear mechanisms. Energy dispersive X-ray spectroscopy (EDX) analysis of the worn surfaces indicated that material transfer occurred in the direction from the SiC ball to the disk. Fracture toughness had a significant influence on the wear performance of the coatings. It was suggested that the material transfer played an important role in the wear behavior.

  13. Effect of Carbon Properties on Melting Behavior of Mold Fluxes for Continuous Casting of Steels

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    During continuous casting of steel, the properties of mold fluxes strongly affect the casting performance,steel quality and environment of casting operation. The high temperature microscopy technique was used to investigate the melting behaviour of mold fluxes, and drip test method was used to determine their melting rate. The results showed that free carbon is a dominant factor in governing the melting behaviour of fluxes, and the melting rate is increased with increasing carbon reactivity and decreasing carbon content.

  14. Differential expressions of nuclear proteomes between honeybee (Apis mellifera L.) Queen and Worker Larvae: a deep insight into caste pathway decisions.

    Science.gov (United States)

    Begna, Desalegn; Han, Bin; Feng, Mao; Fang, Yu; Li, Jianke

    2012-02-01

    Honeybees (Apis mellifera L.) possess individuals (castes) in their colonies, to which specific tasks are allocated. Owing to a difference in nutrition, the young female larvae develop into either a fertile queen or a sterile worker. Despite a series of investigations on the underlying mechanisms of honeybee caste polyphenism, information on proteins and enzymes involved in DNA and RNA regulation in the nucleus is still missing. The techniques of nuclear protein enrichment, two-dimensional electrophoresis, mass spectrometry and bioinformatics were applied to understand the nuclear proteome changes in response to changes in environmental settings (nutrition and time) during the early developmental stages at the third (72 h), fourth (96 h), and fifth (120 h) instars of the two caste intended larvae. A total of 120 differentially expressed nuclear proteins were identified in both caste intended larvae during these developmental stages. The third, fourth and fifth instars of queen prospective larvae expressed 69%, 84%, and 68% of the proteins that had altered expression, respectively. Particularly, the prospective queen larvae up-regulated most of the proteins with nuclear functions. In general, this changing nuclear proteome of the two caste intended larvae over the three developmental stages suggests variations in DNA and RNA regulating proteins and enzymes. These variations of proteins and enzymes involved in DNA and RNA regulation in response to differential nutrition between the two caste intended larvae lead the two caste larvae to pursue different developmental trajectories. Hence, this first data set of the nuclear proteome helps us to explore the innermost biological makings of queen and worker bee castes as early as before the 72 h (3rd instar). Also, it provides new insights into the honeybee's polymorphism at nuclear proteome level and paves new ways to understand mechanisms of caste decision in other eusocial insects.

  15. Hot tensile deformation behavior of twin roll casted 7075 aluminum alloy

    Science.gov (United States)

    Wang, Lei; Yu, Huashun; Lee, Yunsoo; Kim, Hyoung-Wook

    2015-09-01

    High temperature deformation behavior of the 7075 aluminum alloy sheets fabricated by twin roll casting and rolling was investigated by hot tensile tests at different temperatures from 350 to 500 °C and various initial strain rates from 1×10-3 to 1×10-2 s-1. The results show that flow stress increased with increasing initial strain rate and decreasing deformation temperature. A large elongation of 200% was obtained at relatively high strain rate of 5×10-3 s-1 at 450 °C. It is closely related with the grain boundary sliding at elevated temperature attributed to the recrystallized fine grains and the large volume fraction of high-angle grain boundaries. The fracture transformation mechanism changes from ductile transgranular fracture to ductile intergranular fracture due to the recrystallized fine grains at high temperature. High density and uniform cavities observed in large elongation samples at high temperature reveals the contribution of grain boundary sliding. Necking-controlled failure mode was characterized by rare cavities with low elongation.

  16. Casting fabrication of in situ Al3Ti-Al composites and their wear behaviors

    Institute of Scientific and Technical Information of China (English)

    Chen Tijun; Li Jian; Hao Yuan

    2009-01-01

    The Al3li intermetallic reinforced pure Al, Al-13Si and Al-17Cu matrix composites were prepared by casting method. Their microstructures and dry sliding wear behaviors at room temperature and 100℃ were particularly investigated. The results indicated that the Al3Ti phases in these composites were all in flaky form. But the aspect ratio of the Al3Ti platelets decreased with the increase of Ti content in the pure AI, Al-Cu and Al-Si matrix composites, in order of effectiveness. The effect of Si on the Al3Ti morphology seemed to be greater than that of Cu. The distributions of the Al3Ti platelets were different in the different matrix composites, leading to different grain refining effects. Except for the sub-wear regime of adhesive wear, the plastic deformation induced wear was a dominant wear mechanism for all of the composites at room temperature and 100℃. Increasing the testing temperature, decreasing the Al3Ti content or the hardness of materials could enhance these two wear mechanisms, and thus increase the wear rate. The Al-Cu matrix composite had the best wear resistance, while the pure Al matrix composite showed the worst for the same Ti content. These differences or changes were attributed to the differences in materials' hardness or the strengthening effects of the Al3Ti platelets.

  17. Effect of Scale Formation on Copper Enrichment Behavior in Continuously Cast Slab

    Institute of Scientific and Technical Information of China (English)

    Nan WANG; Jin XU; Shan YU; Guang-zong ZHANG; Guang-hao CHEN; Min CHEN

    2016-01-01

    Copper enrichment behavior in continuously cast slab induced by scale formation during continuous cooling was experimentally investigated,and the effects of initial slab surface temperature and oxygen potential in atmos-phere were discussed.The results showed that a loose scale adhered to the substrate was formed in H2 O-N2 atmos-phere at higher slab surface temperature compared to a gap formed between the scale and the steel substrate after continuous cooling in H2 O-O2-N2 atmosphere.Under the condition of continuous cooling in H2 O-N2 atmosphere, the copper enrichment occurred both within the loose scale and at the scale/steel interface with simultaneous Ni en-richment near the interface at higher slab surface temperature.The combined effects of the loose scale and nickel en-richment were thought to promote the back-migration of Cu-rich phase from the interface and occlusion within the scale layer.While in H2 O-O2-N2 atmosphere,the Cu enrichment was found on the steel side and the formed gap pre-vented the migration of Cu to the scale.

  18. Differential expression of hypoxia pathway genes in honey bee (Apis mellifera L.) caste development.

    Science.gov (United States)

    Azevedo, Sergio Vicente; Caranton, Omar Arvey Martinez; de Oliveira, Tatiane Lippi; Hartfelder, Klaus

    2011-01-01

    Diphenism in social bees is essentially contingent on nutrient-induced cellular and systemic physiological responses resulting in divergent gene expression patterns. Analyses of juvenile hormone (JH) titers and functional genomics assays of the insulin-insulin-like signaling (IIS) pathway and its associated branch, target-of-rapamycin (TOR), revealed systemic responses underlying honey bee (Apis mellifera) caste development. Nevertheless, little attention has been paid to cellular metabolic responses. Following up earlier investigations showing major caste differences in oxidative metabolism and mitochondrial physiology, we herein identified honey bee homologs of hypoxia signaling factors, HIFα/Sima, HIFβ/Tango and PHD/Fatiga and we investigated their transcript levels throughout critical stages of larval development. Amsima, Amtango and Amfatiga showed correlated transcriptional activity, with two peaks of occurring in both queens and workers, the first one shortly after the last larval molt and the second during the cocoon-spinning phase. Transcript levels for the three genes were consistently higher in workers. As there is no evidence for major microenvironmental differences in oxygen levels within the brood nest area, this appears to be an inherent caste character. Quantitative PCR analyses on worker brain, ovary, and leg imaginal discs showed that these tissues differ in transcript levels. Being a highly conserved pathway and linked to IIS/TOR, the hypoxia gene expression pattern seen in honey bee larvae denotes that the hypoxia pathway has undergone a transformation, at least during larval development, from a response to environmental oxygen concentrations to an endogenous regulatory factor in the diphenic development of honey bee larvae.

  19. Vitellogenin underwent subfunctionalization to acquire caste and behavioral specific expression in the harvester ant Pogonomyrmex barbatus.

    Science.gov (United States)

    Corona, Miguel; Libbrecht, Romain; Wurm, Yannick; Riba-Grognuz, Oksana; Studer, Romain A; Keller, Laurent

    2013-01-01

    The reproductive ground plan hypothesis (RGPH) proposes that the physiological pathways regulating reproduction were co-opted to regulate worker division of labor. Support for this hypothesis in honeybees is provided by studies demonstrating that the reproductive potential of workers, assessed by the levels of vitellogenin (Vg), is linked to task performance. Interestingly, contrary to honeybees that have a single Vg ortholog and potentially fertile nurses, the genome of the harvester ant Pogonomyrmex barbatus harbors two Vg genes (Pb_Vg1 and Pb_Vg2) and nurses produce infertile trophic eggs. P. barbatus, thus, provides a unique model to investigate whether Vg duplication in ants was followed by subfunctionalization to acquire reproductive and non-reproductive functions and whether Vg reproductive function was co-opted to regulate behavior in sterile workers. To investigate these questions, we compared the expression patterns of P. barbatus Vg genes and analyzed the phylogenetic relationships and molecular evolution of Vg genes in ants. qRT-PCRs revealed that Pb_Vg1 is more highly expressed in queens compared to workers and in nurses compared to foragers. By contrast, the level of expression of Pb_Vg2 was higher in foragers than in nurses and queens. Phylogenetic analyses show that a first duplication of the ancestral Vg gene occurred after the divergence between the poneroid and formicoid clades and subsequent duplications occurred in the lineages leading to Solenopsis invicta, Linepithema humile and Acromyrmex echinatior. The initial duplication resulted in two Vg gene subfamilies preferentially expressed in queens and nurses (subfamily A) or in foraging workers (subfamily B). Finally, molecular evolution analyses show that the subfamily A experienced positive selection, while the subfamily B showed overall relaxation of purifying selection. Our results suggest that in P. barbatus the Vg gene underwent subfunctionalization after duplication to acquire caste- and

  20. Effect of Rotational Speeds on the Cast Tube During Vertical Centrifugal Casting Process on Appearance, Microstructure, and Hardness Behavior for Al-2Si Alloy

    Science.gov (United States)

    Shailesh Rao, A.; Tattimani, Mahantesh S.; Rao, Shrikantha S.

    2015-04-01

    The flow of molten metal plays a crucial role in determining casting quality. During rotation of the mold, melt flow around its inner circumference determines the final configurations and properties of the cast tube. In this paper, Al-2Si alloy is cast in the vertical mold at the various rotational speeds of the mold. The uniform cylinder tube is formed at a rotational speed of 1000 rpm, while before and beyond this speed, irregular-shaped cast tube is formed. Finally, fine structured grain size with high hardness value is found in uniform cast tube compared with others.

  1. The effect of rules on differential reinforcement of other behavior.

    Science.gov (United States)

    Watts, Amanda C; Wilder, David A; Gregory, Meagan K; Leon, Yanerys; Ditzian, Kyle

    2013-01-01

    Previous research on the treatment of problem behavior has shown differential reinforcement of other behavior (DRO) to be an effective behavior-reduction procedure. However, the extent to which presession descriptions of the DRO contingency enhance intervention effects has not been examined. In the current study, we compared a condition in which a presession rule that described the DRO contingency was given to a condition in which no rule was given for 4 participants. The target behavior was toy play, which served as an analogue to problem behavior maintained by automatic reinforcement. Results showed that DRO was more efficient for 1 participant and more effective for 2 participants when a rule was given.

  2. Environmental fatigue behaviors of wrought and cast stainless steels in 310 .deg. C Deoxygenated Water

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Pyung Yeon

    2011-02-15

    Environmental fatigue behaviors of wrought type 316LN stainless steel and cast CF8M stainless steel were investigated. LCF tests were performed at fixed strain rate of 0.04%/s with 0.4%, 0.6%, 0.8%, 1.0% strain amplitudes in 310 .deg. C deoxygenated water environment. In addition, to analyze microstructure effect on fatigue behavior, low cycle fatigue tests in air environment were performed at fixed strain rate of 0.4%/s, 0.04%/s with 0.4%, 0.8% strain amplitudes. It was shown that the low cycle fatigue life of CF8M in a 310 .deg. C deoxygenated water environment was slightly longer than that of 316LN. On the other hand, the low cycle fatigue life of CF8M in a 310 .deg. C air environment was slightly shorter than that of 316LN or was similar with that of 316LN. Through OM observation and phase image analysis, it was confirmed that the ferrite content of CF8M tested in a 310 .deg. C deoxygenated water environment was larger than that of CF8M tested in a 310 .deg. C air environment. It was shown that the ferrite phase fraction of CF8M tested in 310 .deg. C deoxygenated water environment was approximately 26∼28% and that of CF8M tested in air environment was approximately 10∼12%. The difference of ferrite content in CF8M results in superior tensile properties as higher ferrite content. Furthermore, the difference of ferrite content in CF8M might be the cause of different result of fatigue life between CF8M and 316LN depending on environment. In this study, focused on CF8M having 26∼28% ferrite content, to understand the causes of these differences in a 310 .deg. C deoxygenated water environment, fracture surface and crack morphology were observed. And material factors like microstructure, mechanical properties factors like stress behavior during fatigue life, factors by environmentally assisted cracking (EAC) like hydrogen induced cracking (HIC) and chemical compositions of both materials were analyzed. Mainly in a 310 .deg. C deoxygenated water environment, the

  3. Influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence.

  4. Wear and Friction Behavior of Stir Cast Al-TiB2 Metal Matrix Composites with Various Lubricants

    Directory of Open Access Journals (Sweden)

    S. Poria

    2016-12-01

    Full Text Available Al- TiB2 metal matrix composites are fabricated using stir cast method and its tribological characterization is done using three different lubricants. Tribological studies are performed in a multi-tribotester using block-on-roller configuration under 25-75 N loads and 400-600 rpm rotational speeds. Four different weight percentages of TiB2 are considered in this study. Comparison between dry condition and lubricated conditions is gleaned to differentiate wear and friction characteristics and SEM images are taken to fortify them. Lubricated conditions yield large reduction in wear and friction compared to dry condition.

  5. Mechanical properties and constitutive behaviors of as-cast 7050 aluminum alloy from room temperature to above the solidus temperature

    Institute of Scientific and Technical Information of China (English)

    Qing-ling Bai; Hong-xiang Li; Qiang Du; Ji-shan Zhang; Lin-zhong Zhuang

    2016-01-01

    The mechanical properties and constitutive behaviors of as-cast AA7050 in both the solid and semi-solid states were determined using the on-cooling and in situ solidification approaches, respectively. The results show that the strength in the solid state tends to increase with decreasing temperature. The strain rate plays an important role in the stress–strain behaviors at higher temperatures, whereas the influ-ence becomes less pronounced and irregular when the temperature is less than 250°C. The experimental data were fitted to the extended Ludwik equation, which is suitable to describe the mechanical behavior of the materials in the as-cast state. In the semi-solid state, both the strength and ductility of the alloy are high near the solidus temperature and decrease drastically with decreasing solid fraction. As the solid fraction is less than 0.97, the maximum strength only slightly decreases, whereas the post-peak ductility begins to increase. The experimental data were fitted to the modified creep law, which is used to describe the mechanical behavior of semi-solid materials, to determine the equivalent parameter f GBWL, i.e., the fraction of grain boundaries covered by liquid phase.

  6. A coupled analysis of fluid flow, heat transfer and deformation behavior of solidifying shell in continuously cast beam blank

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Eui; Yeo, Tae Jung; Oh, Kyu Hwan; Yoon, Jong Kyu [School of Materials Science and Engineering, Seoul Nat`l Univ., Seoul (Korea, Republic of); Han, Heung Nam [Oxford Center for Advanced Materials and Composites, Department of Materials, Univ. of Oxford (United Kingdom)

    1997-12-31

    A mathematical model for a coupled analysis of fluid flow, heat transfer and deformation behavior in the continuously cast beam blank has been developed. The fluid flow, heat transfer and solidification in the mold region were analyzed with 3-dimensional finite difference method (FDM) based on control volume method. A body fitted coordinate system was introduced for the complex geometry of the beam blank. The effects of turbulence and natural convection of molten steel were taken into account in determining the fluid flow in the strand. The thermo-elasto-plastic deformation behavior in the cast strand and the formation of air gap between the solidifying shell and the mold were analyzed by the finite element method (FEM) using the 2-dimensional slice temperature profile calculated by the FDM. The heat flow between the strand and the mold was evaluated by the coupled analysis between the fluid flow-heat transfer analysis and the thermo-elasto-plastic stress analysis. In order to determine the solid fraction in the mushy zone, the microsegregation of solute element was assessed. The effects of fluid flow on the heat transfer, the solidification of steel and the distribution of shell thickness during the casting of the beam blank were simulated. The deformation behavior of the solidifying shell and the possibility of cracking of the strand were also investigated. The recirculating flows were developed in the regions of the web and the flange tip. The impinging of the inlet flow from the nozzle retarded the growing of solidifying shell in the regions of the fillet and the flange. The air gap between the strand and the mold was formed near the region of the corner of the flange tip. At the initial stage of casting, the probability of the surface cracking was high in the regions of the fillet and the flange tip. After the middle stage of casting, the internal cracking was predicted in the regions of the flange tip, and between the fillet and the flange tip. (author) 38

  7. Comparison of electrochemical behavior of cast and sintered CuAg4at.% alloy during thermomechanical treatment

    Directory of Open Access Journals (Sweden)

    Rajčić-Vujasinović Mirjana M.

    2013-01-01

    Full Text Available The paper presents comparison of electrochemical behavior of samples of CuAg4at.% alloy obtained by powder metallurgy method and the same alloy obtained by melting and casting during oxidation in an alkaline medium. Investigated alloy exhibits anneal hardening effect, so it was examined in each stage of thermomechanical treatment resulting in this effect. Cyclic voltammetry investigations show that both sintered and cast samples after cold rolling to final reduction of 60 % behave as completely homogenous phases. In that stage of thermomechanical treatment peaks corresponding to reactions on silver do not appear and currents on cyclic voltammograms are lowest. After annealing below the recrystallization temperature both samples exhibit anneal hardening; in this stage sintered alloy retains its corrosion stability, whereas current densities for the cast alloy increase and the peaks characteristic for silver appear again. Further annealing above the recrystallization temperature leads to the increasing of current density on voltammograms for samples obtained by both methods and all characteristic current peaks for silver reappear.

  8. Analysis of Solid-Liquid Interface Behavior during Continuous Strip-Casting Process Using Sharp-Interface Technique

    Directory of Open Access Journals (Sweden)

    Changbum Lee

    2013-01-01

    Full Text Available Continuous strip casting (CSC has been developed to fabricate thin metal plates while simultaneously controlling the microstructure of the product. A numerical analysis to understand the solid-liquid interface behaviors during CSC was carried out and used to identify the solidification morphologies of the plate, which were then used to obtain the optimum process conditions. In this study, we used a modified level contour reconstruction method and the sharp-interface method to modify the interface tracking, and we performed a simulation analysis to identify the differences in the material properties that affect the interface behavior. The effects of the process parameters such as the heat transfer coefficient and extrusion velocity on the behavior of the solid-liquid interface are estimated and also used to improve the CSC process.

  9. Hot ductility behavior of Incoloy 901 superalloy in the cast and wrought conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shore, Fatemeh Mohammadi; Morakabati, Maryam; Mahdavi, Rashid [AMR of Technology, Tehran (Iran, Islamic Republic of). Metallic Material Dept.

    2014-04-15

    Hot ductility was investigated in Incoloy 901 using hot tensile testing over a temperature range of 900 to 1200 C and at strain rates of 0.01 to 1 s{sup -1}, in the cast and wrought conditions. Maximum ductility was detected in the cast and wrought conditions at temperature ranges of 1000 to 1050 C and 1000 to 1100 C, respectively. More voids were seen at the fracture surface of the wrought specimens compared to the cast ones. At 950 C, the formation of large and non-homogeneous voids at the fracture surface, as well as the appearance of transgranular and intergranular cracks in the wrought specimen, support moderate ductility of the alloy. Microstructural analysis does not support the occurrence of dynamic recrystallization in the cast specimens. In contrast, dynamic recrystallization in the wrought specimens at the region of maximum hot ductility promoted diffusion, leading to ductile fracture. At temperatures higher than the maximum ductility range, the formation of intergranular cracks resulted in a remarkable decline in ductility. (orig.)

  10. 蜜蜂级型分化研究的进展%Research Progress on the Caste Differentiation in the Honeybee

    Institute of Scientific and Technical Information of China (English)

    沈芳; 殷玲; 刘振国; 沈杰; 吉挺

    2013-01-01

    Caste differentiation is the foundation of researches on bee eusocial biology. This review focuses on research progresses of bee caste differentiation, the contribution of nutrition, hormones, DNA methylation, differential expressed proteomics and genomics, cell size and histone deacetylase inhibitor activity to bee caste differentiation, and the interactions of those factors. Accordingly, the problems in recent researches and prospects for future researches on bee caste differentiation were put forward.%级型分化是蜜蜂生物学研究的基础。本研究总结了前人在蜜蜂级型分化的研究进展:营养与级型分化的关系;激素与级型分化的关系;DNA甲基化与级型分化的关系;基因组和蛋白质组的差异表达与级型分化的关系;蜂房大小和组蛋白去乙酰酶与级型分化的关系。这些研究结果表明:蜜蜂的级型分化的调节是一个非常复杂的过程,是很多因素共同调节的结果。据此提出关于蜜蜂级型分化研究存在的一些问题,并对以后的研究进行了展望。

  11. Effect of heat treatment on corrosion behavior of low pressure sand cast Mg-10Gd-3Y-0.5Zr alloys

    Institute of Scientific and Technical Information of China (English)

    Qian-qian Wu; Guang-ling Wei; Guo-hua Wu; Wen-cai Liu; Tian-peng Xuan; Wen-jiang Ding

    2016-01-01

    The corrosion behaviors of low-pressure sand cast Mg-10Gd-3Y-0.5Zr (wt.%) aloys in as-cast, solution treated (T4) and aged (T6) conditions were studied by means of immersion test and electrochemical measurements in 5wt.% NaCl solution saturated with Mg(OH)2. It was observed that the corrosion rate in the T4 condition was lower than that of the as-cast and T6 conditions by both sand casting and permanent mold casting with the same order of as-cast>T6>T4; while the corrosion resistance of the permanent mold casting is superior to the sand casting. The morphologies of the corrosion products are similar porous structures consisting of tiny erect lfakes perpendicular to the corroded surface of the aloy, irrespective of the heat treatment conditions. Especialy, the corrosion iflm in T4 condition is more compact than that in the other two conditions. In addition, the severer corrosion happening to the as-cast condition is correlated with the galvanic corrosion between the matrix and the eutectic compounds; while improved corrosion resistance for the T4 and T6 conditions is ascribed to the dissolution of the secondary eutectic compounds. The measured corrosion current densities of Mg-10Gd-3Y-0.5Zr aloys in as-cast, T4, and T6 conditions are 36 μA·cm-2, 10 μA·cm-2, and 33 μA·cm-2, respectively. The proposed equivalent circuit [Rs(CPE1(Rt(RfCPE2))] by Zview software matches wel with the tested electrochemical impedance spectra (EIS) data.

  12. Effect of heat treatment on corrosion behavior of low pressure sand cast Mg-10Gd-3Y-0.5Zr alloys

    Directory of Open Access Journals (Sweden)

    Qian-qian Wu

    2016-07-01

    Full Text Available The corrosion behaviors of low-pressure sand cast Mg-10Gd-3Y-0.5Zr (wt.% alloys in as-cast, solution treated (T4 and aged (T6 conditions were studied by means of immersion test and electrochemical measurements in 5wt.% NaCl solution saturated with Mg(OH2. It was observed that the corrosion rate in the T4 condition was lower than that of the as-cast and T6 conditions by both sand casting and permanent mold casting with the same order of as-cast>T6>T4; while the corrosion resistance of the permanent mold casting is superior to the sand casting. The morphologies of the corrosion products are similar porous structures consisting of tiny erect flakes perpendicular to the corroded surface of the alloy, irrespective of the heat treatment conditions. Especially, the corrosion film in T4 condition is more compact than that in the other two conditions. In addition, the severer corrosion happening to the as-cast condition is correlated with the galvanic corrosion between the matrix and the eutectic compounds; while improved corrosion resistance for the T4 and T6 conditions is ascribed to the dissolution of the secondary eutectic compounds. The measured corrosion current densities of Mg-10Gd-3Y-0.5Zr alloys in as-cast, T4, and T6 conditions are 36 μA·cm-2, 10 μA·cm-2, and 33 μA·cm-2, respectively. The proposed equivalent circuit [Rs(CPE1(Rt(RfCPE2] by Zview software matches well with the tested electrochemical impedance spectra (EIS data.

  13. An investigation of fracture and fatigue crack growth behavior of cast niobium aluminide intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Ye, F.; Soboyejo, W.O. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Farkas, D. [Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, 213 Holden Hall, Blacksburg, VA 24061-0237 (United States)

    1999-05-31

    This paper presents the results of a combined experimental and theoretical study of fracture toughness and fatigue crack growth in cast Nb-15Al-xTi (x=10, 25 and 40 at%) niobium aluminide-based intermetallics. Fracture toughness and fatigue crack growth resistance are shown to improve significantly in the cast alloy containing 40 at% Ti. The improvements in the fracture toughness of the 40Ti alloy are shown to be due to the combined effects of ligament toughening, crack-tip plasticity and crack-tip blunting. The atomistic simulations show that the increased plasticity in these alloys is associated with their higher Ti content. The micromechanisms of fatigue crack growth are also elucidated. The implications of the results are discussed for potential structural application of niobium aluminide intermetallics. (orig.) 19 refs.

  14. Study on fragmentation and dissolution behavior of carbide in a hot-rolled hypereutectic high chromium cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fei; Jiang, Yehua, E-mail: jiangyehua@kmust.edu.cn; Xiao, Han; Tan, Jun

    2015-01-05

    Highlights: • The method to prepare Carbon steel/High chromium iron is totally new. • High chromium iron can achieve small plastic deformation during hot rolling process. • Carbides in high chromium irons are crushed, refined obviously and becoming isolated, which is benefit to improve the impact toughness. • The carbide fragmentation and dissolution behavior of the hot-rolled HCCI were analyzed. - Abstract: A sandwich-structured composite containing a hypereutectic high chromium cast iron (HCCI) and low carbon steel (LCS) claddings was newly fabricated by centrifugal casting, then the blank was hot-rolled into composite plate. The carbide fragmentation and dissolution behavior of the hot-rolled HCCI were analyzed. During hot rolling, significant refinement of carbides was discovered in hot-rolled HCCI specimens. The carbides were broken and partly dissolved into the austenite matrix. The results show that carbides are firstly dissolved under the action of stress. There are grooves appeared at the boundaries of the carbides. The grooves reduce the cross section of the carbide. When the cross section of the carbide reaches to the required minimum critical cross section, the carbide breaks through the tensile force. After break, carbides continue to dissolve since more interfaces between the matrix and carbides are generated. The secondary carbides precipitated due to the dissolution are index as fcc and stacking faults parallel to the {1 1 1} are observed.

  15. Analytical Evaluation of Reinforced Concrete Pier and Cast-in-Steel-Shell Pile Connection Behavior considering Steel-Concrete Interface

    Directory of Open Access Journals (Sweden)

    Jiho Moon

    2016-01-01

    Full Text Available The seismic design of bridges may require a large-diameter deep pile foundation such as a cast-in-steel-shell (CISS pile where a reinforced concrete (RC member is cast in a steel casing. In practice, the steel casing is not considered in the structural design and the pile is assumed to be an RC member. It is partially attributed to the difficulties in evaluation of composite action of a CISS pile. However, by considering benefits provided by composite action of the infilled concrete and the steel casing, both the cost and size of CISS pile can be reduced. In this study, the structural behavior of the RC pier and the CISS pile connection is simulated by using an advanced 3D finite element (FE method, where the interface between the steel and concrete is also modeled. Firstly, the FE model is verified. Then, the parametric study is conducted. The analysis results suggest that the embedment length and the friction coefficient between the steel casing and the infilled concrete affect the structural behavior of the RC pier. Finally, the minimum embedment length with reference to the AASHTO design guideline is suggested considering the composite action of the CISS pile.

  16. Mechanical Properties and Corrosion-Abrasion Wear Behavior of Low-Alloy MnSiCrB Cast Steels Containing Cu

    Science.gov (United States)

    Luo, Kaishuang; Bai, Bingzhe

    2011-01-01

    Two medium carbon low-alloy MnSiCrB cast steels containing different Cu contents (0.01 wt pct and 0.62 wt pct) were designed, and the effect of Cu on the mechanical properties and corrosion-abrasion wear behavior of the cast steels was studied. The results showed that the low-alloy MnSiCrB cast steels obtained excellent hardenability by a cheap alloying scheme. The microstructure of the MnSiCrB cast steels after water quenching from 1123 K (850 °C) consists of lath martensite and retained austenite. After tempering at 503 K (230 °C), carbides precipitated, and the hardness of the cast steels reached 51 to 52 HRC. The addition of Cu was detrimental to the ductility and impact toughness but was beneficial to the wear resistance in a corrosion-abrasion wear test. The MnSiCrB cast steel with Cu by the simple alloying scheme and heat treatment has the advantages of being high performance, low cost, and environmentally friendly. It is a potential, advanced wear-resistant cast steel for corrosion-abrasion wear conditions.

  17. Microstructure and Mechanical Behavior of Squeeze Cast SiCw/AZ91 Magnesium Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The interfacial microstructure and tensile properties of the squeeze cast SiCw/AZ91 Mg composites were characterized. There exist uniform, fine and discrete MgO particles at the interface between SiC whisker and magnesium in the composites using acid aluminum phosphate binder. The interfacial reaction products MgO are beneficial to interfacial bonding between SiCw and the Mg matrix, resulting in an improvement of the mechanical properties of the composite.

  18. Dimorphic ovary differentiation in honeybee (Apis mellifera larvae involves caste-specific expression of homologs of ark and buffy cell death genes.

    Directory of Open Access Journals (Sweden)

    Rodrigo Pires Dallacqua

    Full Text Available The establishment of the number of repeated structural units, the ovarioles, in the ovaries is one of the critical events that shape caste polyphenism in social insects. In early postembryonic development, honeybee (Apis mellifera larvae have a pair of ovaries, each one consisting of almost two hundred ovariole primordia. While practically all these ovarioles continue developing in queen-destined larvae, they undergo massive programmed cell death (PCD in worker-destined larvae. So as to gain insight into the molecular basis of this fundamental process in caste differentiation we used quantitative PCR (qPCR and fluorescent in situ hybridization (FISH to investigate the expression of the Amark and Ambuffy genes in the ovaries of the two honeybee castes throughout the fifth larval instar. These are the homologs of ark and buffy Drosophila melanogaster genes, respectively, involved in activating and inhibiting PCD. Caste-specific expression patterns were found during this time-window defining ovariole number. Amark transcript levels were increased when ovariole resorption was intensified in workers, but remained at low levels in queen ovaries. The transcripts were mainly localized at the apical end of all the worker ovarioles, but appeared in only a few queen ovarioles, thus strongly suggesting a function in mediating massive ovariolar cell death in worker larvae. Ambuffy was mainly expressed in the peritoneal sheath cells covering each ovariole. The levels of Ambuffy transcripts increased earlier in the developing ovaries of queens than in workers. Consistent with a protective role against cell death, Ambuffy transcripts were localized in practically all queen ovarioles, but only in few worker ovarioles. The results are indicative of a functional relationship between the expression of evolutionary conserved cell death genes and the morphological events leading to caste-specific ovary differentiation in a social insect.

  19. Dimorphic ovary differentiation in honeybee (Apis mellifera) larvae involves caste-specific expression of homologs of ark and buffy cell death genes.

    Science.gov (United States)

    Dallacqua, Rodrigo Pires; Bitondi, Márcia Maria Gentile

    2014-01-01

    The establishment of the number of repeated structural units, the ovarioles, in the ovaries is one of the critical events that shape caste polyphenism in social insects. In early postembryonic development, honeybee (Apis mellifera) larvae have a pair of ovaries, each one consisting of almost two hundred ovariole primordia. While practically all these ovarioles continue developing in queen-destined larvae, they undergo massive programmed cell death (PCD) in worker-destined larvae. So as to gain insight into the molecular basis of this fundamental process in caste differentiation we used quantitative PCR (qPCR) and fluorescent in situ hybridization (FISH) to investigate the expression of the Amark and Ambuffy genes in the ovaries of the two honeybee castes throughout the fifth larval instar. These are the homologs of ark and buffy Drosophila melanogaster genes, respectively, involved in activating and inhibiting PCD. Caste-specific expression patterns were found during this time-window defining ovariole number. Amark transcript levels were increased when ovariole resorption was intensified in workers, but remained at low levels in queen ovaries. The transcripts were mainly localized at the apical end of all the worker ovarioles, but appeared in only a few queen ovarioles, thus strongly suggesting a function in mediating massive ovariolar cell death in worker larvae. Ambuffy was mainly expressed in the peritoneal sheath cells covering each ovariole. The levels of Ambuffy transcripts increased earlier in the developing ovaries of queens than in workers. Consistent with a protective role against cell death, Ambuffy transcripts were localized in practically all queen ovarioles, but only in few worker ovarioles. The results are indicative of a functional relationship between the expression of evolutionary conserved cell death genes and the morphological events leading to caste-specific ovary differentiation in a social insect.

  20. Behavioral Differentiation and Ovarian Development of Unmated Gynes, Queens, and Workers of Ectatomma vizottoi Almeida 1987 (Formicidae, Ectatomminae

    Directory of Open Access Journals (Sweden)

    Alexsandro Santana Vieira

    2012-01-01

    Full Text Available Behavioral differentiation and ovarian development of unmated gynes, queens, and workers of Ectatomma vizottoi were investigated in laboratory conditions. Forty-one behavioral acts were identified and quantified for workers, 19 for queens and 24 for unmated gynes, for an overall species repertoire of 42 different behavioral acts. Ovipositing reproductive eggs was an exclusive task of the queen, whereas workers showed 15 caste-specific behaviors. The most important (frequent behaviors for the queens were brood care, immobility, and reproduction, and for workers were immobility, grooming/interaction, brood care, and foraging. Unmated gynes (not winged primarily showed immobility, brood care, grooming/interaction, and foraging. Analysis of ovarian development showed that unmated gynes had little-developed ovarioles, in contrast to queens. Queens and unmated gynes showed a clear behavioral differentiation, in which queens played the role of reproducers and unmated gynes performed activities belonging to the worker repertoire. Despite the presence of several breeding queens in the colony, functional monogyny was the rule.

  1. Temperature effects on the static and dynamic fracture behaviors of low-silicon CA-15 tempered stainless steel castings

    Science.gov (United States)

    Hsu, Cheng-Hsun; Teng, Hwei-Yuan

    2005-04-01

    In this research we studied the effect of testing temperature on both static and dynamic fracturing behaviors of low-silicon CA-15 martensitic stainless steel (MSS) castings after austenitizing and tempering treatments. The results showed that the material's microstructure was influenced by heat treatment and various testing temperatures would cause different fracturing mechanisms. In static tensile tests, the 573-673 K tempered specimens occurred secondary strengthening at 423 K and 298 K testing temperatures. However, there is a contrast of weakening occurred at 123 K for the same type of tempered samples. The phenomenon was mainly triggered by local cracking at the ferrite/martensitic interface and incoherent precipitate site in the materials because of the existence of shrinkage stress under subzero temperature. In the dynamic strain-rate tests, impact embrittlement occurred in the 573-673 K tempered samples as a result of the tempered martensite embrittlement (TME) phenomenon. The ductile-to-brittle transition temperature (DBTT) of the tempered material was obviously lower than that of the as-cast material. Also, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to correlate the properties attained to the microstructural observation.

  2. Effects of Strain Ratio on Fatigue Behavior of G20Mn5QT Cast Steel

    Institute of Scientific and Technical Information of China (English)

    韩庆华; 郭琪; 尹越; 邢颖

    2016-01-01

    Due to traffic and wave actions, cast steel joints are subjected to variable-amplitude fatigue loading, which may cause fatigue problems. The ratio of the minimum strain to the maximum strain(strain ratio)can be em-ployed to analyze the influence of variable-amplitude fatigue both in the elastic and plastic ranges. To evaluate the effect of the strain ratio on G20Mn5QT cast steel, the fatigue tests of smooth specimens were carried out at the strain ratio of 0.1. The cyclic deformation and the relationships between the strain amplitude, the stress amplitude, the Smith, Watson and Topper(SWT)parameter and fatigue life were studied and compared with those at the strain ratio of-1. Compared with other methods, Basquin formula and Solonberg formula provide reliable and appropri-ate ranges ofS-N curve and fatigue limit at different strain ratios respectively. The SWT parameter can be used to predict the fatigue life at other strain ratios accurately.

  3. Effects of the Argil on Sintering Behavior of the Coating for Evaporated Pattern Casting (EPC) Cast Steel%陶土对铸钢消失模涂料烧结性的影响

    Institute of Scientific and Technical Information of China (English)

    潘强; 袁子洲; 车少波; 王丰; 范金虎

    2012-01-01

    Archimedes method was used to test the density of sintered samples, and the effects of the argil on sintering behavior of the coating for evaporated pattern casting (EPC) cast steel were investigated through measuring density of sintered samples by Archimedes method. The results show that with increasing in the argil content and in the sintering temperature, the volume density of the samples is increased. The volume density of the sample is increased significantly with 5% argil content at 1 550 °C , meeting the requirements of the coating for evaporated pattern casting cast steel. The practical pouring experiment was conducted to verify the coating behavior. The coating layer cross-section was observed by scanning electron microscope (SEM). The results reveal that good sintering layer contacting with steel sintered can be observed, where refractory is aggregated into a whole piece to prevent the further penetration of molten steel, so that the coating easily stripped from the casting surface automatically.%采用阿基米德法测试烧结试样密度,研究了陶土对铸钢消失模涂料烧结性的影响.结果表明,随着陶土含量和烧结温度的增加,试样体积密度都有增大趋势.陶土含量为5%时,试样在1 550℃时密度显著增大,符合铸钢消失模涂料要求.另外,进行现场浇注试验,对涂片层断面进行扫描电镜分析,涂片层断面与钢水接触部分烧结良好,耐火骨料连成整片,阻止钢水进一步渗透,使涂料烧结壳从铸件表面自动剥离.

  4. Differential reinforcement of other behavior (DRO) to reduce aggressive behavior following traumatic brain injury.

    Science.gov (United States)

    Hegel, M T; Ferguson, R J

    2000-01-01

    Severe brain injury can result in significant neurobehavioral and social functioning impairment. In rehabilitation settings, behavioral problems of aggression and nonadherence to therapeutic activities can pose barriers to maximal recovery of function. Behavioral interventions seem to be effective in reducing problem behavior among individuals recovering from severe brain trauma, but well-controlled studies examining the efficacy of such interventions are sparse. This article presents a single-case, multiple-baseline study of a differential reinforcement of other behavior (DRO) procedure in a 28-year-old, brain-injured male with aggressive behavior problems. The procedure successfully reduced the frequency of problem behavior by up to 74%, maintained at 1-month follow-up. Implications of this intervention for individuals with brain injury are discussed, and testing of this procedure using a between-group design seems indicated.

  5. Microstructure and damping behavior of SiCp/Gr/2024Al metal matrix composites by squeeze casting technology

    Institute of Scientific and Technical Information of China (English)

    LENG Jin-feng; WU Gao-hui

    2006-01-01

    SiCp/Gr/2024Al metal matrix composites were processed by squeeze casting technology. The microstructure of composites was observed by SEM and TEM, and the effects of graphite particulates and SiC particulates on the damping behaviors of composites were also investigated. The results show that the microstructure of composites was dense and homogeneous, without any interfacial reactivity among reinforcement/matrix interfaces. Compared with the damping capacity of 2024Al, the damping capacity of composites was enhanced significantly by addition of SiC or graphite particulates. The main damping mechanisms of SiCp/Al composites were ascribed to the dislocation damping, and those of SiCp/Gr/2024Al were attributed to the intrinsic damping and interface damping.

  6. Densification behavior, doping profile and planar waveguide laser performance of the tape casting YAG/Nd:YAG/YAG ceramics

    Science.gov (United States)

    Ge, Lin; Li, Jiang; Qu, Haiyun; Wang, Juntao; Liu, Jiao; Dai, Jiawei; Zhou, Zhiwei; Liu, Binglong; Kou, Huamin; Shi, Yun; Wang, Zheng; Pan, Yubai; Gao, Qingsong; Guo, Jingkun

    2016-10-01

    The sintering behavior and doping concentration profile of the planar waveguide YAG/Nd:YAG/YAG ceramics by the tape casting and solid-state reaction method were investigated on the basis of densification trajectory, microstructure evolution, and Nd3+ ions diffusion. The porosity of the green body by tape casting and cold isostatic pressing is about 38.6%. And the green bodies were consolidated from 1100 °C to 1800 °C for 0.5-20 h to study the densification and the doping diffusion behaviors. At the temperature higher than 1500 °C, pure YAG phase is formed, followed by the densification and grain growth process. With the increase of temperature, two sintering stages occur, corresponding to remarkable densification and significant grain growth, respectively. The mechanism controlling densification at 1550 °C is grain boundary diffusion. The diffusion of Nd3+ ions is more sensitive to temperature than the sintering time, and the minimum temperature required for the obvious diffusion of Nd3+ ions is higher than 1700 °C. Finally, planar waveguide YAG/1.5 at.%Nd:YAG/YAG transparent ceramics with in-line transmittance of 84.8% at 1064 nm were obtained by vacuum-sintering at 1780 °C for 30 h. The fluorescence lifetime of 4F3/2 state of Nd3+ in the specimen is about 259 μs. The prepared ceramic waveguide was tested in a laser amplifier and the laser pulse was amplificated from 87 mJ to 238 mJ, with the pump energy of 680 mJ.

  7. Low Cycle Fatigue Behavior of HT250 Gray Cast Iron for Engine Cylinder Blocks

    Science.gov (United States)

    Fan, K. L.; He, G. Q.; She, M.; Liu, X. S.; Yang, Y.; Lu, Q.; shen, Y.; Tian, D. D.

    2014-08-01

    The strain-controlled low cycle fatigue properties were evaluated on specimens of HT250 gray cast iron (GCI) at room temperature. The material exhibited cyclic stabilization at a low strain amplitude of 0.1% and cyclic softening characteristic at higher strain amplitudes (0.15-0.30%). At a representative total strain amplitude (0.30%), the hysteresis loops of HT250 GCI were asymmetric with a large amount of plastic deformation in the compressive phases. Furthermore, the hysteresis loop became larger in both width and height with increasing total strain amplitude (from 0.10 to 0.30%), and tended to exhibit a clockwise rotation. The fatigue crack propagation mechanisms were different at various total strain amplitudes, where high stress concentration due to dislocation pile-up favored fatigue crack initiation in the examined HT250. Finally, the roughness-induced crack closure was a key to determine the crack growth rate as well as fatigue life.

  8. Optimal Control Method of Parabolic Partial Differential Equations and Its Application to Heat Transfer Model in Continuous Cast Secondary Cooling Zone

    Directory of Open Access Journals (Sweden)

    Yuan Wang

    2015-01-01

    Full Text Available Our work is devoted to a class of optimal control problems of parabolic partial differential equations. Because of the partial differential equations constraints, it is rather difficult to solve the optimization problem. The gradient of the cost function can be found by the adjoint problem approach. Based on the adjoint problem approach, the gradient of cost function is proved to be Lipschitz continuous. An improved conjugate method is applied to solve this optimization problem and this algorithm is proved to be convergent. This method is applied to set-point values in continuous cast secondary cooling zone. Based on the real data in a plant, the simulation experiments show that the method can ensure the steel billet quality. From these experiment results, it is concluded that the improved conjugate gradient algorithm is convergent and the method is effective in optimal control problem of partial differential equations.

  9. The skin effect and the yielding behavior of cold chamber high pressure die cast Mg-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, K. Vanna [ARC Centre of Excellence for Design in Light Metals, Materials Engineering School of Engineering, University of Queensland, Brisbane, QLD, 4072 (Australia); Caceres, C.H., E-mail: c.caceres@uq.edu.au [ARC Centre of Excellence for Design in Light Metals, Materials Engineering School of Engineering, University of Queensland, Brisbane, QLD, 4072 (Australia); Nagasekhar, A.V. [ARC Centre of Excellence for Design in Light Metals, Materials Engineering School of Engineering, University of Queensland, Brisbane, QLD, 4072 (Australia); Easton, M.A. [CAST Co-operative Research Centre, Department of Materials Engineering Monash University, Melbourne, VIC, 3800 (Australia)

    2012-04-30

    Highlights: Black-Right-Pointing-Pointer The area fraction of elastic skin was calculated for a range of Mg-Al alloys. Black-Right-Pointing-Pointer The skin was defined using micro mechanistic concepts and tensile testing data. Black-Right-Pointing-Pointer The elastic constraint imposed by the skin on the core is discussed. Black-Right-Pointing-Pointer The skin covers {approx}30% of the cross section of the most concentrated alloy. - Abstract: The volume fraction of material that remained elastic as yielding developed in cast-to-shape tensile specimens of binary alloys with Al contents between 0.47 and 11.6 mass% was calculated using the Kocks-Mecking method of analysis. In the most dilute alloys the elastic fraction decreased rapidly to zero at a well-defined stress, suggesting that yielding was uniform across the specimen, whereas in the concentrated ones it decreased gradually over a wide range of stresses, suggesting that yielding developed first in the softer core of the casting while the harder outer layer, or skin, remained elastic. Comparison with specimens of the concentrated alloys which had a surface layer removed showed that the strain hardening behavior of the core resembled that of full specimens of the most dilute alloy. The maximum amount of elastic material in comparison with the most dilute alloy was used to define the area fraction covered by the skin, for each alloy. The skin covered between {approx}10% and {approx}30% of the cross section, the greater values for the concentrated alloys. The skin imposed an elastic constraint that delayed the development of full plasticity at the core.

  10. A Comparison of Response Cost and Differential Reinforcement of Other Behavior to Reduce Disruptive Behavior in a Preschool Classroom

    Science.gov (United States)

    Conyers, Carole; Miltenberger, Raymond; Maki, Amber; Barenz, Rebecca; Jurgens, Mandy; Sailer, Angela; Haugen, Meredith; Kopp, Brandon

    2004-01-01

    This study investigated the effectiveness of response cost and differential reinforcement of other behavior (DRO) in reducing the disruptive behaviors of 25 children in a preschool classroom. Using an alternating treatments design, disruptive behavior was reduced when the participants earned tokens for the absence of disruptive behavior (DRO) or…

  11. A comparison of response cost and differential reinforcement of other behavior to reduce disruptive behavior in a preschool classroom.

    Science.gov (United States)

    Conyers, Carole; Miltenberger, Raymond; Maki, Amber; Barenz, Rebecca; Jurgens, Mandy; Sailer, Angela; Haugen, Meredith; Kopp, Brandon

    2004-01-01

    This study investigated the effectiveness of response cost and differential reinforcement of other behavior (DRO) in reducing the disruptive behaviors of 25 children in a preschool classroom. Using an alternating treatments design, disruptive behavior was reduced when the participants earned tokens for the absence of disruptive behavior (DRO) or lost tokens for the occurrence of disruptive behavior (response cost). Initially, DRO was more successful in reducing the number of disruptive behaviors; however, over time, response cost proved to be more effective.

  12. Comprehensive behavioral analysis of cluster of differentiation 47 knockout mice.

    Directory of Open Access Journals (Sweden)

    Hisatsugu Koshimizu

    Full Text Available Cluster of differentiation 47 (CD47 is a member of the immunoglobulin superfamily which functions as a ligand for the extracellular region of signal regulatory protein α (SIRPα, a protein which is abundantly expressed in the brain. Previous studies, including ours, have demonstrated that both CD47 and SIRPα fulfill various functions in the central nervous system (CNS, such as the modulation of synaptic transmission and neuronal cell survival. We previously reported that CD47 is involved in the regulation of depression-like behavior of mice in the forced swim test through its modulation of tyrosine phosphorylation of SIRPα. However, other potential behavioral functions of CD47 remain largely unknown. In this study, in an effort to further investigate functional roles of CD47 in the CNS, CD47 knockout (KO mice and their wild-type littermates were subjected to a battery of behavioral tests. CD47 KO mice displayed decreased prepulse inhibition, while the startle response did not differ between genotypes. The mutants exhibited slightly but significantly decreased sociability and social novelty preference in Crawley's three-chamber social approach test, whereas in social interaction tests in which experimental and stimulus mice have direct contact with each other in a freely moving setting in a novel environment or home cage, there were no significant differences between the genotypes. While previous studies suggested that CD47 regulates fear memory in the inhibitory avoidance test in rodents, our CD47 KO mice exhibited normal fear and spatial memory in the fear conditioning and the Barnes maze tests, respectively. These findings suggest that CD47 is potentially involved in the regulation of sensorimotor gating and social behavior in mice.

  13. Monotonic and cyclic deformation behavior of MIG-CMT welded and heat-treated joints of aluminum cast and wrought alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kantehm, Matthias; Soeker, Marcus; Krupp, Ulrich; Michels, Wilhelm [Faculty of Engineering and Computer Science, Institute of Materials Design and Structural Integrity, University of Applied Sciences Osnabrueck, 49009 Osnabrueck (Germany)

    2012-10-15

    While the fatigue behavior of die cast aluminum as well as welded aluminum wrought alloys have been subject of several studies, no systematic work has been carried out on hybrid structures made as a combination of welded sand castings and wrought alloys. Aim of the present study is to correlate the monotonic and cyclic deformation behavior of thin sheet welded joints with the microstructure in the heat affected zone of the material combination sand cast EN AC-Al Si7Mg0.3 and wrought alloy EN AW-Al Si1MgMn (EN AW-6082). The metal sheets were welded using a metal inert gas cold metal transfer process under variation of the welding gap, the heat treatment parameters, as well as the surface finishes. It was demonstrated by Woehler diagrams based on bending fatigue tests that the fatigue life could be increased for the welded and heat treated specimens as compared to the as-received cast specimens. By means of optical microscopy this effect was attributed to microstructural changes due to the optimized welding and heat treatment process. A detailed analysis of the mechanical tests was possible by the application of an optical 3D strain analysis. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Modeling of the interface behavior in tape casting of functionally graded ceramics for magnetic refrigeration parts

    DEFF Research Database (Denmark)

    Jabbari, Masoud; Spangenberg, Jon; Hattel, Jesper Henri

    2013-01-01

    of a graded configuration of the magnetocaloric materials. The Newtonian flow behavior with relatively high viscosity is assumed for each fluid and used in the simulation with a commercial CFD code (ANSYS FLUENT). The results show that the density difference does not affect the interface between the adjacent...

  15. Polarization-corrosion behavior of commercial gold- and silver-base casting alloys in Fusayama solution.

    Science.gov (United States)

    Johnson, D L; Rinne, V W; Bleich, L L

    1983-12-01

    Based on polarization measurements, high Au alloys are highly corrosion-resistant and exhibit the lowest corrosion rates; intermediate Au, Ag, and Pd alloys with Cu are passive but exhibit higher corrosion rates. Twenty weight percent (w/o) In-Ag alloys exhibit active corrosion behavior at potentials only 100 mV noble to the corrosion potential.

  16. A Comparison of Function-Based Differential Reinforcement Interventions for Children Engaging in Disruptive Classroom Behavior

    Science.gov (United States)

    LeGray, Matthew W.; Dufrene, Brad A.; Sterling-Turner, Heather; Olmi, D. Joe; Bellone, Katherine

    2010-01-01

    This study provides a direct comparison of differential reinforcement of other behavior (DRO) and differential reinforcement of alternative behavior (DRA). Participants included three children in center-based classrooms referred for functional assessments due to disruptive classroom behavior. Functional assessments included interviews and brief…

  17. O on the Crystallization Behavior of Lime-Alumina-Based Mold Flux for Casting High-Al Steels

    Science.gov (United States)

    Lu, Boxun; Chen, Kun; Wang, Wanlin; Jiang, Binbin

    2014-08-01

    With the development of advanced high strength steel (AHSS), a large amount of aluminum was added into steels. The reaction between aluminum in the molten steel and silica based mold flux in the continuous-casting process would tend to cause a series of problems and influence the quality of slabs. To solve the above problems caused by the slag-steel reaction, nonreactive lime-alumina-based mold flux system has been proposed. In this article, the effect of Li2O and Na2O on the crystallization behavior of the lime-alumina-silica-based mold flux has been studied by using the single hot thermocouple technology (SHTT) and double hot thermocouple technology (DHTT). The results indicated that Li2O and Na2O in the above mold flux system play different roles as they behaved in traditional lime-silica based mold flux, which would tend to inhibit general mold flux crystallization by lowering the initial crystallization temperature and increasing incubation time, especially in the high-temperature region. However, when their content exceeds a critical value, the crystallization process of mold fluxes in low temperature zone would be greatly accelerated by the new phase formation of LiAlO2 and Na x Al y Si z O4 crystals, respectively. The crystalline phases precipitated in all samples during the experiments are discussed in the article.

  18. A comparison of response cost and differential reinforcement of other behavior to reduce disruptive behavior in a preschool classroom.

    OpenAIRE

    Conyers, Carole; Miltenberger, Raymond; Maki, Amber; Barenz, Rebecca; Jurgens, Mandy; Sailer, Angela; Haugen, Meredith; Kopp, Brandon

    2004-01-01

    This study investigated the effectiveness of response cost and differential reinforcement of other behavior (DRO) in reducing the disruptive behaviors of 25 children in a preschool classroom. Using an alternating treatments design, disruptive behavior was reduced when the participants earned tokens for the absence of disruptive behavior (DRO) or lost tokens for the occurrence of disruptive behavior (response cost). Initially, DRO was more successful in reducing the number of disruptive behavi...

  19. Thermomechanical behavior of dry contacts in disc brake rotor with a grey cast iron composition

    Directory of Open Access Journals (Sweden)

    Belhocine Ali

    2013-01-01

    Full Text Available The main purpose of this study is to analysis the thermomechanical behavior of the dry contact between the brake disc and pads during the braking phase. The simulation strategy is based on the calculation code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

  20. Modeling the elastic behavior of ductile cast iron including anisotropy in the graphite nodules

    DEFF Research Database (Denmark)

    Andriollo, Tito; Thorborg, Jesper; Hattel, Jesper Henri

    2016-01-01

    This paper presents a micro-mechanical approach to model the intrinsic elastic anisotropy of the graphite particles in ductile iron. Contrary to most of the published works in the field, the constitutive behavior is directly derived on the basis of the nodule characteristic internal structure......, composed of graphite platelets arranged into conical sectors. In this way, the large uncertainty traditionally associated with local mechanical measurements of micro-hardness is eliminated. The proposed anisotropic description is validated by simulating the macroscopic ductile iron elastic response...

  1. Differential Reinforcement of Alternative Behavior in Center-Based Classrooms: Evaluation of Pre-Teaching the Alternative Behavior

    Science.gov (United States)

    LeGray, Matthew W.; Dufrene, Brad A.; Mercer, Sterett; Olmi, D. Joe; Sterling, Heather

    2013-01-01

    This study investigated the effectiveness of a differential reinforcement of alternative behavior procedure in decreasing disruptive behavior while simultaneously increasing the appropriate behavior of four children of typical development between the ages of 4 and 6 in center-based classrooms. We began with brief functional analyses for each…

  2. Aging Behavior of Mg-Y-Zr and Mg-Nd-Zr Cast Alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aging behavior of Mg-3.6Y-0.5Zr and Mg-2.7Nd-0.5Zr alloys was investigated by microhardness measurement and transmission electron microscopy. In the case of Mg-Y-Zr alloy, the presence of β″ phase, a major strengthener, having base centered orthorhombic structure with its lattice constants of aβ″=0.64 nm, bβ″=2.22 nm,and cβ″=0.52 nm was identified. In the case of Mg-Nd-Zr alloy aged at 250℃, the presence ofβ″ and β′phases was identified. The crystal structure ofβ″ phase was found to be DO19 and its orientation relationships with Mg matrix were [0001]β″//[0001]Mg and [01-10]β″//[0110]Mg. The β′ phase had face centered cubicstructure and its orientation relationships with Mg matrix were [011]β′//[0001]Mg and [-11-1]β′//[-2110]Mg.The Mg-2.7Nd-0.5Zr alloy showed higher hardness compared with Mg-3.6Y-0.5Zr alloy.

  3. Differentiated cell behavior: a multiscale approach using measure theory.

    Science.gov (United States)

    Colombi, Annachiara; Scianna, Marco; Tosin, Andrea

    2015-11-01

    This paper deals with the derivation of a collective model of cell populations out of an individual-based description of the underlying physical particle system. By looking at the spatial distribution of cells in terms of time-evolving measures, rather than at individual cell paths, we obtain an ensemble representation stemming from the phenomenological behavior of the single component cells. In particular, as a key advantage of our approach, the scale of representation of the system, i.e., microscopic/discrete vs. macroscopic/continuous, can be chosen a posteriori according only to the spatial structure given to the aforesaid measures. The paper focuses in particular on the use of different scales based on the specific functions performed by cells. A two-population hybrid system is considered, where cells with a specialized/differentiated phenotype are treated as a discrete population of point masses while unspecialized/undifferentiated cell aggregates are represented by a continuous approximation. Numerical simulations and analytical investigations emphasize the role of some biologically relevant parameters in determining the specific evolution of such a hybrid cell system.

  4. Cast iron - a predictable material

    Directory of Open Access Journals (Sweden)

    Jorg C. Sturm

    2011-02-01

    Full Text Available High strength compacted graphite iron (CGI or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of castings. The support of the feeding related layout of the casting is still one of the most important duties for casting process simulation. Depending on the alloy poured, different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free casting. Therefore, it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature fields. To be able to quantitatively predict these defects, solidification simulation had to be combined with density and mass transport calculations, in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding ranges. For cast iron foundries, the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes, especially since the influence of alloying elements, melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast iron. This allows the prediction of local structures, phases and ultimately the local mechanical properties of cast irons, to asses casting quality in the foundry but also to make use of this quantitative information during design of the casting. Casting quality issues related to thermally driven

  5. Differential effects of dietary oils on emotional and cognitive behaviors.

    Directory of Open Access Journals (Sweden)

    Keiko Kato

    Full Text Available Several dietary oils have been used preventatively and therapeutically in the setting of neurological disease. However, the mechanisms underlying their influence on brain function and metabolism remain unknown. It was investigated whether 3 types of dietary oils affected emotional behaviors in mice. Wild-type (WT mice and sialyltransferase ST3Gal IV-knockout (KO mice, which exhibit increased emotional and cognitive behaviors, were fed diets containing 20% dietary oils from post-weaning to adulthood. Mice were fed pellets made from control feed AIN93G powder containing 18% fish oil, soybean oil, or a mixture of 1-palmitoyl-2-oleoyl-3-palmitoyl glycerol (POP and 1-stearoyl-2-oleoyl-3-stearoyl glycerol (SOS, plus 2% soybean oil. Once mice reached adulthood, they were subjected to fear conditioning test to measure cognitive anxiety and forced swim test to measure depression. WT mice fed the POP-SOS diet showed a 0.6-fold decrease in percent freezing with contextual fear compared with WT mice fed the control diet. KO mice fed the fish oil diet showed a 1.4-fold increase in percent freezing with contextual fear compared with KO mice fed the control diet. These findings indicate that response to contextual fear was improved in WT mice that consumed POP-SOS but aggravated in KO mice that consumed fish oils. Furthermore, KO mice showed a 0.4-fold decrease in percent freezing in response to tone fear when they were fed POP-SOS diet compared to a control diet. Thus, POP-SOS diet reduced tone fear level of KO mice until the same level of WT mice. Finally, KO mice fed the soybean oil diet showed a 1.7-fold increase in immobility in the forced swim test compared to KO mice fed the control diet. Taken together, oil-rich diets differentially modulate anxiety and depression in normal and anxious mice. Oils rich in saturated fatty acids may alleviate anxiety more strongly than other oils.

  6. The effects of differential negative reinforcement of other behavior and noncontingent escape on compliance.

    OpenAIRE

    Kodak, Tiffany; Miltenberger, Raymond G; Romaniuk, Cathryn

    2003-01-01

    The present study evaluated the effects of noncontingent escape and differential negative reinforcement of other behavior in reducing problem behaviors and increasing compliance in 2 children with disabilities. Results showed that both methods reduced problem behavior and increased compliance for both children.

  7. Caste System

    OpenAIRE

    Hoff, Karla

    2016-01-01

    In standard economics, individuals are rational actors and economic forces undermine institutions that impose large inefficiencies. The persistence of the caste system is evidence of the need for psychologically more realistic models of decision-making in economics. The caste system divides South Asian society into hereditary groups whose lowest ranks are represented as innately polluted. ...

  8. DNA methylation is widespread and associated with differential gene expression in castes of the honeybee, Apis mellifera.

    Science.gov (United States)

    Elango, Navin; Hunt, Brendan G; Goodisman, Michael A D; Yi, Soojin V

    2009-07-07

    The recent, unexpected discovery of a functional DNA methylation system in the genome of the social bee Apis mellifera underscores the potential importance of DNA methylation in invertebrates. The extent of genomic DNA methylation and its role in A. mellifera remain unknown, however. Here we show that genes in A. mellifera can be divided into 2 distinct classes, one with low-CpG dinucleotide content and the other with high-CpG dinucleotide content. This dichotomy is explained by the gradual depletion of CpG dinucleotides, a well-known consequence of DNA methylation. The loss of CpG dinucleotides associated with DNA methylation also may explain the unusual mutational patterns seen in A. mellifera that lead to AT-rich regions of the genome. A detailed investigation of this dichotomy implicates DNA methylation in A. mellifera development. High-CpG genes, which are predicted to be hypomethylated in germlines, are enriched with functions associated with developmental processes, whereas low-CpG genes, predicted to be hypermethylated in germlines, are enriched with functions associated with basic biological processes. Furthermore, genes more highly expressed in one caste than another are overrepresented among high-CpG genes. Our results highlight the potential significance of epigenetic modifications, such as DNA methylation, in developmental processes in social insects. In particular, the pervasiveness of DNA methylation in the genome of A. mellifera provides fertile ground for future studies of phenotypic plasticity and genomic imprinting.

  9. Corrosion behavior of as-cast Mg-8Li-3Al+ xCe alloy in 3.5wt% NaCl solution

    Science.gov (United States)

    Manivannan, S.; Dinesh, P.; Mahemaa, R.; MariyaPillai, Nandhakumaran; Kumaresh Babu, S. P.; Sundarrajan, Srinivasan

    2016-10-01

    Mg-8Li-3Al+ xCe alloys ( x = 0.5wt%, 1.0wt%, and 1.5wt%) were prepared through a casting route in an electric resistance furnace under a controlled atmosphere. The cast alloys were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The corrosion behavior of the as-cast Mg-8Li-3Al+ xCe alloys were studied under salt spray tests in 3.5wt% NaCl solution at 35°C, in accordance with standard ASTM B-117, in conjunction with potentiodynamic polarization (PDP) tests. The results show that the addition of Ce to Mg-8Li-3Al (LA83) alloy results in the formation of Al2Ce intermetallic phase, refines both the α-Mg phase and the Mg17Al12 intermetallic phase, and then increases the microhardness of the alloys. The results of PDP and salt spray tests reveal that an increase in Ce content to 1.5wt% decreases the corrosion rate. The best corrosion resistance is observed for the LA83 alloy sample with 1.0wt% Ce.

  10. Effects of the Exposure to Corrosive Salts on the Frictional Behavior of Gray Cast Iron and a Titanium-Based Metal Matrix Composite

    Energy Technology Data Exchange (ETDEWEB)

    Blau, Peter Julian [ORNL; Truhan, Jr., John J [ORNL; Kenik, Edward A [ORNL

    2007-01-01

    The introduction of increasingly aggressive road-deicing chemicals has created significant and costly corrosion problems for the trucking industry. From a tribological perspective, corrosion of the sliding surfaces of brakes after exposure to road salts can create oxide scales on the surfaces that affect friction. This paper describes experiments on the effects of exposure to sodium chloride and magnesium chloride sprays on the transient frictional behavior of cast iron and a titanium-based composite sliding against a commercial brake lining material. Corrosion scales on cast iron initially act as abrasive third-bodies, then they become crushed, spread out, and behave as a solid lubricant. The composition and subsurface microstructures of the corrosion products on the cast iron were analyzed. Owing to its greater corrosion resistance, the titanium composite remained scale-free and its frictional response was markedly different. No corrosion scales were formed on the titanium composite after aggressive exposure to salts; however, a reduction in friction was still observed. Unlike the crystalline sodium chloride deposits that tended to remain dry, hygroscopic magnesium chloride deposits absorbed ambient moisture from the air, liquefied, and retained a persistent lubricating effect on the titanium surfaces.

  11. Rotary bending fatigue behavior of A356 –T6 aluminum alloys by vacuum pressurizing casting

    Directory of Open Access Journals (Sweden)

    Yong-qin Liu

    2015-09-01

    Full Text Available Vacuum pressurizing casting technique, providing better mould filling and inter-dendritic feeding, can reduce the porosity greatly in cast aluminum alloys, and improve the fatigue properties. The rotary bending fatigue properties of A356-T6 alloys prepared by vacuum pressurizing casting were investigated. The S-N curve and limit strength 90 MPa under fatigue life of 107 cycles were obtained. The analyses on the fatigue fractography and microstructure of specimens showed that the fatigue fracture mainly occurs at the positions with casting defects in the subsurface, especially at porosities regions, which attributed to the crack propagation during the fatigue fracture process. Using the empirical crack propagation law of Pairs-Erdogon, the quantitative relationship among the initial crack size, fatigue life and applied stress was established. The fatigue life decreases with an increase in initial crack size. Two constants in the Pairs-Erdogon equation of aluminum alloy A356-T6 were calculated using the experimental data.

  12. Local behavior of autonomous neutral functional differential equations.

    Science.gov (United States)

    Hale, J. K.

    1972-01-01

    Basic problems for a special class of neutral functional differential equations (NFDE) are formulated, and some contributions to a general qualitative theory in the neighborhood of an equilibrium point are indicated. The properties of a NFDE (G,f) are examined to determine in what sense these properties are insensitive to small changes in (G,f) in the topology G x F. The special class of equations that is introduced includes retarded functional differential equations and difference equations.

  13. Development of an RNA interference tool, characterization of its target, and an ecological test of caste differentiation in the eusocial wasp polistes.

    Directory of Open Access Journals (Sweden)

    James H Hunt

    Full Text Available Recent advancements in genomics provide new tools for evolutionary ecological research. The paper wasp genus Polistes is a model for social insect evolution and behavioral ecology. We developed RNA interference (RNAi-mediated gene silencing to explore proposed connections between expression of hexameric storage proteins and worker vs. gyne (potential future foundress castes in naturally-founded colonies of P. metricus. We extended four fragments of putative hexamerin-encoding P. metricus transcripts acquired from a previous study and fully sequenced a gene that encodes Hexamerin 2, one of two proposed hexameric storage proteins of P. metricus. MALDI-TOF/TOF, LC-MSMS, deglycosylation, and detection of phosphorylation assays showed that the two putative hexamerins diverge in peptide sequence and biochemistry. We targeted the hexamerin 2 gene in 5(th (last-instar larvae by feeding RNAi-inducing double-stranded hexamerin 2 RNA directly to larvae in naturally-founded colonies in the field. Larval development and adult traits were not significantly altered in hexamerin 2 knockdowns, but there were suggestive trends toward increased developmental time and less developed ovaries, which are gyne characteristics. By demonstrating how data acquisition from 454/Roche pyrosequencing can be combined with biochemical and proteomics assays and how RNAi can be deployed successfully in field experiments on Polistes, our results pave the way for functional genomic research that can contribute significantly to learning the interactions of environment, development, and the roles they play in paper wasp evolution and behavioral ecology.

  14. Planarian Phototactic Assay Reveals Differential Behavioral Responses Based on Wavelength.

    Directory of Open Access Journals (Sweden)

    Taylor R Paskin

    Full Text Available Planarians are free-living aquatic flatworms that possess a well-documented photophobic response to light. With a true central nervous system and simple cerebral eyes (ocelli, planarians are an emerging model for regenerative eye research. However, comparatively little is known about the physiology of their photoreception or how their behavior is affected by various wavelengths. Most phototactic studies have examined planarian behavior using white light. Here, we describe a novel planarian behavioral assay to test responses to small ranges of visible wavelengths (red, blue, green, as well as ultraviolet (UV and infrared (IR which have not previously been examined. Our data show that planarians display behavioral responses across a range of wavelengths. These responses occur in a hierarchy, with the shortest wavelengths (UV causing the most intense photophobic responses while longer wavelengths produce no effect (red or an apparent attraction (IR. In addition, our data reveals that planarian photophobia is comprised of both a general photophobic response (that drives planarians to escape the light source regardless of wavelength and wavelength-specific responses that encompass specific behavioral reactions to individual wavelengths. Our results serve to improve the understanding of planarian phototaxis and suggest that behavioral studies performed with white light mask a complex behavioral interaction with the environment.

  15. Linear-quadratic control and quadratic differential forms for multidimensional behaviors

    NARCIS (Netherlands)

    Napp, D.; Trentelman, H.L.

    2011-01-01

    This paper deals with systems described by constant coefficient linear partial differential equations (nD-systems) from a behavioral point of view. In this context we treat the linear-quadratic control problem where the performance functional is the integral of a quadratic differential form. We look

  16. Asymptotic behavior and stability of second order neutral delay differential equations

    NARCIS (Netherlands)

    Chen, G.L.; van Gaans, O.W.; Verduyn Lunel, Sjoerd

    2014-01-01

    We study the asymptotic behavior of a class of second order neutral delay differential equations by both a spectral projection method and an ordinary differential equation method approach. We discuss the relation of these two methods and illustrate some features using examples. Furthermore, a fixed

  17. Planarian Phototactic Assay Reveals Differential Behavioral Responses Based on Wavelength

    OpenAIRE

    Paskin, Taylor R.; John Jellies; Jessica Bacher; Wendy S Beane

    2014-01-01

    Planarians are free-living aquatic flatworms that possess a well-documented photophobic response to light. With a true central nervous system and simple cerebral eyes (ocelli), planarians are an emerging model for regenerative eye research. However, comparatively little is known about the physiology of their photoreception or how their behavior is affected by various wavelengths. Most phototactic studies have examined planarian behavior using white light. Here, we describe a novel planarian b...

  18. Social interactions affecting caste development through physiological actions in termites.

    Science.gov (United States)

    Watanabe, Dai; Gotoh, Hiroki; Miura, Toru; Maekawa, Kiyoto

    2014-01-01

    A colony of social insects is not only an aggregation of individuals but also a functional unit. To achieve adaptive social behavior in fluctuating environmental conditions, in addition to coordination of physiological status in each individual, the whole colony is coordinated by interactions among colony members. The study on the regulation of social-insect colonies is termed "social physiology." Termites, a major group of social insects, exhibit many interesting phenomena related to social physiology, such as mechanisms of caste regulation in a colony. In their colonies, there are different types of individuals, i.e., castes, which show distinctive phenotypes specialized in specific colony tasks. Termite castes comprise reproductives, soldiers and workers, and the caste composition can be altered depending on circumstances. For the regulation of caste compositions, interactions among individuals, i.e., social interactions, are thought to be important. In this article, we review previous studies on the adaptive meanings and those on the proximate mechanisms of the caste regulation in termites, and try to understand those comprehensively in terms of social physiology. Firstly, we summarize classical studies on the social interactions. Secondly, previous studies on the pheromone substances that mediate the caste regulatory mechanisms are overviewed. Then, we discuss the roles of a physiological factor, juvenile hormone (JH) in the regulation of caste differentiation. Finally, we introduce the achievements of molecular studies on the animal sociality (i.e., sociogenomics) in terms of social physiology. By comparing the proximate mechanisms of social physiology in termites with those in hymenopterans, we try to get insights into the general principles of social physiology in social animals.

  19. Unusual Solidification Behavior of the Suction-Cast Cu-Zr-Al-Y Alloy Doped with Fe

    Science.gov (United States)

    Kozieł, Tomasz; Cios, Grzegorz; Latuch, Jerzy; Pajor, Krzysztof; Bała, Piotr

    2017-04-01

    The effect of iron addition on the microstructure of the Cu-Zr-Al-Y glass-forming alloy was studied. Despite a high superficial cooling rate, small Fe additions (1.5 and 3 pct) induced formation of crystalline CuZr and AlCu2Zr phases on the outer layers of suction-cast rods. As the melt composition near the solid/liquid interface was depleted in Fe, the remaining melt vitrified at a relatively low cooling rate.

  20. Predicting Stress vs. Strain Behaviors of Thin-Walled High Pressure Die Cast Magnesium Alloy with Actual Pore Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoo Sil; Barker, Erin; Cheng, Guang; Sun, Xin; Forsmark, Joy; Li, Mei

    2016-01-06

    In this paper, a three-dimensional (3D) microstructure-based finite element modeling method (i.e., extrinsic modeling method) is developed, which can be used in examining the effects of porosity on the ductility/fracture of Mg castings. For this purpose, AM60 Mg tensile samples were generated under high-pressure die-casting in a specially-designed mold. Before the tensile test, the samples were CT-scanned to obtain the pore distributions within the samples. 3D microstructure-based finite element models were then developed based on the obtained actual pore distributions of the gauge area. The input properties for the matrix material were determined by fitting the simulation result to the experimental result of a selected sample, and then used for all the other samples’ simulation. The results show that the ductility and fracture locations predicted from simulations agree well with the experimental results. This indicates that the developed 3D extrinsic modeling method may be used to examine the influence of various aspects of pore sizes/distributions as well as intrinsic properties (i.e., matrix properties) on the ductility/fracture of Mg castings.

  1. Solidification and casting

    CERN Document Server

    Cantor, Brian

    2002-01-01

    INDUSTRIAL PERSPECTIVEDirect chillcasting of aluminium alloysContinuous casting of aluminium alloysContinuous casting of steelsCastings in the automotive industryCast aluminium-silicon piston alloysMODELLING AND SIMULATIONModelling direct chill castingMold filling simulation of die castingThe ten casting rulesGrain selection in single crystal superalloy castingsDefects in aluminium shape castingPattern formation during solidificationPeritectic solidificationSTRUCTURE AND DEFECTSHetergeneous nucleation in aluminium alloysCo

  2. Oscillatory and Asymptotic Behavior of a Second-Order Nonlinear Functional Differential Equations

    Institute of Scientific and Technical Information of China (English)

    张全信; 高丽; 王少英

    2012-01-01

    This paper is concerned with oscillatory and asymptotic behavior of solutions of a class of second order nonlinear functional differential equations. By using the generalized Riccati transformation and the integral averaging technique, new oscillation criteria and asymptotic behavior are obtained for all solutions of the equation. Our results generalize and improve some known theorems.

  3. Comparing Main and Collateral Effects of Extinction and Differential Reinforcement of Alternative Behavior

    Science.gov (United States)

    Petscher, Erin Seligson; Bailey, Jon S.

    2008-01-01

    This study evaluated the effects and collateral effects of extinction (EXT) and differential reinforcement of alternative behavior (DRA) interventions with inappropriate vocalizations and work refusal. Both interventions have been used frequently to reduce problem behaviors. The benefits of these interventions have been established yet may be…

  4. Differential self-assembly behaviors of cyclic and linear peptides.

    Science.gov (United States)

    Choi, Sung-ju; Jeong, Woo-jin; Kang, Seong-Kyun; Lee, Myongsoo; Kim, Eunhye; Ryu, Du Yeol; Lim, Yong-beom

    2012-07-01

    Here we ask the fundamental questions about the effect of peptide topology on self-assembly. The study revealed that the self-assembling behaviors of cyclic and linear peptides are significantly different in several respects, in addition to sharing several similarities. Their clear differences included the morphological dissimilarities of the self-assembled nanostructures and their thermal stability. The similarities include their analogous critical aggregation concentration values and cytotoxicity profiles, which are in fact closely related. We believe that understanding topology-dependent self-assembly behavior of peptides is important for developing tailor-made self-assembled peptide nanostructures.

  5. A chromatin link to caste identity in the carpenter ant Camponotus floridanus.

    Science.gov (United States)

    Simola, Daniel F; Ye, Chaoyang; Mutti, Navdeep S; Dolezal, Kelly; Bonasio, Roberto; Liebig, Jürgen; Reinberg, Danny; Berger, Shelley L

    2013-03-01

    In many ant species, sibling larvae follow alternative ontogenetic trajectories that generate striking variation in morphology and behavior among adults. These organism-level outcomes are often determined by environmental rather than genetic factors. Therefore, epigenetic mechanisms may mediate the expression of adult polyphenisms. We produced the first genome-wide maps of chromatin structure in a eusocial insect and found that gene-proximal changes in histone modifications, notably H3K27 acetylation, discriminate two female worker and male castes in Camponotus floridanus ants and partially explain differential gene expression between castes. Genes showing coordinated changes in H3K27ac and RNA implicate muscle development, neuronal regulation, and sensory responses in modulating caste identity. Binding sites of the acetyltransferase CBP harbor the greatest caste variation in H3K27ac, are enriched with motifs for conserved transcription factors, and show evolutionary expansion near developmental and neuronal genes. These results suggest that environmental effects on caste identity may be mediated by differential recruitment of CBP to chromatin. We propose that epigenetic mechanisms that modify chromatin structure may help orchestrate the generation and maintenance of polyphenic caste morphology and social behavior in ants.

  6. Creating Gender Role Behavior: Demonstrating the Impact of Power Differentials.

    Science.gov (United States)

    Collins, Lynn H.

    2000-01-01

    Describes a demonstration that draws parallels between the Zimbardo prison experiment and the impact that assignment to low and high power roles can have on the behavior of men and women. Finds that students rated women as more similar to prisoners (subordinate role) and men as more similar to guards (dominant role). (CMK)

  7. Creep-rupture behavior of a developmental cast-iron-base alloy for use up to 800 deg C

    Science.gov (United States)

    Titran, Robert H.; Scheuermann, Coulson M.

    1987-01-01

    A promising iron-base cast alloy is being developed as part of the DOE/NASA Stirling Engine Systems Project under contract DEN 3-282 with the United Technologies Research Center. This report presents the results of a study at the Lewis Research Center of the alloy's creep-rupture properties. The alloy was tested under a variety of conditions and was found to exhibit the normal 3-stage creep response. The alloy compared favorably with others being used or under consideration for the automotive Stirling engine cylinder/regenerator housing.

  8. Microstructural effects on the wear behavior of a biomedical as-cast Co-27Cr-5Mo-0.25C alloy exposed to pulsed laser melting.

    Science.gov (United States)

    Acevedo-Dávila, J L; López, H F; Cepeda-Rodríguez, F; Rodriguez-Reyes, M; García-Vazquez, F; Hernández-Garcia, H M

    2014-06-01

    In this work, the effect of pulsed laser melting on the exhibited microstructure and properties of a cast Co-27Cr-5Mo-0.25C alloy was investigated. In particular, properties such as surface hardness and wear behavior of the laser modified microstructure were determined as a function of the implemented laser melting parameters. It was found that laser melting promotes significant grain refinement while preventing the precipitation of coarse carbide phases. Apparently, a refined dendritic grain structure develops which is surrounded by a fine carbide distribution in the interdendritic regions. Moreover, the high-temperature face centered cubic (FCC) phase remains untransformed at room temperature. Hardness measurements and wear testing using a Pin-On-Disk tribological machine indicate that the modified laser surfaces exhibit both, high wear resistance and high microhardness when compared with the untreated as-cast Co-27Cr-5Mo-0.25C alloy. In particular, it was found that the laser modified surfaces exhibit improved wear and friction properties comparable to the ones found in Co-Cr-Mo alloys with a predominantly hexagonal closest packed (HCP) matrix. However, surface defects associated with the laser process can be detrimental for the improved wear performance and they should be considered in identifying the proper laser parameters in alloy melting.

  9. Effects of N/C Ratio on Solidification Behaviors of Novel Nb-Bearing Austenitic Heat-Resistant Cast Steels for Exhaust Components of Gasoline Engines

    Science.gov (United States)

    Zhang, Yinhui; Li, Mei; Godlewski, Larry A.; Zindel, Jacob W.; Feng, Qiang

    2017-03-01

    In order to comply with more stringent environmental and fuel consumption regulations, novel Nb-bearing austenitic heat-resistant cast steels that withstand exhaust temperatures as high as 1,323 K (1,050 °C) is urgently demanded from automotive industries. In the current research, the solidification behavior of these alloys with variations of N/C ratio is investigated. Directional solidification methods were carried out to examine the microstructural development in mushy zones. Computational thermodynamic calculations under partial equilibrium conditions were performed to predict the solidification sequence of different phases. Microstructural characterization of the mushy zones indicates that N/C ratio significantly influenced the stability of γ-austenite and the precipitation temperature of NbC/Nb(C,N), thereby altering the solidification path, as well as the morphology and distribution of NbC/Nb(C,N) and γ-ferrite. The solidification sequence of different phases predicted by thermodynamic software agreed well with the experimental results, except the specific precipitation temperatures. The generated data and fundamental understanding will be helpful for the application of computational thermodynamic methods to predict the as-cast microstructure of Nb-bearing austenitic heat-resistant steels.

  10. Deformation Behavior and Microstructure Evolution of As-Cast 42CrMo Alloy in Isothermal and Non-isothermal Compression

    Science.gov (United States)

    Qin, Fangcheng; Li, Yongtang; Qi, Huiping; Lv, Zhenhua

    2016-11-01

    The isothermal and non-isothermal multi-pass compression tests of centrifugal casting 42CrMo steel were conducted on a Gleeble-3500 thermal simulation machine. The effects of compression passes and finishing temperatures on deformation behavior and microstructure evolution were investigated. It is found that the microstructure is homogeneous with equiaxed grains, and the flow stress does not show significant change with the increase in passes, while the peak softening coefficient increases first and then decreases during inter-pass. Moreover, the dominant mechanisms of controlled temperature and accumulated static recrystallization for grain refinement and its homogeneous distribution are found after 5 passes deformation. As the finishing temperature increases, the flow stress decreases gradually, but the dynamic recrystallization accelerates and softening effect increases, resulting in the larger grain size and homogeneous microstructure. The microhardness decreases sharply because the sufficient softening occurs in microstructure. When the finishing temperature is 890 °C, the carbide particles are precipitated in the vicinity of the grain boundaries, thus inhibiting the dislocation motion. Thus, the higher finishing temperature (≥970 °C) for centrifugal casting 42CrMo alloy should be avoided in non-isothermal multi-pass deformation, which is beneficial to grain refinement and properties improvement.

  11. Effects of N/C Ratio on Solidification Behaviors of Novel Nb-Bearing Austenitic Heat-Resistant Cast Steels for Exhaust Components of Gasoline Engines

    Science.gov (United States)

    Zhang, Yinhui; Li, Mei; Godlewski, Larry A.; Zindel, Jacob W.; Feng, Qiang

    2017-01-01

    In order to comply with more stringent environmental and fuel consumption regulations, novel Nb-bearing austenitic heat-resistant cast steels that withstand exhaust temperatures as high as 1,323 K (1,050 °C) is urgently demanded from automotive industries. In the current research, the solidification behavior of these alloys with variations of N/C ratio is investigated. Directional solidification methods were carried out to examine the microstructural development in mushy zones. Computational thermodynamic calculations under partial equilibrium conditions were performed to predict the solidification sequence of different phases. Microstructural characterization of the mushy zones indicates that N/C ratio significantly influenced the stability of γ-austenite and the precipitation temperature of NbC/Nb(C,N), thereby altering the solidification path, as well as the morphology and distribution of NbC/Nb(C,N) and γ-ferrite. The solidification sequence of different phases predicted by thermodynamic software agreed well with the experimental results, except the specific precipitation temperatures. The generated data and fundamental understanding will be helpful for the application of computational thermodynamic methods to predict the as-cast microstructure of Nb-bearing austenitic heat-resistant steels.

  12. Part I: In-situ fluorometric quantification of microalgal neutral lipids. Part II: Thermal degradation behavior of investment casting polymer patterns

    Science.gov (United States)

    Zhao, Hongfang

    Research described in this dissertation covers two topics. Part-I is focused on in-situ determination of neutral lipid content of microalgae using a lipophilic fluorescent dye. The traditional Nile red stain-based method for detecting microalgal intracellular lipids is limited due to varying composition and thickness of rigid cell walls. In this study, the addition of dilute acid and heating of solution, were found to greatly enhance staining efficiency of Nile red for microalgal species evaluated. Oil-in-water (O/W) microemulsion stabilized by a non-ionic surfactant was employed as a pseudo-standard that mimics lipid-bearing microalgal cells suspended in water. The average neutral lipid contents determined were very close to the results obtained by traditional gravimetric method and solid phase extraction. Part II of the dissertation explores thermo-physico-chemical properties of polymeric pattern materials, including expanded polystyrene (EPS) foam, polyurethane foam, and epoxy stereolithography (SLA) patterns, that are used in investment casting. Density, elastic modulus, expansion coefficient, thermal degradation behavior, etc. were experimentally investigated for their effects on metal casting quality. The reduction in toxic hydrogen cyanide (HCN) generated during thermal decomposition of polyurethane pattern was achieved by increasing either oxidant level or residence time in heated zone. Thermal degradation kinetics of the pattern materials were examined with a thermogravimetric analysis and activation energies were determined by Kissinger and Flynn-Wall-Ozawa methods.

  13. Shadows cast on the transition disk of HD 135344B. Multiwavelength VLT/SPHERE polarimetric differential imaging

    Science.gov (United States)

    Stolker, T.; Dominik, C.; Avenhaus, H.; Min, M.; de Boer, J.; Ginski, C.; Schmid, H. M.; Juhasz, A.; Bazzon, A.; Waters, L. B. F. M.; Garufi, A.; Augereau, J.-C.; Benisty, M.; Boccaletti, A.; Henning, Th.; Langlois, M.; Maire, A.-L.; Ménard, F.; Meyer, M. R.; Pinte, C.; Quanz, S. P.; Thalmann, C.; Beuzit, J.-L.; Carbillet, M.; Costille, A.; Dohlen, K.; Feldt, M.; Gisler, D.; Mouillet, D.; Pavlov, A.; Perret, D.; Petit, C.; Pragt, J.; Rochat, S.; Roelfsema, R.; Salasnich, B.; Soenke, C.; Wildi, F.

    2016-11-01

    Context. The protoplanetary disk around the F-type star HD 135344B (SAO 206462) is in a transition stage and shows many intriguing structures both in scattered light and thermal (sub-)millimeter emission which are possibly related to planet formation processes. Aims: We aim to study the morphology and surface brightness of the disk in scattered light to gain insight into the innermost disk regions, the formation of protoplanets, planet-disk interactions traced in the surface and midplane layers, and the dust grain properties of the disk surface. Methods: We have carried out high-contrast polarimetric differential imaging (PDI) observations with VLT/SPHERE and obtained polarized scattered light images with ZIMPOL in the R and I-bands and with IRDIS in the Y and J-bands. The scattered light images and surface brightness profiles are used to study in detail structures in the disk surface and brightness variations. We have constructed a 3D radiative transfer model to support the interpretation of several detected shadow features. Results: The scattered light images reveal with unprecedented angular resolution and sensitivity the spiral arms as well as the 25 au cavity of the disk. Multiple shadow features are discovered on the outer disk with one shadow only being present during the second observation epoch. A positive surface brightness gradient is observed in the stellar irradiation corrected (r2-scaled) images in southwest direction possibly due to an azimuthally asymmetric perturbation of the temperature and/or surface density by the passing spiral arms. The disk integrated polarized flux, normalized to the stellar flux, shows a positive trend towards longer wavelengths which we attribute to large (2πa ≳ λ) aggregate dust grains in the disk surface. Part of the non-azimuthal polarization signal in the Uφ image of the J-band observation can be attributed to multiple scattering in the disk. Conclusions: The detected shadow features and their possible variability

  14. Leaching Behavior and Potential Environmental Effects of Trace Elements in Coal Gangue of an Open-Cast Coal Mine Area, Inner Mongolia, China

    Directory of Open Access Journals (Sweden)

    Liu Yang

    2016-05-01

    Full Text Available In order to better understand the role of coal gangue in potential environmental and ecological risks, the leaching behavior of trace elements from coal gangue has been investigated in an open-cast coal mine, Inner Mongolia, China. Four comparative column leaching experiments were conducted to investigate the impacts of leaching time, pH values and sample amount on the leaching behavior of trace elements. Enrichment factors (EF, maximum leached amount (Lam, maximum leachability (Lrm, effects range low (ERL and effects range median (ERM were employed to evaluate potential environmental and ecological hazards resulting from the leaching behavior of environment-sensitive trace elements from coal gangue. Leaching time and sample amount display important effects on trace element concentrations, leached amounts and leachability. The pH values exhibit a weak influence on the leaching behavior of the selected trace elements (e.g., As, V, Cr, Co, Ni, Cu, Zn, Se, Cd, Sn, Pb and Hg. The coal gangue are enriched in As, Co, Se and Pb and, in particular, show higher environmental pollution levels of As and Se (EF > 2. Lam values suggest that all of the elements investigated do not show potential risk to soils and vegetation, but have a high hazard risk for ground water. Elements including Ni, As, Cr and Zn are inclined to show high or moderate biological toxicity.

  15. Wear Behavior of Al-Mg2Si Cast In-situ Composite: Effect of Mg2Si Different Volume Fractions

    Science.gov (United States)

    Ghiasinejad, J.; Emamy, M.; Ghorbani, M. R.; Malekan, A.

    2010-06-01

    Al-Mg2Si in situ composites are great candidates for automobile brake discs due to their low density, reasonably high young's modulus and low thermal expansion coefficient. Thus, understanding wear properties of this composite is of a great importance. In this study wear behavior of an in-situ Al-Mg2Si composite, prepared from a simple casting route, has been investigated using a pin-on-disc configuration concerning the effect of Mg2Si volume fractions, 15, 20 and 25% respectively. It was found that the weight loss increases with increase in reinforce volume fraction which can be due to a coarse morphology of primary Mg2Si particles. It was found that the variations of weight loss with sliding distance comprise different regimes of which the mechanisms are discussed.

  16. Microstructure and Wear Behavior Of as Cast Al-25mg2si-2cu-2ni Alloy

    Directory of Open Access Journals (Sweden)

    1Geetanjali.S.Guggari ,

    2015-09-01

    Full Text Available The remarkable feature of the Aluminium is its low density and ability to withstand corrosion effect due to phenomenon of passivation. Structural components made from Aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The oxides and sulphate are useful compounds of Aluminium based on its weight. In this work, an attempt has been made to utilize the combined effect of high cooling rate solidification, unique micro structural evolution mechanism of T6 heat treatment the advantages of hypereutectic Al-Si system alloyed with other elements such as Cu, Fe and Mg. In the present investigation, the binary alloys in the hypereutectic range viz. Al25Mg2Si has been selected as heat resistant Al-Si alloys. A systematic approach has been carried out to explore the micro structural features, mechanical and wear properties of as cast alloys.

  17. Nodular cast iron and casting monitoring

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-10-01

    Full Text Available In this paper quality monitoring of nodular cast iron and casting made of it is presented. A control system of initial liquid cast iron to spheroidization, after spheroidization and inoculation with using of TDA method was shown. An application of an ultrasonic method to assessment of the graphite form and the metal matrix microstructure of castings was investigated.

  18. Nodular cast iron and casting monitoring

    OpenAIRE

    2008-01-01

    In this paper quality monitoring of nodular cast iron and casting made of it is presented. A control system of initial liquid cast iron to spheroidization, after spheroidization and inoculation with using of TDA method was shown. An application of an ultrasonic method to assessment of the graphite form and the metal matrix microstructure of castings was investigated.

  19. Differential Reinforcement of Communicative Behaviors (DRC): An Intervention for the Disruptive Behaviors of Developmentally Disabled Children.

    Science.gov (United States)

    Durand, V. Mark; Carr, Edward G.

    A study, involving four developmentally disabled children who exhibited a variety of disruptive behaviors such as self-injury and tantrums, was conducted to assess the influence of task demands and adult attention on children's behaviors. The three experimental conditions were the "EASY 100" which consisted of an easy task on which children could…

  20. Influence of titanium diboride reinforcements on the microstructure, mechanical properties and fracture behavior of cast zinc-aluminum composites

    Science.gov (United States)

    Dionne, Sylvie

    The objective of the present study was to examine the relationships between the microstructure, mechanical properties and failure mechanisms which control the performance of TiB2 particle reinforced Zn-8 wt.% Al (ZA-8) composites. Unreinforced ZA-8 and four composite heats with nominal particle contents of 5, 10, 20 and 30 vol.% were prepared using stir casting and permanent mold casting techniques. Tensile, compression, Charpy impact and short bar chevron-notch fracture toughness tests were conducted at room temperature. The microstructure and fracture surfaces of the specimens were characterized using optical, scanning electron, transmission electron and focused ion beam microscopy. These experimental results were compared with relevant MMC models and with published data on Zn-based composites. The TiB2/ZA-8 composites had a homogeneous distribution of particles in a matrix similar to unreinforced ZA-8. The matrix grain size decreased as the TiB2 content increased. No interfacial reaction products were detected. A good correlation was obtained between the measured composite stiffness and the values predicted using an Eshelby model. The yield strength and work hardening rate of TiB2/ZA-8 were only marginally higher than those of unreinforced ZA-8. The strength properties did not increase with the particle content as predicted by the Eshelby model. The premature activation of relaxation processes limited the extent to which particle reinforcement improved the strength of the ZA-8 matrix. Temperature-activated relaxation processes such as diffusion and dislocation motion can occur readily in ZA-8 at room temperature, which corresponds to 0.44 TM. Particle reinforcement of the ZA-8 alloy produced a degradation of the toughness which was sensitive to the loading rate. The Charpy energy of TiB 2/ZA-8 was up to 85% smaller than that of ZA-8, while the corresponding loss in fracture toughness was only 15%. The moderate fracture toughness decrease was explained by the

  1. Do Guilt- and Shame-Proneness Differentially Predict Prosocial, Aggressive, and Withdrawn Behaviors during Early Adolescence?

    Science.gov (United States)

    Roos, Sanna; Hodges, Ernest V. E.; Salmivalli, Christina

    2014-01-01

    In this short-term longitudinal study, we systematically examined the distinctiveness of guilt- and shame-proneness in early adolescents (N = 395, mean age = 11.8 years) in terms of differential relations with peer reported prosocial behavior, withdrawal, and aggression. Results from structural equation modeling indicated that guilt-proneness…

  2. Adolescent behavioral and neural reward sensitivity : a test of the differential susceptibility theory

    NARCIS (Netherlands)

    Richards, J. S.; Vasquez, A. Arias; von Rhein, D.; van der Meer, D.; Franke, B.; Hoekstra, P. J.; Heslenfeld, D. J.; Oosterlaan, J.; Faraone, S. V.; Buitelaar, J. K.; Hartman, C. A.

    2016-01-01

    Little is known about the causes of individual differences in reward sensitivity. We investigated gene-environment interactions (GxE) on behavioral and neural measures of reward sensitivity, in light of the differential susceptibility theory. This theory states that individuals carrying plasticity g

  3. Asymptotic and Oscillatory Behavior of Solutions of First Order Neutral Differential Equations

    Institute of Scientific and Technical Information of China (English)

    王其如; 李黎

    1993-01-01

    This paper has made researches on first order neutral differential equations with varia-ble coefficients and several deviations.The asymptotic behavior of nonoscillatory solutions of the equations are discussed.Necessary and sufficient conditions and several sufficient conditions for the oscillations of the equations are obtained.The relevent results in [1-3] are improved and genera-lized.

  4. Weighted asymptotic behavior of solutions to semilinear integro-differential equations in Banach spaces

    Directory of Open Access Journals (Sweden)

    Yan-Tao Bian

    2014-04-01

    Full Text Available In this article, we study weighted asymptotic behavior of solutions to the semilinear integro-differential equation $$ u'(t=Au(t+\\alpha\\int_{-\\infty}^{t}e^{-\\beta(t-s}Au(sds+f(t,u(t, \\quad t\\in \\mathbb{R}, $$ where $\\alpha, \\beta \\in \\mathbb{R}$, with $\\beta > 0, \\alpha \

  5. Parental anxiety, parenting behavior, and infant anxiety: differential associations for fathers and mothers

    NARCIS (Netherlands)

    E.L. Möller; M. Majdandžić; S.M. Bögels

    2014-01-01

    Most studies investigating the role of parenting behavior in the intergenerational transmission of anxiety from parents to children have focused on mothers. However, recent research suggests that mothers and fathers may parent differently and may differentially affect the development of child anxiet

  6. Parental anxiety, parenting behavior, and infant anxiety: differential associations for fathers and mothers

    NARCIS (Netherlands)

    Möller, E.L.; Majdandžić, M.; Bögels, S.M.

    2015-01-01

    Most studies investigating the role of parenting behavior in the intergenerational transmission of anxiety from parents to children have focused on mothers. However, recent research suggests that mothers and fathers may parent differently and may differentially affect the development of child anxiet

  7. Differential Effects of Reinforcement on the Self-Monitoring of On-Task Behavior

    Science.gov (United States)

    Otero, Tiffany L.; Haut, Jillian M.

    2016-01-01

    In the current study, the differential effects of reinforcement on a self-monitoring intervention were evaluated. Three students nominated by their teachers for having a marked difficultly maintaining on-task behaviors participated in the study. Using an alternating treatments single-case design to assess self-monitoring with and without…

  8. Differential negative reinforcement of other behavior to increase wearing of a medical bracelet.

    Science.gov (United States)

    Cook, Jennifer L; Rapp, John T; Schulze, Kimberley A

    2015-12-01

    We used a changing criterion design to evaluate the extent to which differential negative reinforcement of other behavior increased compliance with wearing a medical alert bracelet for a young boy with autism. Results showed the duration for which the participant wore the bracelet systematically increased across trials from 5 s to 7 hr over several weeks.

  9. ASYMPTOTIC BEHAVIOR OF SOLUTIONS TO SECOND ORDER IMPULSIVE DIFFERENTIAL EQUATION ON TIME SCALES

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In this paper,we investigate a second order impulsive differential equation on time scales.Sufficient conditions are given to guarantee that the solutions tend to zero.The notable effect of impulse upon the asymptotic behavior of solutions is stressed in this paper.At last,we illustrate our results with two examples.

  10. Oscillatory and Asymptotic Behavior of Solutions for Nonlinear Impulsive Delay Differential Equations

    Institute of Scientific and Technical Information of China (English)

    Wei-hua Mao; An-hua Wan

    2006-01-01

    The oscillatory and asymptotic behavior of the solutions for third order nonlinear impulsive delay differential equations are investigated. Some novel criteria for all solutions to be oscillatory or be asymptotic are established. Three illustrative examples are proposed to demonstrate the effectiveness of the conditions.

  11. Microstructure and Wear Behavior of TiC Coating Deposited on Spheroidized Graphite Cast Iron Using Laser Surfacing

    Directory of Open Access Journals (Sweden)

    E. R. I. Mahmoud

    2014-10-01

    Full Text Available Spheroidal graphite cast iron was laser cladded with TiC powder using a YAG fiber laser at powers of 700, 1000, 1500 and 2000 W. The powder was preplaced on the surface of the specimens with 0.5 mm thickness. Sound cladding and fusion zones were observed at 700, 1000 and 1500 W powers. However, at 2000 W, cracking was observed in the fusion zone. At 700 W, a build-up zone consisted of fine TiC dendrites inside a matrix composed of martensite, cementite (Fe3C, and some blocks of retained austenite was observed. In this zone, all graphite nodules were totally melted. In the fusion zone, some undissolved and partially dissolved graphite nodules appeared in a matrix containing bainite, ferrite, martensite and retained austenite. At 1500 W, the fusion zone had more iron carbides and ferrite, and the HAZ consisted of martensitic structure. At 2000 W, the build-up zone was consisted of TiC particles precipitated in a matrix of eutectic carbides, martensite plus an inter-lamellar retained austenite. The hardness of the cladded area was remarkably improved (1330 HV in case of 700 W: 5.5 times of the hardness of substrate

  12. Effect of nodule count and austempering heat treatment on segregation behavior of alloying elements in ductile cast iron

    Directory of Open Access Journals (Sweden)

    E. Akbarzadeh Chiniforush

    2016-05-01

    Full Text Available The equilibrium partition ratio, k, has been measured for Mn, Mo, Si, Ni and Cu in a ductile iron with composition (wt.%: 3.45C, 0.25Mn, 0.25Mo, 2.45Si, 0.5Ni and 0.5Cu with different nodule counts obtained from different section sizes of 13, 25, 75 mm in the as cast, austenitized (at 870 °C for times 1, 4 and 6 hours and austempered (at 375 °C for times 1 to 1,440 min samples. Results show that Mn and Mo segregate positively at cell boundaries, but Si, Ni and Cu concentrate in an inverse manner in the vicinity of graphite nodules and there is a depletion of these elements at cell boundaries. Segregation curves for Ni and Cu are more smooth than for Si. Carbide formation has been observed at cell boundaries. Based on the results, the partition ratios for all elements decrease with increasing the nodule count. More carbide with coarser morphology has been observed in the microstructure with a lower nodule count. Austenitization for a longer time can decrease partition ratio, but cannot eliminate it entirely. Increasing the austenitization temperature has the same effect. Austenitizing parameters have no significant effect on carbides volume fraction. The kinetics of austempering is faster in higher nodule counts and subsequently better mechanical properties including higher ductility, strength and toughness have been observed for all austempering conditions studied.

  13. Erosive Wear Behavior of Nickel-Based High Alloy White Cast Iron Under Mining Conditions Using Orthogonal Array

    Science.gov (United States)

    Yoganandh, J.; Natarajan, S.; Babu, S. P. Kumaresh

    2013-09-01

    Nihard Grade-4, a nickel-bearing cast iron widely used in slurry pumps and hydrodynamic components, is evaluated for its erosive wear response under mining conditions using a statistical approach. Experiments were conducted by varying the factors namely velocity, slurry concentration, angle of impingement, and pH in three levels, using L9 orthogonal array. Analysis of variance was used to rank the factors influencing erosive wear. The results indicate that velocity is the most influencing factor followed by the angle of impingement, slurry concentration, and pH. Interaction effects of velocity, slurry concentration, angle of impingement, and pH on erosion rate have been discussed. Wear morphology was also studied using SEM characterization technique. At lower angle (30°) of impingement, the erosion of material is by micro fracture and shallow ploughing with the plastic deformation of the ductile austenitic matrix. At the normal angle (90°) of impingement, the material loss from the surface is found because of deep indentation, forming protruded lips which are removed by means of repeated impact of the erodent.

  14. Tachykinin expression levels correlate with caste-specific aggression in workers of the leaf-cutting ant Acromyrmex echinatior

    Directory of Open Access Journals (Sweden)

    Jack eHowe

    2016-05-01

    Full Text Available The tachykinins are a family of neuropeptides that influence a range of behavioral phenotypes in both vertebrates and invertebrates; they appear to have a conserved role in the processing of stimuli, and in the control of aggression in a wide range of animals. Expression of tachykinin in a cluster of neurons was recently shown to determine the stimulus response threshold for aggressive behavior in Drosophila (1. Varying response thresholds are often implicated in division of labor within social insect colonies, so we hypothesized that Tachykinin could play a role in the organization of colony defense by affecting individual response thresholds to non-nestmate stimuli. We used quantitative-PCR in combination with behavioral assays to test for associations between the expression of Tachykinin and its receptor, and the aggressive division of labor among the castes of the leaf-cutting ant Acromyrmex echinatior, a species with multiple worker castes. After correction for differences in brain size among castes, we found that the most aggressive large worker caste had the highest Tachykinin expression levels, but that no such effect was apparent for breeding and virgin queens. To further evaluate these deviating results for the reproductive caste, we manipulated the aggression threshold of virgin-queens by removing their wings, which is known to make them express a soldier-like behavioral phenotype. Despite heightened aggression, expression levels of Tachykinin remained unaffected, suggesting that aggression levels in reproductive caste phenotypes are controlled by differential expression of other genes.

  15. Screening and analysis of differentially expressed genes of dermal papillae cells with aggregative behavior

    Institute of Scientific and Technical Information of China (English)

    宋志强; 郝飞; 杨卫兵; 王继文; 邹锋

    2004-01-01

    Objective: To screen and clone differentially expressed genes of dermal papillae cells (DPC) with aggregative behavior, and to explore the molecular mechanism of their aggregation. Methods: Total RNAs were extracted from DPC with and without aggregative behavior and double strand cDNAs were synthesized by using SMART cDNA synthesis, respectively. The cDNA fragments of differentially expressed genes in DPCs with aggregative behavior were isolated by suppression subtractive hybridization. Positive clones were screened by PCR method and verified by cDNA dot blot, Northern blot and then analyzed through homologous retrieving. Results: A subtractive cDNA library of DPC with aggregative behavior has been successfully constructed. The result of screening and cloning of the library showed that, DPC with aggregative behavior could expresse genes related to homologous aggregation, proliferation and cycle control, including known genes (capping protein, paladin, vascular endothelial growth factor), hematopoietic stem/progenitor cells (HSPC) related clone (HSPC011 and HSPC016) and a new gene. Conclusion: The construction of subtracted library of DPC lays solid foundation for screening and cloning new and specific genes related to aggregative behavior of DPC. Several genes might be cooperatively involved in the homologous aggregation, proliferation and cycle control of DPC. Among these genes, capping protein and palladin might be closely related to the aggregative behavior of dermal papilla cells, and VEGF and HSPC related clone would be responsible for the status of higher proliferation of dermal papilla cells.

  16. Differential Reinforcement of Alternative Behavior Increases Resistance to Extinction: Clinical Demonstration, Animal Modeling, and Clinical Test of One Solution

    Science.gov (United States)

    Mace, F. Charles; McComas, Jennifer J.; Mauro, Benjamin C.; Progar, Patrick R.; Taylor, Bridget; Ervin, Ruth; Zangrillo, Amanda N.

    2010-01-01

    Basic research with pigeons on behavioral momentum suggests that differential reinforcement of alternative behavior (DRA) can increase the resistance of target behavior to change. This finding suggests that clinical applications of DRA may inadvertently increase the persistence of target behavior even as it decreases its frequency. We conducted…

  17. Improved Foundry Castings Utilizing CAD/CAM

    Science.gov (United States)

    1981-10-01

    designed to simulate the heat transfer behavior during freezing and the subsequent cooling of an arbitrarily shaped 3D casting solidify- ing in a sand...variety of complex 2D and 3D geometries may be simulated by these routines. It is important, however, to be aware of the assumptions made in the design...three-dimensional with a sand mold surrounding a steel casting. The simulation program is desing - ed to simulate any shape. The shape of test casting

  18. Differential pathways of positive and negative health behavior change in congestive heart failure patients.

    Science.gov (United States)

    Chaves, Covadonga; Park, Crystal L

    2016-08-01

    This longitudinal study applied a stress and coping model to examine the differential pathways of perceived positive and negative health behavior changes. Participants with congestive heart failure completed self-report measures of psychological resources, coping strategies, and perceived behavior changes and were assessed again 6 months later. Patients with higher positive affect and spiritual well-being reported more positive health behavior changes over time, effects mediated by approach coping. Alternatively, patients with lower psychological resources reported more negative behavior changes over time, effects mediated by avoidance coping. The results suggest that different psychological resources are related to different types of coping which, in turn, are associated with perceived positive or negative changes in health behavior over time.

  19. Eutectic modification in a low-chromium white cast iron by a mixture of titanium, rare earths, and bismuth: Part II. effect on the wear behavior

    Science.gov (United States)

    Bedolla-Jacuinde, A.; Aguilar, S. L.; Maldonado, C.

    2005-06-01

    In this work, we studied the wear behavior of a low-Cr white cast iron (WCI) modified with ferrotitanium-rare earths-bismuth (Fe-Ti-RE-Bi) up to 2%. These additions modified the eutectic carbide structure of the alloy from continuous ledeburite into a blocky, less interconnected carbide network. The modified structure was wear tested under pure sliding conditions against a hardened M2 steel counter-face using a load of 250 N. It was observed that wear resistance increased as the modifier admixture increased. The modified structure had smaller more isolated carbides than the WCI with no Fe-Ti-RE-Bi additions. It was observed that large carbides fracture during sliding, which destabilizes the structure and causes degradation in the wear behavior. A transition from abrasive to oxidative wear after 20 km sliding occurred for all alloys. In addition, the modified alloys exhibited higher values of hardness and fracture toughness. These results are discussed in terms of the modified eutectic carbide microstructure.

  20. Influence of a novel two-step austempering process on the strain-hardening behavior of austempered ductile cast iron (ADI)

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jianghuai; Putatunda, Susil K

    2004-09-25

    An investigation was carried out to examine the influence of a novel two-step austempering process on the strain-hardening behavior of austempered ductile cast iron (ADI). Strain-hardening exponent (n value) of specimens austempered by conventional single-step austempering process as well as the novel two-step process were determined over the entire plastic deformation regions of the stress-strain curves. Optical microscopy and X-ray diffraction analysis were performed to examine mechanisms of strain-hardening behavior in ADI under monotonic (tensile) loading. Test results show that this novel two-step process has resulted in improved microstructural variables in the ADI matrix, and higher hardness, yield strength and tensile strengths, but lower ductility and strain-hardening exponent values compared to the conventional single-step austempering process. Test results also indicate that strain-hardening exponent of ADI is a function of amount and morphology of microstructural constituents and interaction intensities between carbon atoms and dislocations in the matrix.

  1. Casting materials

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhry, Anil R. (Xenia, OH); Dzugan, Robert (Cincinnati, OH); Harrington, Richard M. (Cincinnati, OH); Neece, Faurice D. (Lyndurst, OH); Singh, Nipendra P. (Pepper Pike, OH)

    2011-06-14

    A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

  2. The UK Casting Industry

    Institute of Scientific and Technical Information of China (English)

    Jincheng Liu

    2006-01-01

    The casting production in the UK in 2004 is presented and analysed. The UK casting industry has played an important role in world casting and manufacturing production. However recent years the rapid development of some developing countries has been shifting the casting production from the western industrialized countries including the UK. The UK casting industry and associated research and technology organizations, universities have been working together very hard to face the serious competition to make the UK casting industry have a sustainable future. The UK casting industry remains strong and plays an important role in world casting and manufacturing production.

  3. Insomnia Phenotypes Based on Objective Sleep Duration in Adolescents: Depression Risk and Differential Behavioral Profiles

    Directory of Open Access Journals (Sweden)

    Julio Fernandez-Mendoza

    2016-12-01

    Full Text Available Based on previous studies on the role of objective sleep duration in predicting morbidity in individuals with insomnia, we examined the role of objective sleep duration in differentiating behavioral profiles in adolescents with insomnia symptoms. Adolescents from the Penn State Child Cohort (n = 397, ages 12–23, 54.7% male underwent a nine-hour polysomnography (PSG, clinical history, physical examination and psychometric testing, including the Child or Adult Behavior Checklist and Pediatric Behavior Scale. Insomnia symptoms were defined as a self-report of difficulty falling and/or staying asleep and objective “short” sleep duration as a PSG total sleep time ≤7 h. A significant interaction showed that objective short sleep duration modified the association of insomnia symptoms with internalizing problems. Consistently, adolescents with insomnia symptoms and short sleep duration were characterized by depression, rumination, mood dysregulation and social isolation, while adolescents with insomnia symptoms and normal sleep duration were characterized by rule-breaking and aggressive behaviors and, to a lesser extent, rumination. These findings indicate that objective sleep duration is useful in differentiating behavioral profiles among adolescents with insomnia symptoms. The insomnia with objective short sleep duration phenotype is associated with an increased risk of depression earlier in the lifespan than previously believed.

  4. Gating of Permanent Molds for ALuminum Casting

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang

    2004-03-30

    This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

  5. CA Investment Casting Process of Complex Castings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    CA (Computer aided) investment casting technique used in superalloy castings of aerospace engine parts was presented. CA investment casting integrated computer application, RP (Rapid Prototyping) process, solidification simulation and investment casting process. It broke the bottle neck of making metal die. Solid model of complex parts were produced by UGII or other software, then translated into STL(Stereolithography) file, after RP process of SLS(Selective Laser Sintering), wax pattern used in investment ...

  6. Effects of alloying elements on nitrogen diffusion behavior around TiN/Ti interface α region in as-cast titanium alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To characterize the effects of alloying elements on inclusion dissolution of titanium nitride, the content profiles of elements around TiN/Ti boundary α phase regions in liquid titanium alloys have been experimentally carried out. Four kinds of commercial alloys of CpTi, Ti64, Ti17 and Ti6242 containing different α-stabilizing or β-stabilizing elements are examined through artificially embedding the TiN sponge particle into liquid alloys in VAR conditions. The content profiles of nitrogen and alloying elements around TiN/Ti boundary were measured by WDX and microprobe for as-cast samples. The content profiles of nitrogen and alloying elements around N-containing solid in αTi region of these alloys show a common features of a steep change. In particular, the content profiles of elements for Ti6242 demonstrate unique change of a more gentle change tendency and further deeper into the alloy matrix. The experiment results show that, the differences among composite effects of alloying elements in different alloys within nitrogen-induced diffusion α region result in different dissolution and diffusion behaviors to overcome the α phase region barriers.

  7. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17%Cr and Cu-17%Cr-5%Al. Part 1; Oxidation Kinetics

    Science.gov (United States)

    Raj. Sai V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu- 17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9 9.5 kJ mol-1. In contrast, the oxidation kinetics for the Cu-17%Cr- 5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR- 5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.

  8. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17 Percent Cr and Cu-17 Percent Cr-5 Percent Al. Part 1; Oxidation Kinetics

    Science.gov (United States)

    Raj, S. V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. These observations reveal that Cu-17%Cr-5%Al oxidizes at significantly slower rates than Cu-17%Cr. The rate constants for the alloys were determined from generalized analyses of the data without an a priori assumption of the nature of the oxidation kinetics. Detailed analyses of the isothermal thermogravimetric weight change data revealed that Cu-17%Cr exhibited parabolic oxidation kinetics with an activation energy of 165.9+/-9.5 kJ/mol. In contrast, the oxidation kinetics for the Cu-17%Cr-5%Al alloy exhibited a parabolic oxidation kinetics during the initial stages followed by a quartic relationship in the later stages of oxidation. Alternatively, the oxidation behavior of Cu-17%CR-5%Al could be better represented by a logarithmic relationship. The parabolic rate constants and activation energy data for the two alloys are compared with literature data to gain insights on the nature of the oxidation mechanisms dominant in these alloys.

  9. The effects of extinction, noncontingent reinforcement and differential reinforcement of other behavior as control procedures.

    OpenAIRE

    Thompson, Rachel H.; Iwata, Brian A.; Hanley, Gregory P; Dozier, Claudia L; Samaha, Andrew L

    2003-01-01

    Several techniques have been used in applied research as controls for the introduction of a reinforcement contingency, including extinction, noncontingent reinforcement (NCR), and differential reinforcement of other behavior (DRO). Little research, however, has examined the relative strengths and limitations of these "reversal" controls. We compared the effects of extinction with those of NCR and DRO in both multi-element and reversal designs, with respect to (a) rate and amount of response d...

  10. Evaluation of behavior of biodegradable lubricants in the differential sticking coefficient of water based drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, L.V. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais], E-mail: luciana@dem.ufcg.edu.br; Nascimento, R.C.A.M. [Universidade Federal de Campina Grande (PPGCEMat/UFCG), PB (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais; Lira, D.S. [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica; Magalhaes, J. [System Mud Fluidos de Perfuracao, Itajai, SC (Brazil). Dept. de Quimica

    2011-10-15

    This work aims to evaluate the behavior of four samples of biodegradable lubricants in the differential sticking coefficient of aqueous drilling fluids. Eighteen formulations of fluids containing bentonite clay, lubricants and biodegradable polymers in different concentrations were studied. The experiment focused on observing the samples' rheological properties, its filtration, the cake thickness, the lubricity coefficient, and, finally, the coefficient of the differential sticking. The results showed that the polymer additives improved rheological and filtration properties significantly. Also, the findings confirmed the idea that the presence of a lubricant leads to a reduction in lubricity, LC, and affects the differential sticking coefficient, DSC, of the fluids. However, the experiment observed a small variation on the LC as a result of an increase in the lubricant content. Overall, the results of the LC and the DSC of the fluids containing biodegradable lubricant additives were outstanding, being similar to the ones observed for oil-based fluids. (author)

  11. Separate and Combined Effects of Visual Schedules and Extinction Plus Differential Reinforcement on Problem Behavior Occasioned by Transitions

    Science.gov (United States)

    Waters, Melissa B.; Lerman, Dorothea C.; Hovanetz, Alyson N.

    2009-01-01

    The separate and combined effects of visual schedules and extinction plus differential reinforcement of other behavior (DRO) were evaluated to decrease transition-related problem behavior of 2 children diagnosed with autism. Visual schedules alone were ineffective in reducing problem behavior when transitioning from preferred to nonpreferred…

  12. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  13. Effect of Bi modification treatment on microstructure, tensile properties, and fracture behavior of cast Al-Mg2Si metal matrix composite

    Directory of Open Access Journals (Sweden)

    Wu Xiaofeng

    2013-01-01

    Full Text Available Bi has a good modification effect on the hypoeutectic Al-Si alloy, and the morphology of eutectic Si changes from coarse acicular to fine fibrous. Based on the similarity between Mg2Si and Si phases in crystalline structure and crystallization process, the present study investigated the effects of different concentrations of Bi on the microstructure, tensile properties, and fracture behavior of cast Al-15wt.%Mg2Si in-situ metal matrix composite. The results show that the addition of the proper amount of Bi has a significant modification effect on both primary and eutectic Mg2Si in the Al-15wt.%Mg2Si composite. With an increase in Bi content from 0 to 1wt.%, the morphology of the primary Mg2Si is changed from irregular or dendritic to polyhedral shape; and its average particle size is significantly decreased from 70 to 6 μm. Moreover, the morphology of the eutectic Mg2Si phase is altered from flake-like to very short fibrous or dot-like. When the Bi addition exceeds 4.0wt.%, the primary Mg2Si becomes coarse again. However, the eutectic Mg2Si still exhibits the modified morphology. Tensile tests reveal that the Bi addition can improve the tensile strength and ductility of the material. Compared with those of the unmodified composite, the ultimate tensile strength and percentage elongation after fracture with 1.0wt.% Bi increase 51.2% and 100%, respectively. At the same time, the Bi addition changes the fracture behavior from brittle to ductile.

  14. Particle motion behavior during gasification of foam carrier in lost foam-squeeze casting of 20%TiC/ZG270-500 composites

    Directory of Open Access Journals (Sweden)

    Bin Shibo

    2013-11-01

    Full Text Available The particle motion behavior affects the distribution of particles in the metal matrix and finally determines the mechanical properties of the particle reinforced metal-matrix composites. To obtain a uniform distribution of TiC particles and excellent strengthening effect in 20%TiC/ZG270-500 composites fabricated by lost foam-squeeze casting (LFSC, the particle motion behavior in the gas gap and the conditions of the particles getting into the molten steel were investigated. The results show that the airflow velocity (v1 and TiC particle motion velocity (uP change little with the pouring temperature (TP, increase with an increase in metal filling velocity (vP, ratios of cross sections of in-gate/orifice (AP/A0 and orifice/mould cavity (A0/A1, but the increase trend of uP is more intense. The airflow pressure (P1 changes little with TP and A0/A1, but increases with the increasing of vP and AP/A0. Besides, there is a critical velocity for the particles getting into the molten steel. The higher the particle motion velocity, the easier the particles get into the molten steel and the more uniform the distribution of the particles in the steel matrix. When TP = 1,873 K, vP = 30 mm·s-1, AP/A0 =10 and A0/A1 = 0.02 in this study, the biggest TiC particle motion velocity (20.59 m·s-1 can be gained, and the steel matrix with the most uniformly distributed TiC particles and fine grains are obtained.

  15. The ancient Chinese casting techniques

    OpenAIRE

    2011-01-01

    In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast ir...

  16. Thin Wall Iron Castings

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  17. Differential behavioral sensitivity to carbon dioxide (CO2) inhalation in rats.

    Science.gov (United States)

    Winter, Andrew; Ahlbrand, Rebecca; Naik, Devanshi; Sah, Renu

    2017-03-27

    Inhalation of carbon dioxide (CO2) is frequently employed as a biological challenge to evoke intense fear and anxiety. In individuals with panic disorder, CO2 reliably evokes panic attacks. Sensitivity to CO2 is highly heterogeneous among individuals, and although a genetic component is implicated, underlying mechanisms are not clear. Preclinical models that can simulate differential responsivity to CO2 are therefore relevant. In the current study we investigated CO2-evoked behavioral responses in four different rat strains: Sprague-Dawley (SD), Wistar (W), Long Evans (LE) and Wistar-Kyoto, (WK) rats. We also assessed tryptophan hydroxylase 2 (TPH-2)-positive serotonergic neurons in anxiety/panic regulatory subdivisions of the dorsal raphe nucleus (DR), as well as dopamine β hydroxylase (DβH)-positive noradrenergic neurons in the locus coeruleus, implicated in central CO2-chemosensitivity. Behavioral responsivity to CO2 inhalation varied between strains. CO2-evoked immobility was significantly higher in LE and WK rats as compared with W and SD cohorts. Differences were also observed in CO2-evoked rearing and grooming behaviors. Exposure to CO2 did not produce conditioned behavioral responses upon re-exposure to CO2 context in any strain. Reduced TPH-2-positive cell counts were observed specifically in the panic-regulatory dorsal raphe ventrolateral (DRVL)-ventrolateral periaqueductal gray (VLPAG) subdivision in CO2-sensitive strains. Conversely, DβH-positive cell counts within the LC were significantly higher in CO2-sensitive strains. Collectively, our data provide evidence for strain dependent, differential CO2-sensitivity and potential differences in monoaminergic systems regulating panic and anxiety. Comparative studies between CO2-vulnerable and resistant strains may facilitate the mechanistic understanding of differential CO2-sensitivity in the development of panic and anxiety disorders.

  18. SEPARATE AND COMBINED EFFECTS OF VISUAL SCHEDULES AND EXTINCTION PLUS DIFFERENTIAL REINFORCEMENT ON PROBLEM BEHAVIOR OCCASIONED BY TRANSITIONS

    OpenAIRE

    Waters, Melissa B; Lerman, Dorothea C; Hovanetz, Alyson N

    2009-01-01

    The separate and combined effects of visual schedules and extinction plus differential reinforcement of other behavior (DRO) were evaluated to decrease transition-related problem behavior of 2 children diagnosed with autism. Visual schedules alone were ineffective in reducing problem behavior when transitioning from preferred to nonpreferred activities. Problem behavior decreased for both participants when extinction and DRO were introduced, regardless of whether visual schedules were also used.

  19. Understanding of the influence of process parameters on the heat transfer behavior at the metal/die inter-face in high pressure die casting process

    Institute of Scientific and Technical Information of China (English)

    GUO ZhiPeng; XIONG ShouMei; LIU BaiCheng; LI Mei; Allison John

    2009-01-01

    The current paper focuses on the influence of the process parameters on the peak values of the inter-facial heat transfer coefficient (IHTC) at metal/die interface during high pressure die casting (HPDC) process. A "step shape" casting and AM50 alloy were used during the experiment. The IHTC was de-termined by solving the inverse thermal problem based on the measured temperature inside the die. Results show that the initial die surface temperature (IDST, TDI) has a dominant influence while the casting pressure and fast shot velocity have a secondary influence on the IHTC peak values. By curve fitting, it was found that the IHTC peak value (hmax) changes as a function of the IDST in a manner of hmax=eαTγDI. Such relationship between the IHTC peak value and the IDST can also be found when the casting alloy is ADC12, indicating that this phenomenon is a common characteristic in the HPDC process.

  20. Differential regulation of the foraging gene associated with task behaviors in harvester ants

    Directory of Open Access Journals (Sweden)

    Kleeman Lindsay

    2011-08-01

    Full Text Available Abstract Background The division of labor in social insect colonies involves transitions by workers from one task to another and is critical to the organization and ecological success of colonies. The differential regulation of genetic pathways is likely to be a key mechanism involved in plasticity of social insect task behavior. One of the few pathways implicated in social organization involves the cGMP-activated protein kinase gene, foraging, a gene associated with foraging behavior in social insect species. The association of the foraging gene with behavior is conserved across diverse species, but the observed expression patterns and proposed functions of this gene vary across taxa. We compared the protein sequence of foraging across social insects and explored whether the differential regulation of this gene is associated with task behaviors in the harvester ant, Pogonomyrmex occidentalis. Results Phylogenetic analysis of the coding region of the foraging gene reveals considerable conservation in protein sequence across insects, particularly among hymenopteran species. The absence of amino acid variation in key active and binding sites suggests that differences in behaviors associated with this gene among species may be the result of changes in gene expression rather than gene divergence. Using real time qPCR analyses with a harvester ant ortholog to foraging (Pofor, we found that the brains of harvester ant foragers have a daily fluctuation in expression of foraging with mRNA levels peaking at midday. In contrast, young workers inside the nest have low levels of Pofor mRNA with no evidence of daily fluctuations in expression. As a result, the association of foraging expression with task behavior within a species changes depending on the time of day the individuals are sampled. Conclusions The amino acid protein sequence of foraging is highly conserved across social insects. Differences in foraging behaviors associated with this gene among

  1. Standard digital reference images for titanium castings

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 The digital reference images provided in the adjunct to this standard illustrate various types and degrees of discontinuities occurring in titanium castings. Use of this standard for the specification or grading of castings requires procurement of the adjunct digital reference images, which illustrate the discontinuity types and severity levels. They are intended to provide the following: 1.1.1 A guide enabling recognition of titanium casting discontinuities and their differentiation both as to type and degree through digital radiographic examination. 1.1.2 Example digital radiographic illustrations of discontinuities and a nomenclature for reference in acceptance standards, specifications and drawings. 1.2 The digital reference images consist of seventeen digital files each illustrating eight grades of increasing severity. The files illustrate seven common discontinuity types representing casting sections up to 1-in. (25.4-mm). 1.3 The reference radiographs were developed for casting sections up to 1...

  2. Use of differential reinforcement to reduce behavior problems in adults with intellectual disabilities: a methodological review.

    Science.gov (United States)

    Chowdhury, Monali; Benson, Betsey A

    2011-01-01

    The least-restrictive-alternative guideline for providing treatment emphasizes the use of non-aversive procedures to reduce maladaptive behaviors in individuals with intellectual disability (ID). Differential reinforcement (DR) is an excellent example of such a non-aversive, reinforcement based behavioral intervention. The purpose of this literature review was to summarize and provide a methodological analysis of studies, conducted between 1980 and 2009, using a DR contingency to reduce problem behaviors in adults with ID. A total of 31 studies were located that met the inclusion criteria. Of these, 15 reported DR to be an effective intervention when used independently. Of the remaining, 10 studies found DR to be useful as part of a treatment package, and six found a DR contingency used independently to be ineffective, and only observed treatment effects when an aversive component was added. Very few studies assessed the use of DR in older adults and in individuals with mild ID; these reflect areas of future research. A methodological analysis found that several studies did not report information on key methodological variables; for example, conducting a functional analysis and a stimulus preference assessment to guide choice of treatment and reinforcers, thinning very dense DR schedules, assessing collateral behaviors, generalization of behavior change across settings and implementers, and following up treatment outcomes over time. The overall positive findings about the effectiveness of DR are encouraging; however, more methodologically robust studies would serve to make such findings more conclusive and practically relevant for implementation in natural settings for adults with ID.

  3. Tensile Properties and Fracture Behavior of Aluminum Alloy Foam Fabricated from Die Castings without Using Blowing Agent by Friction Stir Processing Route

    Directory of Open Access Journals (Sweden)

    Yoshihiko Hangai

    2014-03-01

    Full Text Available Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%–78% were fabricated from Al alloy die castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis.

  4. Determinação das castas em Scaptotrigona postica (Latreille (Hymenoptera, Apidae, Meliponini: diferenciação do ovário Caste determination in Scaptotrigona postica (Latreille (Hymenoptera, Apidae, Meliponini: the ovarian differentiation

    Directory of Open Access Journals (Sweden)

    Thaís da Cruz Alves dos Santos

    2002-09-01

    Full Text Available Both castes of Scaptotrigolia postica (Latreille, 1804 possess four ovarioles in each ovary. Queen and workers have the same ovarian development during the larvallife, but in lhe late larval stage the queen ovary beco me larger. During pupation a higher rate of cell division is observed in queen ovarioles and a higher rale of cell death in workers. Newly emerged workers have short ovarioles with differenriatcd germarium and vitellarium while queens have very long ovarioles with only germarium. Caste deterrnination in rhis species of bee is trophic, but lhe food does not differ in quality, only in quantiry. The food differences only beco me effecri ve by the end of larval stage when the queen larvae have lhe opportunity of eat more. In this way lhe ovary differentiation, between workers and queens. In this species, only occurs frorn lhe end of larval stage, mainly during pupation. Although the ovaries of workers are smaller, they are precocious in relation to queens, since nurse workers, 5 10 20 days, old may lay eggs. The eggs laid by the workers may be trophic or functional. These eggs may be distinguished by lhe aspect ofthe yolk. Older forager workers have degenerated ovaries.

  5. Asymptotic behavior of solutions for some nonlinear partial differential equations on unbounded domains

    Directory of Open Access Journals (Sweden)

    Jacqueline Fleckinger

    2001-12-01

    Full Text Available We study the asymptotic behavior of positive solutions $u$ of $$ -Delta_p u(x = V(x u(x^{p-1}, quad p>1; x in Omega,$$ and related partial differential inequalities, as well as conditions for existence of such solutions. Here, $Omega$ contains the exterior of a ball in $mathbb{R}^N$ $1

  6. The effects of extinction, noncontingent reinforcement and differential reinforcement of other behavior as control procedures.

    Science.gov (United States)

    Thompson, Rachel H; Iwata, Brian A; Hanley, Gregory P; Dozier, Claudia L; Samaha, Andrew L

    2003-01-01

    Several techniques have been used in applied research as controls for the introduction of a reinforcement contingency, including extinction, noncontingent reinforcement (NCR), and differential reinforcement of other behavior (DRO). Little research, however, has examined the relative strengths and limitations of these "reversal" controls. We compared the effects of extinction with those of NCR and DRO in both multi-element and reversal designs, with respect to (a) rate and amount of response decrement, (b) rate of response recovery following reintroduction of reinforcement, and (c) any positive or negative side effects associated with transitions. Results indicated that extinction generally produced the most consistent and rapid reversal effects, with few observed negative side effects.

  7. Emergent user behavior on Twitter modelled by a stochastic differential equation.

    Science.gov (United States)

    Mollgaard, Anders; Mathiesen, Joachim

    2015-01-01

    Data from the social-media site, Twitter, is used to study the fluctuations in tweet rates of brand names. The tweet rates are the result of a strongly correlated user behavior, which leads to bursty collective dynamics with a characteristic 1/f noise. Here we use the aggregated "user interest" in a brand name to model collective human dynamics by a stochastic differential equation with multiplicative noise. The model is supported by a detailed analysis of the tweet rate fluctuations and it reproduces both the exact bursty dynamics found in the data and the 1/f noise.

  8. Emergent user behavior on Twitter modelled by a stochastic differential equation

    CERN Document Server

    Mollgaard, Anders

    2015-01-01

    Data from the social-media site, Twitter, is used to study the fluctuations in tweet rates of brand names. The tweet rates are the result of a strongly correlated user behavior, which leads to bursty collective dynamics with a characteristic 1/f noise. Here we use the aggregated "user interest" in a brand name to model collective human dynamics by a stochastic differential equation with multiplicative noise. The model is supported by a detailed analysis of the tweet rate fluctuations and it reproduces both the exact bursty dynamics found in the data and the 1/f noise.

  9. Emergent user behavior on Twitter modelled by a stochastic differential equation.

    Directory of Open Access Journals (Sweden)

    Anders Mollgaard

    Full Text Available Data from the social-media site, Twitter, is used to study the fluctuations in tweet rates of brand names. The tweet rates are the result of a strongly correlated user behavior, which leads to bursty collective dynamics with a characteristic 1/f noise. Here we use the aggregated "user interest" in a brand name to model collective human dynamics by a stochastic differential equation with multiplicative noise. The model is supported by a detailed analysis of the tweet rate fluctuations and it reproduces both the exact bursty dynamics found in the data and the 1/f noise.

  10. Reduction of biting and chewing of horses using differential reinforcement of other behavior.

    Science.gov (United States)

    Fox, Adam E; Bailey, Shana R; Hall, Ezra G; St Peter, Claire C

    2012-09-01

    Biting and chewing by horses on crossties can result in injury to the handler and damage to equipment. Operant-conditioning techniques have been used to train horses and could be used to reduce or eliminate undesirable biting and chewing. Presently, a differential-reinforcement-of-other-behavior (DRO) schedule, in the context of a reversal design, was effective in reducing biting and chewing in two horses. In DRO schedules, a reinforcer is delivered contingent on the absence of a target behavior for a specified interval. Positive-reinforcement procedures offer an alternative to aversive-control techniques typically used in equine training and may provide for better equine welfare and horse-human interaction.

  11. Tachykinin expression levels correlate with caste-specific aggression in workers of the leaf-cutting ant Acromyrmex echinatior

    DEFF Research Database (Denmark)

    Howe, Jack; Schiøtt, Morten; Boomsma, Jacobus Jan

    2016-01-01

    of neurons was recently shown to determine the stimulus response threshold for aggressive behavior in Drosophila (1). Varying response thresholds are often implicated in division of labor within social insect colonies, so we hypothesized that Tachykinin could play a role in the organization of colony defense...... results for the reproductive caste, we manipulated the aggression threshold of virgin-queens by removing their wings, which is known to make them express a soldier-like behavioral phenotype. Despite heightened aggression, expression levels of Tachykinin remained unaffected, suggesting that aggression...... levels in reproductive caste phenotypes are controlled by differential expression of other genes....

  12. Sexual differentiation of human behavior: effects of prenatal and pubertal organizational hormones.

    Science.gov (United States)

    Berenbaum, Sheri A; Beltz, Adriene M

    2011-04-01

    A key question concerns the extent to which sexual differentiation of human behavior is influenced by sex hormones present during sensitive periods of development (organizational effects), as occurs in other mammalian species. The most important sensitive period has been considered to be prenatal, but there is increasing attention to puberty as another organizational period, with the possibility of decreasing sensitivity to sex hormones across the pubertal transition. In this paper, we review evidence that sex hormones present during the prenatal and pubertal periods produce permanent changes to behavior. There is good evidence that exposure to high levels of androgens during prenatal development results in masculinization of activity and occupational interests, sexual orientation, and some spatial abilities; prenatal androgens have a smaller effect on gender identity, and there is insufficient information about androgen effects on sex-linked behavior problems. There is little good evidence regarding long-lasting behavioral effects of pubertal hormones, but there is some suggestion that they influence gender identity and perhaps some sex-linked forms of psychopathology, and there are many opportunities to study this issue.

  13. Exploring behaviors of stochastic differential equation models of biological systems using change of measures

    Directory of Open Access Journals (Sweden)

    Jha Sumit

    2012-04-01

    Full Text Available Abstract Stochastic Differential Equations (SDE are often used to model the stochastic dynamics of biological systems. Unfortunately, rare but biologically interesting behaviors (e.g., oncogenesis can be difficult to observe in stochastic models. Consequently, the analysis of behaviors of SDE models using numerical simulations can be challenging. We introduce a method for solving the following problem: given a SDE model and a high-level behavioral specification about the dynamics of the model, algorithmically decide whether the model satisfies the specification. While there are a number of techniques for addressing this problem for discrete-state stochastic models, the analysis of SDE and other continuous-state models has received less attention. Our proposed solution uses a combination of Bayesian sequential hypothesis testing, non-identically distributed samples, and Girsanov's theorem for change of measures to examine rare behaviors. We use our algorithm to analyze two SDE models of tumor dynamics. Our use of non-identically distributed samples sampling contributes to the state of the art in statistical verification and model checking of stochastic models by providing an effective means for exposing rare events in SDEs, while retaining the ability to compute bounds on the probability that those events occur.

  14. Exploring behaviors of stochastic differential equation models of biological systems using change of measures.

    Science.gov (United States)

    Jha, Sumit Kumar; Langmead, Christopher James

    2012-04-12

    Stochastic Differential Equations (SDE) are often used to model the stochastic dynamics of biological systems. Unfortunately, rare but biologically interesting behaviors (e.g., oncogenesis) can be difficult to observe in stochastic models. Consequently, the analysis of behaviors of SDE models using numerical simulations can be challenging. We introduce a method for solving the following problem: given a SDE model and a high-level behavioral specification about the dynamics of the model, algorithmically decide whether the model satisfies the specification. While there are a number of techniques for addressing this problem for discrete-state stochastic models, the analysis of SDE and other continuous-state models has received less attention. Our proposed solution uses a combination of Bayesian sequential hypothesis testing, non-identically distributed samples, and Girsanov's theorem for change of measures to examine rare behaviors. We use our algorithm to analyze two SDE models of tumor dynamics. Our use of non-identically distributed samples sampling contributes to the state of the art in statistical verification and model checking of stochastic models by providing an effective means for exposing rare events in SDEs, while retaining the ability to compute bounds on the probability that those events occur.

  15. Social Differentiation in Common Bottlenose Dolphins (Tursiops truncatus) that Engage in Human-Related Foraging Behaviors.

    Science.gov (United States)

    Kovacs, Carolyn J; Perrtree, Robin M; Cox, Tara M

    2017-01-01

    Both natural and human-related foraging strategies by the common bottlenose dolphin (Tursiops truncatus) have resulted in social segregation in several areas of the world. Bottlenose dolphins near Savannah, Georgia beg at an unprecedented rate and also forage behind commercial shrimp trawlers, providing an opportunity to study the social ramifications of two human-related foraging behaviors within the same group of animals. Dolphins were photo-identified via surveys conducted throughout estuarine waterways around Savannah in the summers of 2009-2011. Mean half-weight indices (HWI) were calculated for each foraging class, and community division by modularity was used to cluster animals based on association indices. Pairs of trawler dolphins had a higher mean HWI (0.20 ± 0.07) than pairs of non-trawler dolphins (0.04 ± 0.02) or mixed pairs (0.02 ± 0.02). In contrast, pairs of beggars, non-beggars, and mixed pairs all had similar means, with HWI between 0.05-0.07. Community division by modularity produced a useful division (0.307) with 6 clusters. Clusters were predominately divided according to trawler status; however, beggars and non-beggars were mixed throughout clusters. Both the mean HWI and social clusters revealed that the social structure of common bottlenose dolphins near Savannah, Georgia was differentiated based on trawler status but not beg status. This finding may indicate that foraging in association with trawlers is a socially learned behavior, while the mechanisms for the propagation of begging are less clear. This study highlights the importance of taking into account the social parameters of a foraging behavior, such as how group size or competition for resources may affect how the behavior spreads. The positive or negative ramifications of homophily may influence whether the behaviors are exhibited by individuals within the same social clusters and should be considered in future studies examining social relationships and foraging behaviors.

  16. Hot Extrusion Process Effect on Mechanical Behavior of Stir Cast Al Based Composites Reinforced with Mechanically Milled B4C Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    A. Alizadeh1; E. Taheri-Nassaj; M. Hajizamani

    2011-01-01

    In this study, aluminum alloy (Al-2 wt% Cu) matrix composites reinforced with 1, 2 and 4 wt% boron carbide nanoparticles fabricated through mechanical milling with average size of 100 nm were fabricated via stir casting method at 850℃. Cast ingots of the matrix alloy and the composites were extruded at 500℃ at an extrusion ratio of 10:1 to investigate the effects of hot extrusion on the mechanical properties of the composites. The microstructures of the as-cast and the extruded composites were investigated by scanning electron microscopy (SEM). Density measurement, hardness and tensile tests were carried out to identify the mechanical properties of the composites. The extruded samples revealed a more uniform distribution of B4C nanoparticles. Also, the extruded samples had strength and ductility values superior to those of the as-cast counterparts. In the as-cast and the extruded samples, with increasing amount of B4C nanoparticles, yield strength and tensile strength increased but elongation to fracture decreased.

  17. Research data supporting "Differentiation of online text-based advertising and the effect on users’ click behavior"

    OpenAIRE

    Jacques, Jason T.; Kristensson, Per Ola

    2015-01-01

    Click data for "Differentiation of Online Text-based Advertising and the Effect on Users’ Click Behavior" as published in "Computers in Human Behavior" (http://dx.doi.org/10.1016/j.chb.2015.04.031) This work was supported by the Engineering and Physical Research Council [DTA]. ESPRC

  18. An educational multimedia campaign has differential effects on public stroke knowledge and care-seeking behavior.

    Science.gov (United States)

    Marx, Juergen J; Nedelmann, Max; Haertle, Birgit; Dieterich, Marianne; Eicke, Bernd M

    2008-03-01

    To study the differential educational effects of a multimodal educational program on public stroke knowledge, we performed computer-assisted telephone surveys among a random sample of 500 members of the general public, before and immediately after an intense three-month educational campaign. The intervention comprised of poster advertisements, flyers, mail circular, slogans, stroke interest stories etc. in local newspapers, on television and radio, and public events. The main outcome measures were stroke knowledge, the intended behavior in acute stroke and the educational media remembered after the intervention. General knowledge of the nature of stroke (65.7% correct answers before versus 84.9 % after the campaign, p differential effects on public stroke knowledge and individual stroke risk,which does not necessarily lead to a change in care-seeking behavior. Repeated information using short-tailored slogans and cues to action led to a gain in general stroke knowledge, especially in high-risk populations of lower educational background. Large educational campaigns seem unsuitable, however, for mediation of detailed information on stroke.

  19. LLNL casting technology

    Science.gov (United States)

    Shapiro, A. B.; Comfort, W. J., III

    1994-01-01

    Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

  20. PHYSICAL SIMULATION OF CONTINUOUS ROLL CASTING PROCESS

    Institute of Scientific and Technical Information of China (English)

    L.H. Zhan; J. Zhong; X.Q. Li; M.H. Huang

    2005-01-01

    A series of simulating experimental studies on the rheological behavior and its influential factors of aluminum alloy in continuous roll-casting process have been explored in this paper with a Gleeble-1500 Thermal-Mechanical Simulation Tester and a set of special clamp system. Relevant rheological rules in the process of coupling transient solidification and continuous deformation of roll-casting conditions are obtained. Experimental results indicate that four different characteristic stages exist in the whole rheological process, and relative constitutive models suitable for the given conditions of continuous roll casting process have been established through multivariable linear regression analysis of the experimental data.

  1. Differential genetic and environmental influences on developmental trajectories of antisocial behavior from adolescence to young adulthood.

    Science.gov (United States)

    Zheng, Yao; Cleveland, H Harrington

    2015-12-01

    Little research has investigated differential genetic and environmental influences on different developmental trajectories of antisocial behavior. This study examined genetic and environmental influences on liabilities of being in life-course-persistent (LCP) and adolescent-limited (AL) type delinquent groups from adolescence to young adulthood while considering nonviolent and violent delinquency subtypes and gender differences. A genetically informative sample (n = 356, 15-16 years) from the first three waves of In-Home Interview of the National Longitudinal Study of Adolescent to Adult Health was used, with 94 monozygotic and 84 dizygotic pairs of same-sex twins (50% male). Biometric liability threshold models were fit and found that the male-specific LCP type class, chronic, showed more genetic influences, while the AL type classes, decliner and desister, showed more environmental influences. Genetic liability and shared environment both influence the persistence of antisocial behavior. The development of female antisocial behavior appears to be influenced more by shared environment.

  2. Differential effects of endomorphin-1 and -2 on amphetamine sensitization: neurochemical and behavioral aspects.

    Science.gov (United States)

    Chen, J C; Liang, K W; Huang, E Y

    2001-03-01

    Mu-opioid receptors are known to modulate mesolimbic dopaminergic activity in the ventral tegmental area via disinhibition of GABA-containing neurons. Recently, two novel tetrapeptides, endomorphin-1 and endomorphin-2, were identified in the mammalian brain and reported to have high binding affinities toward mu-opioid receptors. To determine if endomorphins would modulate the development of amphetamine sensitization, we administered endomorphins locally into the rat brain followed by behavioral and neurochemical examinations. The results indicate that rats pretreated with endomorphin-1 or -2 (5 microg per side for 7 days) in the ventral tegmental area developed locomotor sensitization to the challenge injection of amphetamine (1 mg/kg). On the other hand, when endomorphins were given in the lateral ventricle (20 microg for 5 days) of amphetamine-sensitized rats (5 mg/kg x 14 days) during the withdrawal period (w5-w9), neither peptide had a modulatory effect on locomotor sensitization. Biochemical analyses revealed that treatment with endomorphins in the ventral tegmental area significantly increased the levels of glutamate in the medial prefrontal cortex and ventral and dorsal striatum to levels comparable to those observed in the amphetamine-sensitized rats. In the same animals, endomorphins also caused decreases in the levels of serotonin and its metabolite, 5-hydroxyindoleacetic acid, in the medial prefrontal cortex. Interestingly, although there was no behavioral significance, endomorphin-1 treatment in the lateral ventricle of control and amphetamine-sensitized rats during withdrawal resulted in decreases of GABA, aspartate, dopamine, and its metabolite 3,4-dihydroxyphenylacetic acid in the ventral striatum. We conclude that endomorphins, by stimulating the mu-opioid receptors in the ventral tegmental area, could sensitize the behavioral response to amphetamine. The results also demonstrate that there are differential responses between endomorphin-1 and -2 on

  3. Diet, age, and prior injury status differentially alter behavioral outcomes following concussion in rats.

    Science.gov (United States)

    Mychasiuk, Richelle; Hehar, Harleen; van Waes, Linda; Esser, Michael J

    2015-01-01

    Mild traumatic brain injury (mTBI) or concussion affects a large portion of the population and although many of these individuals recover completely, a small subset of people experience lingering symptomology and poor outcomes. Little is known about the factors that affect individual susceptibility or resilience to poor outcomes after mTBI and there are currently no biomarkers to delineate mTBI diagnosis or prognosis. Based upon the growing literature associated with caloric intake and altered neurological aging and the ambiguous link between repetitive mTBI and progressive neurodegeneration, the current study was designed to examine the effect of a high fat diet (HFD), developmental age, and repetitive mTBI on behavioral outcomes following a mTBI. In addition, telomere length was examined before and after experimental mTBI. Sprague Dawley rats were maintained on a HFD or standard rat chow throughout life (including the prenatal period) and then experienced an mTBI/concussion at P30, P30 and P60, or only at P60. Behavioral outcomes were examined using a test battery that was administered between P61-P80 and included; beam-walking, open field, elevated plus maze, novel context mismatch, Morris water task, and forced swim task. Animals with a P30 mTBI often demonstrated lingering symptomology that was still present during testing at P80. Injuries at P30 and P60 rarely produced cumulative effects, and in some tests (i.e., beam walking), the first injury may have protected the brain from the second injury. Exposure to the high fat diet exacerbated many of the behavioral deficits associated with concussion. Finally, telomere length was shortened following mTBI and was influenced by the animal's dietary intake. Diet, age at the time of injury, and the number of prior concussion incidents differentially contribute to behavioral deficits and may help explain individual variations in susceptibility and resilience to poor outcomes following an mTBI.

  4. Behavioral differentiation of mice exposed to a water tank social interaction test.

    Science.gov (United States)

    Nejdi, A; Guastavino, J M; Lalonde, R; Desor, D; Krafft, B

    1996-02-01

    Male or female C57BL/6J mice were exposed to a water tank in which food could be obtained only by wading in the water towards a feeder. Behavioral differentiation occurred in that three distinct categories could be distinguished: major carriers (transporting over 80% of the food pellets), sporadic carriers (transporting less than 20% of the food pellets) and non-carriers. In the elevated + -maze, major carriers were more willing to explore open spaces than non-carriers. Sporadic carriers showed some evidence of the same tendency of decreased anxiety, but in a minor way. The willingness of mice to become carriers is associated with their willingness to explore novel areas. This test may be useful for the assessment of anxiolytic compounds in a social situation.

  5. Lipschitz regularity for integro-differential equations with coercive Hamiltonians and application to large time behavior

    Science.gov (United States)

    Barles, Guy; Ley, Olivier; Topp, Erwin

    2017-02-01

    In this paper, we provide suitable adaptations of the ‘weak version of Bernstein method’ introduced by the first author in 1991, in order to obtain Lipschitz regularity results and Lipschitz estimates for nonlinear integro-differential elliptic and parabolic equations set in the whole space. Our interest is to obtain such Lipschitz results to possibly degenerate equations, or to equations which are indeed ‘uniformly elliptic’ (maybe in the nonlocal sense) but which do not satisfy the usual ‘growth condition’ on the gradient term allowing to use (for example) the Ishii-Lions’ method. We treat the case of a model equation with a superlinear coercivity on the gradient term which has a leading role in the equation. This regularity result together with comparison principle provided for the problem allow to obtain the ergodic large time behavior of the evolution problem in the periodic setting.

  6. Behavioral analysis of differential Hebbian learning in closed-loop systems

    DEFF Research Database (Denmark)

    Kulvicius, Tomas; Kolodziejski, Christoph; Tamosiunaite, Minija;

    2010-01-01

    measuring information of inputs. In this study we analyze a specific type of closed loop system by looking at the input as well as the output space. For this, we investigate simulated agents that perform differential Hebbian learning (STDP). In the first part we show that analytical solutions can be found......Understanding closed loop behavioral systems is a non-trivial problem, especially when they change during learning. Descriptions of closed loop systems in terms of information theory date back to the 1950s, however, there have been only a few attempts which take into account learning, mostly...... for the temporal development of such systems for relatively simple cases. In the second part of this study we try to answer the following question: How can we predict which system from a given class would be the best for a particular scenario? This question is addressed using energy, input/output ratio and entropy...

  7. Adolescent behavioral and neural reward sensitivity: a test of the differential susceptibility theory

    Science.gov (United States)

    Richards, J S; Arias Vásquez, A; von Rhein, D; van der Meer, D; Franke, B; Hoekstra, P J; Heslenfeld, D J; Oosterlaan, J; Faraone, S V; Buitelaar, J K; Hartman, C A

    2016-01-01

    Little is known about the causes of individual differences in reward sensitivity. We investigated gene–environment interactions (GxE) on behavioral and neural measures of reward sensitivity, in light of the differential susceptibility theory. This theory states that individuals carrying plasticity gene variants will be more disadvantaged in negative, but more advantaged in positive environments. Reward responses were assessed during a monetary incentive delay task in 178 participants with and 265 without attention-deficit/hyperactivity disorder (ADHD), from N=261 families. We examined interactions between variants in candidate plasticity genes (DAT1, 5-HTT and DRD4) and social environments (maternal expressed emotion and peer affiliation). HTTLPR short allele carriers showed the least reward speeding when exposed to high positive peer affiliation, but the most when faced with low positive peer affiliation or low maternal warmth. DAT1 10-repeat homozygotes displayed similar GxE patterns toward maternal warmth on general task performance. At the neural level, DRD4 7-repeat carriers showed the least striatal activation during reward anticipation when exposed to high maternal warmth, but the most when exposed to low warmth. Findings were independent of ADHD severity. Our results partially confirm the differential susceptibility theory and indicate the importance of positive social environments in reward sensitivity and general task performance for persons with specific genotypes. PMID:27045841

  8. Metallic Fuel Casting Development and Parameter Optimization Simulations

    Energy Technology Data Exchange (ETDEWEB)

    R.S. Fielding; J. Crapps; C. Unal; J.R. Kennedy

    2013-03-01

    One of the advantages of metallic fuel is the abilility to cast the fuel slugs to near net shape with little additional processing. However, the high aspect ratio of the fuel is not ideal for casting. EBR-II fuel was cast using counter gravity injection casting (CGIC) but, concerns have been raised concerning the feasibility of this process for americium bearing alloys. The Fuel Cycle Research and Development program has begun developing gravity casting techniques suitable for fuel production. Compared to CGIC gravity casting does not require a large heel that then is recycled, does not require application of a vacuum during melting, and is conducive to re-usable molds. Development has included fabrication of two separate benchscale, approximately 300 grams, systems. To shorten development time computer simulations have been used to ensure mold and crucible designs are feasible and to identify which fluid properties most affect casting behavior and therefore require more characterization.

  9. Simultaneous Characterization for the Organic Additive Burnout of Aqueous Tape Casting Aluminum Nitride by Thermogravimetry-Differential Scanning Calorimetry-Mass Spectrometry%水基AlN流延膜有机添加剂排胶过程的热重-差示扫描热量-质谱研究

    Institute of Scientific and Technical Information of China (English)

    于惠梅; 雒晓军; 陆昌伟; 奚同庚; 罗澜

    2004-01-01

    In this work, through the comparison analysis with the results of the thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS) coupling techniques for the three organic additive and aqueous tape casting aluminum nitride in air and nitrogen atmosphere, it can be found that the plasticity glycerol was almost burnout before 350℃ in two atmosphere; the binder PVA124 was almost burnout before 600℃ in air, there was little left in nitrogen; The mass losses of the dispersant DP270 in air and nitrogen atmosphere were about 73.32% and 65.51% before 600℃ ; The mass losses of the aqueous tape casting aluminum nitride in air (14.08%) were higher that in nitrogen (10.75%) before 600℃. It can be concluded that the organic additive burnout of the aqueous tape casting aluminum nitride in air atmosohere was better than in nitrogen atmosphere.

  10. Negative parenting behavior and childhood oppositional defiant disorder: differential moderation by positive and negative peer regard.

    Science.gov (United States)

    Tung, Irene; Lee, Steve S

    2014-01-01

    Although negative parenting behavior and peer status are independently associated with childhood conduct problems (e.g., oppositional defiant disorder (ODD)), relatively little is known about their interplay, particularly in relation to differentiated measures of positive and negative peer regard. To improve the specificity of the association of negative parenting behavior and peer factors with ODD, we explored the potential interaction of parenting and peer status in a sample of 169 five-to ten-year-old ethnically diverse children with and without attention-deficit/hyperactivity disorder (ADHD) assessed using multiple measures (i.e., rating scales, interview) and informants (i.e., parents, teachers). Controlling for children's age, sex, number of ADHD symptoms, and parents' race-ethnicity, peer acceptance inversely predicted and inconsistent discipline, harsh punishment, and peer rejection were each positively associated with ODD symptom severity. Interactive influences were also evident such that inconsistent discipline and harsh punishment each predicted elevated ODD but only among children experiencing low peer acceptance or high peer rejection. These findings suggest that supportive environments, including peer acceptance, may protect children from negative outcomes associated with inconsistent discipline and harsh punishment. Findings are integrated with theories of social support, and we additionally consider implications for intervention and prevention.

  11. Differential drug effects on spontaneous and evoked pain behavior in a model of trigeminal neuropathic pain

    Science.gov (United States)

    Deseure, K; Hans, GH

    2017-01-01

    Purpose Baclofen and morphine have shown efficacy against mechanical allodynia after infraorbital nerve chronic constriction injury (IoN-CCI). No drug effects have yet been reported on spontaneous trigeminal neuropathic pain. It has been proposed that the directed face grooming behavior that also develops following IoN-CCI offers a measure of spontaneous trigeminal neuropathic pain. Subjects and methods We examined the effects of a continuous 1-week infusion of 30 mg/day carbamazepine (the first-line drug treatment for trigeminal neuralgia), 1.06 mg/day baclofen, 4.18 mg/day clomipramine, and 5 mg/day morphine on spontaneous and mechanically evoked pain behavior (ie, directed face grooming and von Frey testing) in IoN-CCI rats. Results Isolated face grooming was significantly reduced in rats receiving carbamazepine and baclofen but not in clomipramine- or morphine-treated rats. All drugs showed significant antiallodynic effects; carbamazepine showed the strongest effects, whereas clomipramine had only minor efficacy. Conclusion The tested drugs have differential effects in the IoN-CCI model, and different neuropathological mechanisms may underlie the different somatosensory symptoms in this model. A mechanism-based approach may be needed to treat (trigeminal) neuropathic pain. The present data support IoN-CCI as a model of trigeminal neuralgia in which isolated face grooming is used as a measure of spontaneous neuropathic pain. PMID:28184169

  12. Mechanical behavior of cast SiC{sub p}-reinforced Al-4.5%Cu-1.5%Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Skolianos, S. [Aristoteles Univ., Thessaloniki (Greece)

    1996-06-15

    SiC{sub p}-reinforced Al-4.5%Cu-1.5%Mg composite specimens were processed by vigorous stirring of the carbide in a semi-solid alloy slurry, followed by remelting and casting (stir-casting). The tensile and fatigue properties were evaluated in the as-cast and in the heat-treated conditions. In monotonic tensile testing, reinforcement with SiC{sub p} produced a substantial increase in the work hardening of the material. This increase became more significant with increasing volume fraction of carbide. The yield and ultimate tensile strength, and the elastic modulus of the material, increased with heat-treatment and volume fraction of carbide at the expense of ductility. These properties are inferior to those of other reinforced, more complex aluminum alloys processed by other methods. In stress-controlled fatigue tests under fully reversed (R=-1) bending conditions, the fatigue life of the composite was longer than that of the unreinforced specimen at intermediate and lower stress levels. At higher stress levels the improvement was negligible. In heat-treated reinforced alloy specimens the fatigue strength at 1.10{sup 7} cycles decreased with increasing carbide particle size. With solid solution and precipitation strengthening, as well as carbide dispersion strengthening of the alloy, the crack growth threshold stress intensity factor K{sub th}, increased, as did the crack initiation time and the crack growth rate. (orig.)

  13. Glovebox Advanced Casting System Casting Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Fielding, Randall Sidney [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    Casting optimization in the GACS included three broad areas; casting of U-10Zr pins, incorporation of an integral FCCI barrier, and development of a permanent crucible coating. U-10Zr casting was improved over last year’s results by modifying the crucible design to minimize contact with the colder mold. Through these modifications casting of a three pin batch was successful. Incorporation of an integral FCCI barrier also was optimized through furnace chamber pressure changes during the casting cycle to reduce gas pressures in the mold cavities which led to three full length pins being cast which incorporated FCCI barriers of three different thicknesses. Permanent crucible coatings were tested against a base case; 1500°C for 10 minutes in a U-20Pu-10Zr molten alloy. None of the candidate coating materials showed evidence of failure upon initial visual examination. In all areas of work a large amount of characterization will be needed to fully determine the effects of the optimization activities. The characterization activities and future work will occur next year.

  14. High integrity automotive castings

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, D. [Eck Industries Inc., St. Manitowoc, WI (United States)

    2007-07-01

    This paper described the High Integrity Magnesium Automotive Casting (HI-MAC) program, which was developed to ensure the widespread adoption of magnesium in structural castings. The program will encourage the use of low pressure permanent molds, squeeze casting, and electromagnetic pumping of magnesium into dies. The HI-MAC program is currently investigating new heat treatment methods, and is in the process of creating improved fluid flow and solidification modelling to produce high volume automotive components. In order to address key technology barriers, the program has been divided into 8 tasks: (1) squeeze casting process development; (2) low pressure casting technology; (3) thermal treatment; (4) microstructure control; (5) computer modelling and properties; (6) controlled molten metal transfer and filling; (7) emerging casting technologies; and (8) technology transfer throughout the automotive value chain. Technical challenges were outlined for each of the tasks. 1 ref., 3 tabs., 5 figs.

  15. Us and me : team identification and individual differentiation as complementary drivers of team members' citizenship and creative behaviors

    NARCIS (Netherlands)

    Janssen, O.; Huang, X

    2008-01-01

    The authors investigate team identification and individual differentiation as complementary drivers of team members' citizenship and creative behavior. As hypothesized, the results of a survey among 157 middle-management team members show team identification to be positively related to citizenship b

  16. Clinical Utility of Short Social Cognitive Tests in Early Differentiation of Behavioral Variant Frontotemporal Dementia from Alzheimer’s Disease

    DEFF Research Database (Denmark)

    Buhl, Christian; Stokholm, Jette; Gade, Anders

    2013-01-01

    Traditional cognitive tests used in clinical practice may not be sensitive enough for the early differentiation of behavioral variant frontotemporal dementia (bvFTD) from Alzheimer's disease (AD). A growing body of literature has shown that deficits in various aspects of social cognition can...

  17. Preterm Infants Who Are Prone to Distress: Differential Effects of Parenting on 36-Month Behavioral and Cognitive Outcomes

    Science.gov (United States)

    Poehlmann, Julie; Hane, Amanda; Burnson, Cynthia; Maleck, Sarah; Hamburger, Elizabeth; Shah, Prachi E.

    2012-01-01

    Background: The differential susceptibility (DS) model suggests that temperamentally prone-to-distress infants may exhibit adverse outcomes in negative environments but optimal outcomes in positive environments. This study explored temperament, parenting, and 36-month cognition and behavior in preterm infants using the DS model. We hypothesized…

  18. Evolution of halictine castes

    Science.gov (United States)

    Knerer, Gerd

    1980-03-01

    Social halictine bees have female castes that range from species with no size differences to those with a discrete bimodality. Female caste differences are inversely correlated with the number of males produced in the first brood. It is proposed that the sexual dimorphism of solitary forms is being usurped by the female caste system of species in the process of turning social. Thus, caste differences and summer male suppression are greatest in the social species originating from solitary precursors with distinct sexual dimorphism, and are least in species evolving from solitary ancestors with a continuous sexual polymorphism.

  19. Caste in Itself, Caste and Class, or Caste in Class

    OpenAIRE

    Ramkrishna Mukherjee

    2015-01-01

    After the British conquered Bengal and eventually the whole of India,they set out to administer the colony. In this context they encountered two phenomena with which they were not familiar: (1) the relation of people to land for production (and not for revenue receiving, household living, etc.), and (2) the caste system of India, viz. the jati strati?cation of society.

  20. Behavior and effect of Ti{sub 2}Ni phase during processing of NiTi shape memory alloy wire from cast ingot

    Energy Technology Data Exchange (ETDEWEB)

    Bhagyaraj, J. [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208 016 (India); Ramaiah, K.V.; Saikrishna, C.N.; Bhaumik, S.K. [Council of Scientific and Industrial Research, Materials Science Division, CSIR – National Aerospace Laboratories, Bangalore 560 017 (India); Gouthama, E-mail: gouthama@iitk.ac.in [Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur 208 016 (India)

    2013-12-25

    Highlights: •Ti{sub 2}Ni second phase particles forms in different sizes and shapes in cast ingot. •TEM evidences showed shearing/fragmentation of Ti{sub 2}Ni during processing. •Matrix close to Ti{sub 2}Ni experienced severe plastic deformation lead to amorphisation. •Ti{sub 2}Ni interfaces were mostly faceted and assist in nucleation of martensite. •Heterogeneity of microstructure observed near to and away from Ti{sub 2}Ni. -- Abstract: Binary NiTi alloy is one of the commercially successful shape memory alloys (SMAs). Generally, the NiTi alloy composition used for thermal actuator application is slightly Ti-rich. In the present study, vacuum arc melted alloy of 50.2Ti–Ni (at.%) composition was prepared and characterized using optical, scanning and transmission electron microcopy. Formation of second phase particles (SPPs) in the cast alloy and their influence on development of microstructure during processing of the alloy into wire form has been investigated. Results showed that the present alloy contained Ti{sub 2}Ni type SPPs in the matrix. In the cast alloy, the Ti{sub 2}Ni particles form in varying sizes (1–10 μm) and shapes. During subsequent thermo-mechanical processing, these SPPs get sheared/fragmented into smaller particles with low aspect ratio. The presence of SPPs plays a significant role in refinement of the microstructure during processing of the alloy. During deformation of the alloy, the matrix phase around the SPPs experiences conditions similar to that observed in severe plastic deformation of metallic materials, leading to localized amorphisation of the matrix phase.

  1. Differential Effectiveness of Interdependent and Dependent Group Contingencies in Reducing Disruptive Classroom Behavior

    Science.gov (United States)

    Hartman, Kelsey; Gresham, Frank

    2016-01-01

    Disruptive behavior in the classroom negatively affects all students' academic engagement, achievement, and behavior. Group contingencies have been proven effective in reducing disruptive behavior as part of behavior interventions in the classroom. The Good Behavior Game is a Tier 1 classwide intervention that utilizes an interdependent group…

  2. Comparative analysis of expressed sequence tags from three castes and two life stages of the termite Reticulitermes flavipes

    Directory of Open Access Journals (Sweden)

    Steller Matthew M

    2010-08-01

    Full Text Available Abstract Background Termites (Isoptera are eusocial insects whose colonies consist of morphologically and behaviorally specialized castes of sterile workers and soldiers, and reproductive alates. Previous studies on eusocial insects have indicated that caste differentiation and behavior are underlain by differential gene expression. Although much is known about gene expression in the honey bee, Apis mellifera, termites remain relatively understudied in this regard. Therefore, our objective was to assemble an expressed sequence tag (EST data base for the eastern subterranean termite, Reticulitermes flavipes, for future gene expression studies. Results Soldier, worker, and alate caste and two larval cDNA libraries were constructed, and approximately 15,000 randomly chosen clones were sequenced to compile an EST data base. Putative gene functions were assigned based on a BLASTX Swissprot search. Categorical in silico expression patterns for each library were compared using the R-statistic. A significant proportion of the ESTs of each caste and life stages had no significant similarity to those in existing data bases. All cDNA libraries, including those of non-reproductive worker and soldier castes, contained sequences with putative reproductive functions. Genes that showed a potential expression bias among castes included a putative antibacterial humoral response and translation elongation protein in soldiers and a chemosensory protein in alates. Conclusions We have expanded upon the available sequences for R. flavipes and utilized an in silico method to compare gene expression in different castes of an eusocial insect. The in silico analysis allowed us to identify several genes which may be differentially expressed and involved in caste differences. These include a gene overrepresented in the alate cDNA library with a predicted function of neurotransmitter secretion or cholesterol absorption and a gene predicted to be involved in protein

  3. Effect of thermomechanical treatments on the aging response of centrifugally cast silicon carbide/aluminum composites

    OpenAIRE

    May, Christopher William

    1992-01-01

    Approved for public release; distribution is unlimited Differential scanning calorimetry was conducted using centrifugally cast monolithic A3356 aluminum material and 26 volume present silicon carbide (SiC) particle reinforced A356 aluminum matrix composite material in as-cast, cast and rolled, and cast and extruded conditions. Electrical resistivity and matrix micro-hardness measurements during isothermal aging treatments were also conducted. The effects of thermo-mechanical processing ...

  4. Continuous cooling transformation behavior for heat treatment of spheroidal graphite cast iron. Kyujo kokuen chutetsu no netsushoriji ni okeru renzoku reikyaku hentai kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, T.; Matsumoto, H. (Shibaura Institute of Technology, Tokyo (Japan)); Kasugai, T. (National Research Institute for Metals, Tsukuba (Japan)); Koyama, M. (Automobile Foundry Co. Ltd., Yokohama (Japan))

    1992-08-25

    In order to study basic heat treatment properties of spheroidal graphite cast iron, the continuous cooling transformation(CCT) diagrams for the material equivallent to FCD700 under various austenitized conditions were obtained. There were 4 kinds of austenitized conditions varying from 1123K and 420s to 1323K and 1,800s. Eight kinds of cooling time from the austenitized temperature to 773K ranged from 6s to 4,000s. The transformation temperature was measured by a thermal expansion method. When the austenitized temperature was increased from 1123K to 1323K, ferrite and pearlite transformation regions moved a little in the CCT diagrams and the martensite transformation temperature decreased from 493K to 458K. The bainite region in the CCT diagrams disappeared at the austenite temperatures above 1223K. The nucleation sites of ferrite and pearlite in the spheroidal graphite cast iron were generated at grain boundary between austenite and graphite but not at grain boundary between austenites. The reason of such phenomena was also studied. 10 refs., 8 figs., 2 tabs.

  5. Model Test Research on the End Bearing Behavior of the Large-Diameter Cast-in-Place Concrete Pile for Jointed Rock Mass

    Directory of Open Access Journals (Sweden)

    Jingwei Cai

    2016-01-01

    Full Text Available For large-diameter, cast-in-place concrete piles, the end bearing capacity of a single pile is affected by discontinuous surfaces that exist in natural rock masses when the bearing layer of the pile end is located in the rock layer. In order to study the influence of the jointed dip angle on the bearing characteristics of the pile end, the discrete element models are adopted to simulate the mechanical characteristics of the jointed rock masses, and the model tests of the failure mode of the jointed rock masses were also designed. The results of the numerical calculations and modeling tests show that the joints, which have a filtering effect on the internal stress of the bedrock located at the pile end, change the load transferring paths. And the failure mode of the jointed rock foundation also changes as jointed dip angle changes. The rock located at the pile end generally presents a wedge failure mode. In addition, the Q-S curves obtained by model tests show that the ultimate end bearing capacity of a single pile is influenced by the jointed dip angle. The above results provide an important theoretical basis for how to correctly calculate end resistance for a cast-in-place concrete pile.

  6. Static and cyclic pullout behavior of cast-in-place headed and bonded anchors with large embedment depths in cracked concrete

    Energy Technology Data Exchange (ETDEWEB)

    Delhomme, F., E-mail: fabien.delhomme@insa-lyon.fr [University of Lyon, INSA-Lyon, LGCIE, F-69621 Villeurbanne (France); Roure, T.; Arrieta, B. [EDF SEPTEN Compagny, Civil Engineering, Villeurbanne (France); Limam, A. [University of Lyon, INSA-Lyon, LGCIE, F-69621 Villeurbanne (France)

    2015-06-15

    Highlights: • Optimizing the design and identifying margin of the headed fasteners used in French nuclear power plants. • Static and cyclic pullout tests on cast in place anchorage composed of an anchor plate welded to four headed or bonded rods. • Experimental data base on tests on anchor plates. • Anchor with large embedment depths in cracked concrete. • Edge effects. - Abstract: The equipment of French nuclear power plants is fixed on reinforced concrete structures with base plate with headed fasteners. EDF decided to carry out an experimental research program in partnership with LGCIE in order to optimize the design of the headed fasteners and identify margin. This article introduces the results of pullout tests on anchors with large embedment cast in place in a reinforced concrete block. The anchorage are composed of an anchor plate welded to four ribbed bars or headed smooth studs. The studied parameters are: the type of loading (static or cyclic), the edge distance, the state of cracking of the concrete block. The anchors with headed rods or ribbed bars have a steel rod failure mode in agreement with their initial design. However, an optimization of the size on the headed anchors seems to be expected in order to improve their installation. This experimental campaign will provide a data base enabling the development of numerical models in order to improve the design.

  7. A cast orientation index.

    Science.gov (United States)

    Ivanhoe, J R; Mahanna, G K

    1994-12-01

    This article describes a technique that allows multiple master casts to be precisely oriented to the same path of insertion and withdrawal. This technique is useful in situations where multiple fixed prosthodontic preparations require surveyed restorations and a single master cast is not available.

  8. Higher Education's Caste System

    Science.gov (United States)

    Iannone, Ron

    2004-01-01

    In this article, the author discusses the history of the present caste system in higher education. He shows how the public's perception of this caste system is based on image and not usually on the quality of teaching and curriculum in colleges and universities. Finally, he discusses a model for accessibility to higher education and how higher…

  9. Caste and power

    DEFF Research Database (Denmark)

    Roy, Dayabati

    2011-01-01

    This paper explores the institution of caste and its operation in a micro-level village setting of West Bengal, an Indian state, where state politics at grass roots level is vibrant with functioning local self-government and entrenched political parties. This ethnographic study reveals that caste...

  10. Multi-layers castings

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2010-01-01

    Full Text Available In paper is presented the possibility of making of multi-layers cast steel castings in result of connection of casting and welding coating technologies. First layer was composite surface layer on the basis of Fe-Cr-C alloy, which was put directly in founding process of cast carbon steel 200–450 with use of preparation of mould cavity method. Second layer were padding welds, which were put with use of TIG – Tungsten Inert Gas surfacing by welding technology with filler on Ni matrix, Ni and Co matrix with wolfram carbides WC and on the basis on Fe-Cr-C alloy, which has the same chemical composition with alloy, which was used for making of composite surface layer. Usability for industrial applications of surface layers of castings were estimated by criterion of hardness and abrasive wear resistance of type metal-mineral.

  11. Two insular regions are differentially involved in behavioral variant FTD and nonfluent/agrammatic variant PPA.

    Science.gov (United States)

    Mandelli, Maria Luisa; Vitali, Paolo; Santos, Miguel; Henry, Maya; Gola, Kelly; Rosenberg, Lynne; Dronkers, Nina; Miller, Bruce; Seeley, William W; Gorno-Tempini, Maria Luisa

    2016-01-01

    The non-fluent/agrammatic variant of primary progressive aphasia (nfvPPA) and the behavioral variant frontotemporal dementia (bvFTD) are focal neurodegenerative disorders belonging to the FTD-spectrum clinical syndromes. NfvPPA is characterized by effortful speech and/or agrammatism and left frontal atrophy, while bvFTD is characterized by social-emotional dysfunction often accompanied by right-lateralized frontal damage. Despite their contrasting clinical presentations, both disorders show prominent left anterior insula atrophy. We investigated differential patterns of insular sub-region atrophy in nfvPPA and bvFTD. Based on knowledge of insular connectivity and physiology, we hypothesized that the left superior precentral region of the dorsal anterior insula (SPGI) would be more atrophic in nvfPPA due to its critical role in motor speech, whereas the ventral anterior region would be more atrophied in bvFTD reflecting its known role in social-emotional-autonomic functions. Early stage nfvPPA and bvFTD patients matched for disease severity, age, gender and education and healthy controls participated in the study. Detailed clinical history, neurological examination, neuropsychological screening evaluation, and high-resolution T1-weighted brain magnetic resonance imaging (MRI) were collected. Voxel-based morphometry (VBM) was applied to perform group comparisons across the whole brain and in bilateral insula region of interest (ROI). Correlation analyses between insular sub-region atrophy and relevant clinical features were performed. Whole brain group comparisons between nfvPPA and bvFTD showed the expected predominantly left or right anterior insular atrophy pattern. ROI analysis of bilateral insula showed that the left SPGI was significantly more atrophied in nfvPPA compared to bvFTD, while the bilateral ventral anterior and right dorsal anterior insula sub-regions were more atrophied in bvFTD than nfvPPA. Only left SPGI volume correlated with speech production

  12. Microdefects in cast multicrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, E.; Klinger, D.; Bergmann, S. [Inst. of Crystal Growth Berlin (Germany)

    1995-08-01

    The microdefect etching behavior of cast multicrystalline BAYSIX and SILSO samples is mainly the same as that of EFG silicon, in spite of the very different growth parameters applied to these two techniques and the different carbon contents of the investigated materials. Intentional decorating of mc silicon with copper, iron and gold did not influence the results of etching and with help of infrared transmission microscopy no metal precipitates at the assumed microdefects could be established. There are many open questions concerning the origin of the assumed, not yet doubtless proved microdefects.

  13. The ancient Chinese casting techniques

    Directory of Open Access Journals (Sweden)

    Tan Derui

    2011-02-01

    Full Text Available In the course of Chinese civilization, which lasted more than 5,000 years, casting production has made a huge contribution. In this paper, some representative metal castings were presented. According to their forming techniques, they can be grouped into stone mould casting, clay mould casting, ablation casting, lost wax casting, stack casting, permanent mould casting, sand casting, etc. According to their materials, they can be categorized into tin bronze, bimetallic bronze, malleable cast iron, ductile cast iron, brass, cupronickel alloy (Packtong, etc. According to their surface decorative techniques they can be devided into gem inlay, gilding, gold and silver inlay, copper inlay, engraved decoration, surface tin-enrichment, mother-of-pearl inlay, burnished works with gold or silver inlay, surface coloring and cloisonné enamel, etc.

  14. Caste in Itself, Caste and Class, or Caste in Class

    Directory of Open Access Journals (Sweden)

    Ramkrishna Mukherjee

    2015-08-01

    Full Text Available After the British conquered Bengal and eventually the whole of India,they set out to administer the colony. In this context they encountered two phenomena with which they were not familiar: (1 the relation of people to land for production (and not for revenue receiving, household living, etc., and (2 the caste system of India, viz. the jati strati?cation of society.

  15. Study on Compressive Behavior of Open-cell Aluminum Foam by Gypsum Mould Infiltrating Casting%石膏型渗流法制备的开孔泡沫铝的压缩行为研究

    Institute of Scientific and Technical Information of China (English)

    吴进; 程和法; 黄笑梅; 张燕瑰; 胡志君

    2011-01-01

    本文采用可溶石膏型预制块,通过加压渗流的方法制备了泡沫纯铝、泡沫ZL101合金和泡沫ZL102合金,并通过准静态压缩实验研究了3种不同基体材料的泡沫铝的压缩行为及吸能性能.结果表明:通过石膏型渗流法制备的开孔泡沫铝合金的孔隙率可以达到85%~93.5%;泡沫铝基体材料的力学性能对泡沫铝压缩力学性能有重要影响;泡沫ZL101合金能够吸收最多的能量,且在较大的应力、应变范围内对材料起到缓冲保护作用.%The polymeric reticular sponge was choosen as the mother plate to make the soluble gypsum mould,and after that, through infiltrating casting to fabricate three kinds of open-cell aluminum foam, which are pure aluminum foam, ZL101 aluminum alloy foam and ZL102 aluminum alloy foam. The compressive behaviors and energy-absorption capacities of those different kinds of foams were investigated by the quasi-static compression test. The experimental results indicate that the porosity of the aluminum foams made by the gypsum mould infiltrating casting are 85%~93. 5%;The matrix properties have notable effects on the mechanical behaviors of foams;The ZL101 aluminum alloy foam can absorb the most energy and also can protect the materials in the larger ranges of stress and strain.

  16. An Investigation of the Effects of Differential Reinforcement of Alternative Behavior on Students with Mild/Moderate Disabilities in a School Classroom

    OpenAIRE

    Spangenberg, Katrina

    2008-01-01

    This study investigated the effects of differential reinforcement of alternative behavior (DRA), a behavior reduction procedure, on problem behavior exhibited by three elementary school students in a general education classroom. DRA involves reinforcement of an alternative behavior while withholding reinforcement for the inappropriate behavior. The three participants were classified as experiencing mild/moderate disabilities but received most services (and participated in this research) in a ...

  17. Clean Metal Casting

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

  18. Modelling of Filling, Microstructure Formation, Local Mechanical Properties and Stress – Strain Development in High-Pressure Die Cast Aluminium Castings

    DEFF Research Database (Denmark)

    Kotas, Petr; Hattel, Jesper Henri; Thorborg, Jesper

    2009-01-01

    inherently affects the component’s properties depending on design, metallurgy and casting technique. The wall thickness influences the coarseness of the microstructure and the material will have properties depending on the local metallurgical and thermal histories. This is independent on the material, i.......e. whether the casting is based on cast iron- or aluminium-alloys. The distribution of local properties in a casting might vary substantially which makes it complex to optimize the casting with good accuracy. Often, mechanical simulations of the load situation are based on the assumption that the cast...... product has constant material properties throughout the entire casting. Thus, if the microstructure is determined or predicted at a given point, it gives the possibility to calculate the local material behavior more realistically. In the present work, a test case of a complex high-pressure die cast part...

  19. Evolution of Social Insect Polyphenism Facilitated by the Sex Differentiation Cascade.

    Science.gov (United States)

    Klein, Antonia; Schultner, Eva; Lowak, Helena; Schrader, Lukas; Heinze, Jürgen; Holman, Luke; Oettler, Jan

    2016-03-01

    The major transition to eusociality required the evolution of a switch to canalize development into either a reproductive or a helper, the nature of which is currently unknown. Following predictions from the 'theory of facilitated variation', we identify sex differentiation pathways as promising candidates because of their pre-adaptation to regulating development of complex phenotypes. We show that conserved core genes, including the juvenile hormone-sensitive master sex differentiation gene doublesex (dsx) and a krüppel homolog 2 (kr-h2) with putative regulatory function, exhibit both sex and morph-specific expression across life stages in the ant Cardiocondyla obscurior. We hypothesize that genes in the sex differentiation cascade evolved perception of alternative input signals for caste differentiation (i.e. environmental or genetic cues), and that their inherent switch-like and epistatic behavior facilitated signal transfer to downstream targets, thus allowing them to control differential development into morphological castes.

  20. Evolution of Social Insect Polyphenism Facilitated by the Sex Differentiation Cascade

    Science.gov (United States)

    Klein, Antonia; Schultner, Eva; Lowak, Helena; Schrader, Lukas; Heinze, Jürgen; Holman, Luke; Oettler, Jan

    2016-01-01

    The major transition to eusociality required the evolution of a switch to canalize development into either a reproductive or a helper, the nature of which is currently unknown. Following predictions from the ‘theory of facilitated variation’, we identify sex differentiation pathways as promising candidates because of their pre-adaptation to regulating development of complex phenotypes. We show that conserved core genes, including the juvenile hormone-sensitive master sex differentiation gene doublesex (dsx) and a krüppel homolog 2 (kr-h2) with putative regulatory function, exhibit both sex and morph-specific expression across life stages in the ant Cardiocondyla obscurior. We hypothesize that genes in the sex differentiation cascade evolved perception of alternative input signals for caste differentiation (i.e. environmental or genetic cues), and that their inherent switch-like and epistatic behavior facilitated signal transfer to downstream targets, thus allowing them to control differential development into morphological castes. PMID:27031240

  1. Evolution of Social Insect Polyphenism Facilitated by the Sex Differentiation Cascade.

    Directory of Open Access Journals (Sweden)

    Antonia Klein

    2016-03-01

    Full Text Available The major transition to eusociality required the evolution of a switch to canalize development into either a reproductive or a helper, the nature of which is currently unknown. Following predictions from the 'theory of facilitated variation', we identify sex differentiation pathways as promising candidates because of their pre-adaptation to regulating development of complex phenotypes. We show that conserved core genes, including the juvenile hormone-sensitive master sex differentiation gene doublesex (dsx and a krüppel homolog 2 (kr-h2 with putative regulatory function, exhibit both sex and morph-specific expression across life stages in the ant Cardiocondyla obscurior. We hypothesize that genes in the sex differentiation cascade evolved perception of alternative input signals for caste differentiation (i.e. environmental or genetic cues, and that their inherent switch-like and epistatic behavior facilitated signal transfer to downstream targets, thus allowing them to control differential development into morphological castes.

  2. Symptomatic stent cast.

    LENUS (Irish Health Repository)

    Keohane, John

    2012-02-03

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  3. Symptomatic stent cast.

    Science.gov (United States)

    Keohane, John; Moore, Michael; O'Mahony, Seamus; Crosbie, Orla

    2008-02-01

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  4. CENTRIFUGAL CASTING MACHINE

    Science.gov (United States)

    Shuck, A.B.

    1958-04-01

    A device is described that is specifically designed to cast uraniumn fuel rods in a vacuunn, in order to obtain flawless, nonoxidized castings which subsequently require a maximum of machining or wastage of the expensive processed material. A chamber surrounded with heating elements is connected to the molds, and the entire apparatus is housed in an airtight container. A charge of uranium is placed in the chamber, heated, then is allowed to flow into the molds While being rotated. Water circulating through passages in the molds chills the casting to form a fine grained fuel rod in nearly finished form.

  5. Bainite obtaining in cast iron with carbides castings

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2010-01-01

    Full Text Available In these paper the possibility of upper and lower bainite obtaining in cast iron with carbides castings are presented. Conditions, when in cast iron with carbides castings during continuous free air cooling austenite transformation to upper bainite or its mixture with lower bainte proceeds, have been given. A mechanism of this transformation has been given, Si, Ni, Mn and Mo distribution in the eutectic cell has been tested and hardness of tested castings has been determined.

  6. The infralimbic and prelimbic medial prefrontal cortices have differential functions in the expression of anxiety-like behaviors in mice.

    Science.gov (United States)

    Suzuki, Satoshi; Saitoh, Akiyoshi; Ohashi, Masanori; Yamada, Misa; Oka, Jun-Ichiro; Yamada, Mitsuhiko

    2016-05-01

    The medial prefrontal cortex is a heterogeneous cortical structure composed of several nuclei, including the prelimbic (PL) and infralimbic (IL) cortices. We previously demonstrated in mice that PL activation with the sodium channel activator veratrine induces anxiety-like behaviors. However, the role of IL in the regulation of anxiety-like behaviors remained unclear. Therefore, in the present study, we investigated the role of the IL in the regulation of anxiety-like behaviors using pharmacological activation model with veratrine, and compared it with the role of the PL. Extracellular glutamate levels were measured by in vivo microdialysis-HPLC with an electrochemical detector, and behaviors were assessed using the open field test. In this study, extracellular glutamate levels rose significantly after perfusion of veratrine in the IL and PL. Interestingly, the PL activation produced anxiety-like behaviors, whereas the activation of the IL produced no anxiety-like behavior in mice. Although the IL is adjacent to the PL, these two regions of the brain have differential functions in the expression of anxiety-like behaviors.

  7. Stress responsiveness and anxiety-like behavior: The early social environment differentially shapes stability over time in a small rodent.

    Science.gov (United States)

    Sangenstedt, Susanne; Jaljuli, Iman; Sachser, Norbert; Kaiser, Sylvia

    2017-03-13

    The early social environment can profoundly affect behavioral and physiological phenotypes. We investigated how male wild cavy offspring, whose mothers had either lived in a stable (SE) or an unstable social environment (UE) during pregnancy and lactation, differed in their anxiety-like behavior and stress responsiveness. At two different time points in life, we tested the offspring's anxiety-like behavior in a dark-light test and their endocrine reaction to challenge in a cortisol reactivity test. Furthermore, we analyzed whether individual traits remained stable over time. There was no effect of the early social environment on anxiety-like behavior and stress responsiveness. However, at an individual level, anxiety-like behavior was stable over time in UE- but not in SE-sons. Stress responsiveness, in turn, was rather inconsistent in UE-sons and temporally stable in SE-sons. Conclusively, we showed for the first time that the early social environment differentially shapes the stability of behavioral and endocrine traits. At first glance, these results may be surprising, but they can be explained by the different functions anxiety-like behavior and stress responsiveness have.

  8. Combining noncontingent reinforcement and differential reinforcement schedules as treatment for aberrant behavior.

    OpenAIRE

    Marcus, B A; Vollmer, T R

    1996-01-01

    Research has shown that noncontingent reinforcement (NCR) can be an effective behavior-reduction procedure when based on a functional analysis. The effects of NCR may be a result of elimination of the contingency between aberrant behavior and reinforcing consequences (extinction) or frequent and free access to reinforcers that may reduce the participant's motivation to engage in aberrant behaviors or mands. If motivation is momentarily reduced, behavior such as mands may not be sensitive to p...

  9. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    White Cast Iron (Ⅰ) White cast iron or ‘white iron' refers to the type of cast iron in which all of the carbon exists as carbide;there is no graphite in the as-cast structure and the fractured surface shows a white colour.White cast iron can be divided in three classes:· Normal white cast iron — this iron contains only C,Si,Mn,P and S,with no other alloying elements.· Low-alloy white cast iron — the total mass fraction of alloying elements is less than 5%.

  10. Differential Parenting and Children's Behavioral Problems: Curvilinear Associations and Mother-Father Combined Effects

    Science.gov (United States)

    Meunier, Jean Christophe; Bisceglia, Rossana; Jenkins, Jennifer M.

    2012-01-01

    In this study the associations between mothers' and fathers' differential parenting and children's oppositional and emotional problems were examined. A curvilinear relationship between differential parenting and children's outcomes was hypothesized, as well as the combined effect of mothers' and fathers' parenting. Data came from a community…

  11. Rheology of composite solid propellants during motor casting

    Science.gov (United States)

    Rogers, C. J.; Smith, P. L.; Klager, K.

    1978-01-01

    In a study conducted to evaluate flow parameters of uncured solid composite propellants during motor casting, two motors (1.8M-lb grain wt) were cast with a PBAN propellant exhibiting good flow characteristics in a 260-in. dia solid rocket motor. Attention is given to the effects of propellant compositional and processing variables on apparent viscosity as they pertain to rheological behavior and grain defect formation during casting. It is noted that optimized flow behavior is impaired with solid propellant loading. Non-Newtonian pseudoplastic flow is observed, which is dependent upon applied shear stress and the age of the uncured propellant.

  12. Comprehensive study of the abrasive wear and slurry erosion behavior of an expanded system of high chromium cast iron and microstructural modification for enhanced wear resistance

    Science.gov (United States)

    Chung, Reinaldo Javier

    High chromium cast irons (HCCIs) have been demonstrated to be an effective material for a wide range of applications in aggressive environments, where resistances to abrasion, erosion and erosion-corrosion are required. For instance, machinery and facilities used in mining and extraction in Alberta's oil sands suffer from erosion and erosion-corrosion caused by silica-containing slurries, which create challenges for the reliability and maintenance of slurry pumping systems as well as other processing and handling equipment. Considerable efforts have been made to determine and understand the relationship between microstructural features of the HCCIs and their wear performance, in order to guide the material selection and development for specific service conditions with optimal performance. The focus was previously put on a narrow group of compositions dictated by ASTM A532. However, with recent advances in casting technology, the HCCI compositional range can be significantly expanded, which potentially brings new alloys that can be superior to those which are currently employed. This work consists of three main aspects of study. The first one is the investigation of an expanded system of white irons with their composition ranging from 1 to 6 wt.% C and 5 to 45 wt.% Cr, covering 53 alloys. This work has generated wear and corrosion maps and established correlation between the performance and microstructural features for the alloys. The work was conducted in collaboration with the Materials Development Center of Weir Minerals in Australia, and the results have been collected in a database that is used by the company to guide materials selection for slurry pump components in Alberta oil sands and in other mining operations throughout the world. The second part consists of three case studies on effects of high chromium and high carbon, respectively, on the performance of the HCCIs. The third aspect is the development of an approach to enhance the wear resistance of

  13. AI-Si-Cu-Mg(-Er)铸造铝合金的低周疲劳行为%Low-Cycle Fatigue Behavior of Cast AI-Si-Cu-Mg(-Er) Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    车欣; 徐志军; 陈立佳; 徐海健; 李锋

    2011-01-01

    对金属型铸造Al-Si-Cu-Mg和Al-Si-Cu-Mg-Er铝合金进行了疲劳试验,并研究了其室温下的低周疲劳行为.试验结果表明:金属型铸造Al-Si-Cu-Mg和Al-Si-Cu-Mg-Er铝合金表现为循环应变硬化和循环稳定,主要取决于外加总应变的高低;稀土元素Er的加入可提高金属型铸造Al-Si-Cu-Mg合金的循环变形抗力和疲劳寿命;金属型铸造Al-Si-Cu-Mg合金的塑性应变、弹性应变与断裂时的载荷反向次数之间呈直线关系,Al-Si-Cu-Mg-Er合金的弹性应变与疲劳断裂时的载荷反向次数之间也呈直线关系,但其塑性应变与疲劳断裂时的载荷反向次数之间则呈双线性关系.%Through the strain-controlled fatigue experiments, the low-cycle fatigue behavior of permanent-mold cast Al-Si-Cu-Mg and Al-Si-Cu-Mg-Er alloys at room temperature was investigated.The experimental results show that the Al-Si-Cu-Mg and Al-Si-Cu-Mg-Er alloys exhibit the cyclic strain hardening and cyclic stability, mainly depending on the imposed total strain amplitude. For the permanent-mold cast Al-Si-Cu-Mg alloy, the addition of Er can effectively enhance both cyclic deformation resistance and fatigue life of the alloys. A single-slope linear relation between plastic strain amplitude, elastic strain amplitude and reversals to failure is observed for permanent-mold cast Al-Si-Cu-Mg alloy. However, a two-slope linear relation between plastic strain amplitude and reversals to failure is noted for the Al-Si-Cu-Mg-Er alloy, although the corresponding relation between elastic strain amplitude and reversals to failure is linear.

  14. Microstructure and mechanical behavior of stir-cast Zn–27Al based composites reinforced with rice husk ash, silicon carbide, and graphite

    Directory of Open Access Journals (Sweden)

    Kenneth Kanayo Alaneme

    2017-04-01

    Full Text Available The microstructure and mechanical properties of Zn–27Al based composites reinforced with rice husk ash (RHA, silicon carbide (SiC, and graphite (Cg particles have been investigated. The Zn–27Al composites consisting of varied weight ratios of the reinforcing materials were produced using the stir casting process. Hardness test, tensile properties evaluation, fracture toughness determination, and microstructural examination, were used to characterize the composites produced. Results show that the microstructures of the composites are similar, consisting of the dendritic structure of the Zn–27Al alloy matrix with fine dispersion of the reinforcing particles. The hardness of the composites decreased with increase in the weight percent of RHA (and corresponding decrease in SiC weight percent in the reinforcement. The tensile strength and yield strength decreased slightly with increase in the weight ratio of RHA in the composites with a maximum of 8.5% and 9.6% reductions respectively observed for as much as 40% RHA (corresponding to 40% reduction in SiC in the hybrid reinforcement. Although some of the composite compositions containing RHA had slightly higher % elongation values compared with those without RHA, it was generally observed that the % elongation was invariant to the composite RHA content. The fracture toughness of the composites increases with increase in the weight percent of RHA with as much as a 20% increase obtained for as much as 40% RHA (corresponding to 40% reduction in SiC in the hybrid reinforcement.

  15. Behavior of Zr-Rich Phase in a Cast NiAl-33.5Cr-0.5ZrAlloy during Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    There are many Zr particles in as-cast NiAl-33.5Cr-0.5Zr (at. pct) alloy, which usually exist at the edge of eutectic ofβ-NiAl and α-Cr. After air and furnace cooling solution treatments,for 1400℃, 2 h and 1450℃, 1 h, pure Zr phase remains in the furnace cooling (F.C.) state alloys and Ni2AlZr phase forms in the air cooling (A.C.) state alloys. During solution treatment at 1450℃, bulk and "fish bone" shape Zr-rich phases form respectively in F.C. and A.C. state alloys. A 'river' shape Ni2AlZr phase forms after 1450℃ for 1h F.C. and 850℃ for 12 h, F.C..The alloy has less pure Zr and Ni2AlZr phase after 1400℃ with both air and furnace cooling followed by 850℃ and 950℃ for 112 h, F.C. aging treatments, respectively. Additionally, there is a ternary eutectic of NiAlZr and a phase enriched Zr and Cr forms at the edge of the eutectic ofβ-NiAl and c-Cr in the alloy treated at 1400℃, 2 h, F.C. and 950℃, 12 h, F.C.

  16. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17 Percent Cr and Cu-17 Percent Cr-5 Percent Al Part II: Scale Microstructures

    Science.gov (United States)

    Raj, Sai V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. Details of the oxidation kinetics of these alloys were discussed in Part I. This paper analyzes the microstructures of the scale and its composition in an attempt to elucidate the oxidation mechanisms in these alloys. The scales formed on Cu-17%Cr specimens oxidized between 773 and 973 K consisted of external CuO and subsurface Cu2O layers. The total thickness of these scales varied from about 10 m at 773 K to about 450 m at 973 K. In contrast, thin scales formed on Cu-17%Cr-5%Al alloys oxidized between 773 and 1173 K. The exact nature of these scales could not be determined by x-ray diffraction but energy dispersive spectroscopy analyses were used to construct a scale composition map. Phenomenological oxidation mechanisms are proposed for the two alloys.

  17. Comparison of the Isothermal Oxidation Behavior of As-Cast Cu-17 Percent Cr and Cu-17 Percent Cr-5 Percent Al. Part 2; Scale Microstructures

    Science.gov (United States)

    Raj, S. V.

    2008-01-01

    The isothermal oxidation kinetics of as-cast Cu-17%Cr and Cu-17%Cr-5%Al in air were studied between 773 and 1173 K under atmospheric pressure. Details of the oxidation kinetics of these alloys were discussed in Part I. This paper analyzes the microstructures of the scale and its composition in an attempt to elucidate the oxidation mechanisms in these alloys. The scales formed on Cu-17%Cr specimens oxidized between 773 and 973 K consisted of external CuO and subsurface Cu2O layers. The total thickness of these scales varied from about 10 m at 773 K to about 450 m at 973 K. In contrast, thin scales formed on Cu-17%Cr-5%Al alloys oxidized between 773 and 1173 K. The exact nature of these scales could not be determined by x-ray diffraction but energy dispersive spectroscopy analyses were used to construct a scale composition map. Phenomenological oxidation mechanisms are proposed for the two alloys.

  18. Low-cycle Fatigue Behavior of Permanent-mold Cast Al-Si-Cu-Er Alloy%金属型铸造Al-Si-Cu-Er合金的低周疲劳行为

    Institute of Scientific and Technical Information of China (English)

    吴伟; 王爽; 吕伟; 车欣

    2011-01-01

    通过在不同外加总应变幅下进行应变控制的室温低周疲劳试验,探讨了金属型铸造A1-Si-Cu-Er合金的疲劳变形和断裂行为.结果表明,在低周疲劳加载下,金属型铸造Al-Si-Cu-Er合金表现为循环应变硬化、循环稳定;金属型铸造Al-Si-Cu-Er合金的弹性应变幅、塑性应变幅与疲劳断裂时的载荷反向周次之间的关系可分别用Basquin和Coffin-Manson公式描述;金属型铸造Al-Si-Cu-Er合金在低周疲劳加载条件下,裂纹均以穿晶方式萌生于试样表面,并以穿晶方式扩展.%The fatigue deformation and fracture behavior of permanent-mold cast Al-Si-Cu-Er alloy were investigated by low-cycle fatigue test at room temperature under different total strain amplitudes. The results show that permanent-mold cast Al-Si-Cu-Er alloy exhibits cyclic strain hardening and stable cyclic stress response during fatigue deformation, which mainly depend on the imposed total strain. The relation between elastic strain amplitude, plastic strain amplitude and reversals to failure can be described by Coffin-Manson and Basquin equations,respectiveiy. In addition, the fatigue cracks initiate at the free surface of fatigue specimens and propagate in a transgranular mode under low-cycle fatigue.

  19. Effects of casting speed on microstructure and segregation of electromagnetically stirred Aluminum alloy in continuous casting process

    Institute of Scientific and Technical Information of China (English)

    LEE Dock-Young; KANG Suk-Won; CHO Duck-Ho; KIM Ki-Bae

    2006-01-01

    Recently, a semi-solid metal processing has been acknowledged as a cost-effective technique to be able to manufacture high quality product for the transportation industry.In this study a hypo-eutectic Al alloy was fabricated by means of an electromagnetic stirrer in continuous casting process and the microstructural change during solidification due to a fluid flow by electromagnetic stirring was examined.Due to the forced fluid flow during solidification a dendritic phase of primary α phase of Al alloy was turned into a globular phase, which can make the Al alloy get a thixotropic behavior in the semi-solid region.In order to establish the quantitative relationship between microstructure and the process parameters, the morphology shape, a silicon distribution and a size of primary α phase were observed according to casting speed in continuous casting machine.The primary α phase was turned into the degenerate dendrites approaching a spherical configuration with increasing casting speed.The fine-grained and equiaxed microstructure appeared at higher casting speed.A segregation behavior of Si element was declined with increasing casting speed and a very uniform distribution of Si element was observed on the billet at a casting speed of 600 mm·min-1.A thickness of the solidifying shell of the billet was shortened with increasing the casting speed.

  20. Differential Efficacy of Home Monitoring and Cognitive-Behavioral Treatment for Decreasing Children's Maladaptive Nighttime Fears

    Science.gov (United States)

    Pincus, Donna B.; Weiner, Courtney L.; Friedman, Alice G.

    2012-01-01

    A number of studies have demonstrated the efficacy of brief cognitive-behavioral interventions for treating childhood nighttime fears. The purpose of the present study is to determine whether behavior changes could be initiated and maintained with home monitoring and reinforcement alone. Sixteen children, ages 6 to 11, with severe, disruptive…

  1. Reactive vs. Proactive Antisocial Behavior: Differential Correlates of Child ADHD Symptoms?

    Science.gov (United States)

    Bennett, David S.; Pitale, Maria; Vora, Vaishali; Rheingold, Alyssa A.

    2004-01-01

    This study examines the relation between proactive and reactive antisocial behavior with Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms. Caregivers of children aged 8 to 15 (n = 84) being evaluated at a child psychiatry outpatient clinic served as participants. Given the conceptual similarity between reactive antisocial behavior (ASB)…

  2. Treatment of Multiply Controlled Problem Behavior with Procedural Variations of Differential Reinforcement

    Science.gov (United States)

    Neidert, Pamela L.; Iwata, Brian A.; Dozier, Claudia L.

    2005-01-01

    We describe the assessment and treatment of 2 children with autism spectrum disorder whose problem behaviors (self-injury, aggression, and disruption) were multiply controlled. Results of functional analyses indicated that the children's problem behaviors were maintained by both positive reinforcement (attention) and negative reinforcement (escape…

  3. Differential Effects of Seating Arrangements on Disruptive Behavior of Fifth Grade Students during Independent Seatwork

    Science.gov (United States)

    Bicard, David F.; Ervin, Angela; Bicard, Sara C.; Baylot-Casey, Laura

    2012-01-01

    We investigated teacher versus student seat selection in the context of group and individual seating arrangements. Disruptive behavior during group seating occurred at twice the rate when students chose their seats than when the teacher chose. During individual seating, disruptive behavior occurred more than three times as often when the students…

  4. Differential gene expression associated with honey bee grooming behavior in response to varroa mites

    Science.gov (United States)

    Honey bee (Apis mellifera) grooming behavior is an important mechanism of resistance against the parasitic mite Varroa destructor. This research was conducted to study associations between grooming behavior and the expression of selected immune, neural, detoxification, developmental and health-relat...

  5. Tyraminergic and Octopaminergic Modulation of Defensive Behavior in Termite Soldier.

    Directory of Open Access Journals (Sweden)

    Yuki Ishikawa

    Full Text Available In termites, i.e. a major group of eusocial insects, the soldier caste exhibits specific morphological characteristics and extremely high aggression against predators. Although the genomic background is identical to the other non-aggressive castes, they acquire the soldier-specific behavioral character during the course of caste differentiation. The high aggressiveness and defensive behavior is essential for colony survival, but the neurophysiological bases are completely unknown. In the present study, using the damp-wood termite Hodotermopsis sjostedti, we focused on two biogenic amines, octopamine (OA and tyramine (TA, as candidate neuromodulators for the defensive behavior in soldiers. High-performance liquid chromatographic analysis revealed that TA levels in the brain and suboesophageal ganglion (SOG and the OA level in brain were increased in soldiers than in pseudergates (worker caste. Immunohistochemical analysis revealed that TA/OA neurons that innervate specific areas, including the mandibular muscles, antennal nerve, central complex, suboesophageal ganglion, and thoracic and/or abdominal ganglia, were enlarged in a soldier-specific manner. Together with the results that pharmacological application of TA promoted the defensive behavior in pseudergates, these findings suggest that the increased TA/OA levels induce the higher aggressiveness and defensive behavior in termite soldiers. The projection targets of these soldier-specific enlarged TA/OA neurons may have important roles in the higher aggressiveness and defensive behavior of the termite soldiers, inducing the neuronal transition that accompanies external morphological changes.

  6. Inference of optimal speed for sound centrifugal casting of Al-12Si alloys

    Science.gov (United States)

    Agari, Shailesh Rao; Mukunda, P. G.; Rao, Shrikantha S.; Sudhakar, K. G.

    2011-05-01

    True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.

  7. Anabolic androgenic steroids differentially affect social behaviors in adolescent and adult male Syrian hamsters.

    Science.gov (United States)

    Salas-Ramirez, Kaliris Y; Montalto, Pamela R; Sisk, Cheryl L

    2008-02-01

    Anabolic androgenic steroids (AAS) are synthetic derivatives of testosterone used by over half a million adolescents in the United States for their tissue-building potency and performance-enhancing effects. AAS also affect behavior, including reports of heightened aggression and changes in sexual libido. The expression of sexual and aggressive behaviors is a function of complex interactions among hormones, social context, and the brain, which is extensively remodeled during adolescence. Thus, AAS may have different consequences on behavior during adolescence and adulthood. Using a rodent model, these studies directly compared the effects of AAS on the expression of male sexual and aggressive behaviors in adolescents and adults. Male Syrian hamsters were injected daily for 14 days with either vehicle or an AAS cocktail containing testosterone cypionate (2 mg/kg), nandrolone decanoate (2 mg/kg), and boldenone undecylenate (1 mg/kg), either during adolescence (27-41 days of age) or in adulthood (63-77 days of age). The day after the last injection, males were tested for either sexual behavior with a receptive female or agonistic behavior with a male intruder. Adolescent males treated with AAS showed significant increases in sexual and aggressive behaviors relative to vehicle-treated adolescents. In contrast, AAS-treated adults showed significantly lower levels of sexual behavior compared with vehicle-treated adults and did not show heightened aggression. Thus, adolescents, but not adults, displayed significantly higher behavioral responses to AAS, suggesting that the still-developing adolescent brain is more vulnerable than the adult brain to the adverse consequences of AAS on the nervous system and behavior.

  8. Worker caste determination in the army ant Eciton burchellii.

    Science.gov (United States)

    Jaffé, Rodolfo; Kronauer, Daniel J C; Kraus, F Bernhard; Boomsma, Jacobus J; Moritz, Robin F A

    2007-10-22

    Elaborate division of labour has contributed significantly to the ecological success of social insects. Division of labour is achieved either by behavioural task specialization or by morphological specialization of colony members. In physical caste systems, the diet and rearing environment of developing larvae is known to determine the phenotype of adult individuals, but recent studies have shown that genetic components also contribute to the determination of worker caste. One of the most extreme cases of worker caste differentiation occurs in the army ant genus Eciton, where queens mate with many males and colonies are therefore composed of numerous full-sister subfamilies. This high intracolonial genetic diversity, in combination with the extreme caste polymorphism, provides an excellent test system for studying the extent to which caste determination is genetically controlled. Here we show that genetic effects contribute significantly to worker caste fate in Eciton burchellii. We conclude that the combination of polyandry and genetic variation for caste determination may have facilitated the evolution of worker caste diversity in some lineages of social insects.

  9. Mechanical behavior analysis and calculation model discussion of large span cast-in-situ floors%大跨度现浇楼盖力学性能分析及计算模型研究

    Institute of Scientific and Technical Information of China (English)

    周学军; 张慧武; 傅挺萌; 崔璐

    2015-01-01

    研究大跨度现浇楼盖的力学性能和计算模型可以更好的使其运用于工程实践。文章借助ANSYS有限元分析软件,分别对大跨度蜂巢芯砼空腹楼盖、砼叠合箱网梁楼盖和组合塑料模盒砼空心楼盖进行静力学分析,得到其挠度和应力云图;对某27 m大跨度现浇楼盖进行三维实体建模,研究其在竖向均布荷载下的受力性能,通过分析挠度和应力云图,探讨了大跨度现浇楼盖的计算模型。结果表明:三种楼盖的变形与实心板是一致的,肋间板条与肋梁的变形也基本上一致,三种楼盖的受力性能均类似于实心板,是一种“带肋的板”;27 m大跨度现浇楼盖的最大拉应力出现在楼盖板底中心处,楼盖应力分布均匀,其计算模型可以简化成实心板,整体结构可按板柱结构考虑。%Mechanical behavior and calculation model of the large-span Cast-in-situ floor were studied, which can make it better used in engineering practice. Aiming at the large span Honeycombed-core hollow floor,the concrete composite cage beam floor and the combined plastic mold boxes concrete hollow floor,static analysis was analyzed by using ANSYS finite element analysis software,which obtains their deflection and stress nephograms. A three-dimensional solid model of a 27 m large-span Cast-in-situ floor was established to study its mechanical behavior under the vertical uniformly distributed load,and its calculation model was studied by analyzing its deflection and stress nephograms. The results show:deformation of three kinds of floor are consistent with the solid plate, deformation of the floor in the middle of rib beams is consistent with rib beams,and their mechanical behavior are all similar to solid plate,which means they are actually“plates with ribs”;the first main stress of the 27m large-span Cast-in-situ floor appears in the bottom center of the floor,the stress of floor is homogeneous

  10. Structure and properties of stir-cast zinc alloys

    Energy Technology Data Exchange (ETDEWEB)

    LeHuy, H.; Blain J.; Masounave, J.; Bata, G.L. (Industrial Materials Research Institute, Boucherville, P.Q. (Canada))

    Stir casting (or rheocasting) of ZA-27 zinc alloys was investigated experimentally. By vigorously agitating the alloys during cooling, the dendrites that were forming were fragmented giving a unique structure composed of spherical and rosette shaped particles suspended in the remaining liquid. Under high shear rates ({center dot}{gamma} = 300s{sup {minus}1} or more) the slurries with primary particle concentrations as high as 60% displayed viscosities as low as 20 poises and could easily be casted. The effects of processing variables such as shearing and cooling rates and casting temperatures were studied. Their relative importance on the rheological and microstructural behavior of the stir cast alloys are discussed. Results from viscosity measurements on slurries show that non-dendritical ZA-27 alloys obey a power law fluid model. Finally, results from mechanical and compressive studies carried out on solidified slurries are discussed and compared to conventional casted and wrought alloy properties.

  11. The differential effects of Autism and Down's syndrome on sexual behavior.

    Science.gov (United States)

    Ginevra, Maria Cristina; Nota, Laura; Stokes, Mark A

    2016-01-01

    Although sexuality plays a major role in the socialization of people, few studies have examined the sexual behaviors of individuals with developmental disabilities. Because of this, we decided to investigate sexuality in adolescents with autism spectrum disorder (ASD) and Down's syndrome (Ds) and to compare them with typically developing adolescents, by surveying their parents. Specifically, it was hypothesized that young people with ASD would display lower levels over five domains: social behavior, privacy, sex education, sexual behavior, and parental concerns, than peers with Ds and typically developing young people. In addition, we sought to verify developmental trends in five domains with age for each group. Overall, 269 parents participated; 94 parents of typically developing adolescents, 93 parents of adolescents diagnosed with Ds, and 82 parents of adolescents diagnosed with ASD. Participants were surveyed with a Sexual Behavior Scale developed by Stokes and Kaur [] that assesses parents' reports of their child's: social behavior, privacy awareness, sex education, sexual behavior and parental concerns about the child's behaviors. It was found that three groups were significantly different on all five domains, adolescents with ASD reportedly displaying lower levels than other groups. Moreover, there was a significant improvement in knowledge of privacy and parental concerns with age for adolescents with ASD and a decline in sex education for adolescents with Ds. The results obtained emphasize the need to train adolescents with developmental disability, and especially for adolescents with ASD through sex education programs.

  12. Insights into glass transition and relaxation behavior using temperature-modulated differential scanning calorimetry

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, J.C.; Allan, D.C.;

    Temperature-modulated differential scanning calorimetry (TMDSC) is based on conventional DSC but with a sinusoidally modulated temperature path. Our simulations of TMDSC signals prove that the frequency correction of non-reversing heat flow can give a master curve within a certain range of freque......Temperature-modulated differential scanning calorimetry (TMDSC) is based on conventional DSC but with a sinusoidally modulated temperature path. Our simulations of TMDSC signals prove that the frequency correction of non-reversing heat flow can give a master curve within a certain range...

  13. Socioeconomic factors differentiating maternal and child health-seeking behavior in rural Bangladesh: A cross-sectional analysis

    Directory of Open Access Journals (Sweden)

    Becker Stan

    2010-04-01

    Full Text Available Abstract Background There has been an increasing availability and accessibility of modern health services in rural Bangladesh over the past decades. However, previous studies on the socioeconomic differentials in the utilization of these services were based on a limited number of factors, focusing either on preventive or on curative modern health services. These studies failed to collect data from remote rural areas of the different regions to examine the socioeconomic differentials in health-seeking behavior. Methods Data from 3,498 randomly selected currently married women from three strata of households within 128 purposively chosen remote villages in three divisions of Bangladesh were collected in 2006. This study used bivariate and multivariate logistic analyses to examine both curative and preventive health-seeking behaviors in seven areas of maternal and child health care: antenatal care, postnatal care, child delivery care, mother's receipt of Vitamin A postpartum, newborn baby care, care during recent child fever/cough episodes, and maternal coverageby tetanus toxoid (TT. Results A principal finding was that a household's relative poverty status, as reflected by wealth quintiles, was a major determinant in health-seeking behavior. Mothers in the highest wealth quintile were significantly more likely to use modern trained providers for antenatal care, birth attendance, post natal care and child health care than those in the poorest quintile (χ2, p Conclusion Within rural areas of Bangladesh, where overall poverty is greater and access to health care more difficult, wealth differentials in utilization remain pronounced. Those programs with high international visibility and dedicated funding (e.g., Immunization and Vitamin A delivery have higher overall prevalence and a more equitable distribution of beneficiaries than the use of modern trained providers for basic essential health care services. Implications of these findings and

  14. Behavioral Differentiation Induced by Insecticide Lambda-Cyhalothrin in Mosquito Fish, Gambusia affinis

    Directory of Open Access Journals (Sweden)

    Utku GÜNER

    2016-04-01

    Full Text Available Test toxic material, one of most used pesticide, the Lambda cyhalothrin (LCY (TEKVANDO 5EC belongs to a group of chemicals called synthetic pyrethroids and pesticides and potential toxic pollutant contaminating aquatic ecosystems, was investigated in the present study for behavioral toxicology. Mosquito fish, Gambusia affinis (Baird & Girard, 1853 were selected for responses of Lambda cyhalothrin by Using to video-based movement analysis system. Selected 3 different doses 0.1, 0.5 and 0.75 ppm were used analyzed behavioral changes according to control group. The following behaviors were measured: total distance, travelled and average speed for treatment and control groups, maximum and average speed and time moving away from the dose applied point. This suggests that LCY contamination has the potential to significantly affect (p<0.05 the behavior of Mosquito fish, G. affinis.

  15. An Early Manifestation of Differential Behavior toward Children of the Same and Opposite Sex.

    Science.gov (United States)

    Wasserman, Gail A.; Stern, Daniel N.

    1978-01-01

    Assessed individual (age, sex) and dyadic (same-sex, opposite-sex) differences in approach behaviors and investigated possible explanations for such differences. The subjects were 134 White preschool children, aged three to five. (MP)

  16. The Asymptotic Behavior for Second-Order Neutral Stochastic Partial Differential Equations with Infinite Delay

    Directory of Open Access Journals (Sweden)

    Huabin Chen

    2011-01-01

    Full Text Available By establishing two Lemmas, the exponential stability and the asymptotical stability for mild solution to the second-order neutral stochastic partial differential equations with infinite delay are obtained, respectively. Our results can generalize and improve some existing ones. Finally, an illustrative example is given to show the effectiveness of the obtained results.

  17. Cognitive and Affective Orientations and Teaching Behaviors--A Study of Differentiation.

    Science.gov (United States)

    Kremer, Lya

    1981-01-01

    Suggests that teachers can be differentiated by their cognitive or affective orientations, reflected in the objectives they select and in the stimuli and questions they present in the classroom. Proposes use of aptitude-treatment interactions in order to clarify the best methods to use for personalized teacher training. (JD)

  18. Multilevel Mediation: Cumulative Contextual Risk, Maternal Differential Treatment, and Children's Behavior within Families

    Science.gov (United States)

    Meunier, Jean Christophe; Boyle, Michael; O'Connor, Thomas G.; Jenkins, Jennifer M.

    2013-01-01

    This study tests the hypothesis that links between contextual risk and children's outcomes are partially explained by differential parenting. Using multi-informant measurement and including up to four children per family (M[subscript age] = 3.51, SD = 2.38) in a sample of 397 families, indirect effects (through maternal differential…

  19. On the asymptotic behavior of solutions of certain third-order nonlinear differential equations

    Directory of Open Access Journals (Sweden)

    Cemil Tunç

    2005-01-01

    Full Text Available We establish sufficient conditions under which all solutions of the third-order nonlinear differential equation x ⃛+ψ(x,x˙,x¨x¨+f(x,x˙=p(t,x,x˙,x¨ are bounded and converge to zero as t→∞.

  20. Experimental study of the differential effects of playing versus watching violent video games on children's aggressive behavior.

    Science.gov (United States)

    Polman, Hanneke; de Castro, Bram Orobio; van Aken, Marcel A G

    2008-01-01

    There is great concern about the effects of playing violent video games on aggressive behavior. The present experimental study was aimed at investigating the differential effects of actively playing vs. passively watching the same violent video game on subsequent aggressive behavior. Fifty-seven children aged 10-13 either played a violent video game (active violent condition), watched the same violent video game (passive violent condition), or played a non-violent video game (active non-violent condition). Aggression was measured through peer nominations of real-life aggressive incidents during a free play session at school. After the active participation of actually playing the violent video game, boys behaved more aggressively than did the boys in the passive game condition. For girls, game condition was not related to aggression. These findings indicate that, specifically for boys, playing a violent video game should lead to more aggression than watching television violence.

  1. Microstructures of electromagnetic casting and direct chill casting LY12 aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    曹志强; 金俊泽; 郝海; 贾非

    2003-01-01

    LY12 aluminum alloys made by electromagnetic casting (EMC) and direct chill casting (DCC), were analyzed by optical microscope, differential scanning calorimetry, transmission electron microscope and X-ray diffraction. It is found that the surface and subsurface quality of the ingot is improved largely due to the absence of an ingot mold, which is impossible to achieve with conventional DCC. It is also found that the intense forced convection can promote the fast superheat evacuation and break the dendrite arms, leading to the grain multiplication and the appearance of a fine equiaxed grains over the whole cross section. As a result, the hardness of EMC specimens increases one time than that from DCC in the as-cast state. Even though after the solid solution treatment and the artificial aging, the DCC ingot still can not get the same hardness as EMC ones.

  2. Casting Characteristics of Aluminum Die Casting Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  3. Characterization of Ni-Cr alloys using different casting techniques and molds.

    Science.gov (United States)

    Chen, Wen-Cheng; Teng, Fu-Yuan; Hung, Chun-Cheng

    2014-02-01

    This study differentiated the mechanical properties of nickel-chromium (Ni-Cr) alloys under various casting techniques (different casting molds and casting atmospheres). These techniques were sampled by a sand mold using a centrifugal machine in ambient air (group I) and electromagnetic induction in an automatic argon castimatic casting machine (group II). The specimen casting used a graphite mold by a castimatic casting machine (group III). The characteristics of the Ni-Cr alloys, yield and ultimate tensile strength, bending modulus, microhardness, diffraction phase, grindability, ability to spring back, as well as ground microstructure and pattern under different casting conditions were evaluated. The group III specimens exhibited the highest values in terms of strength, modulus, hardness, and grindability at a grind rate of 500 rpm. Moreover, group III alloys exhibited smaller grain sizes, higher ability to spring back, and greater ductility than those casted by sand investment (groups I and II). The main factor, "casting mold," significantly influenced all mechanical properties. The graphite mold casting of the Ni-Cr dental alloys in a controlled atmosphere argon casting system provided an excellent combination of high mechanical properties and good ability to spring back, and preserved the ductile properties for application in Ni-Cr porcelain-fused system. The results can offer recommendations to assist a prosthetic technician in selecting the appropriate casting techniques to obtain the desired alloy properties.

  4. Pax6-dependent cortical glutamatergic neuronal differentiation regulates autism-like behavior in prenatally valproic acid-exposed rat offspring.

    Science.gov (United States)

    Kim, Ki Chan; Lee, Dong-Keun; Go, Hyo Sang; Kim, Pitna; Choi, Chang Soon; Kim, Ji-Woon; Jeon, Se Jin; Song, Mi-Ryoung; Shin, Chan Young

    2014-02-01

    Imbalance in excitatory/inhibitory signal in the brain has been proposed as one of the main pathological features in autism spectrum disorders, although the underlying cellular and molecular mechanism is unclear yet. Because excitatory/inhibitory imbalance can be induced by aberration in glutamatergic/GABAergic neuronal differentiation, we investigated the mechanism of dysregulated neuronal differentiation between excitatory and inhibitory neurons in the embryonic and postnatal brain of prenatally valproic acid-exposed rat offspring, which is often used as an animal model of autism spectrum disorders. Transcription factor Pax6, implicated in glutamatergic neuronal differentiation, was transiently increased in embryonic cortex by valproate exposure, which resulted in the increased expression of glutamatergic proteins in postnatal brain of offspring. Chromatin immunoprecipitation showed increased acetylated histone binding on Pax6 promoter region, which may underlie the transcriptional up-regulation of Pax6. Other histone deacetylase (HDAC) inhibitors including TSA and SB but not valpromide, which is devoid of HDAC inhibitor activity, induced Pax6 up-regulation. Silencing Pax6 expression in cultured rat primary neural progenitor cells demonstrated that up-regulation of Pax6 plays an essential role in valproate-induced glutamatergic differentiation. Blocking glutamatergic transmission with MK-801 or memantine treatment, and to a lesser extent with MPEP treatment, reversed the impaired social behaviors and seizure susceptibility of prenatally valproate-exposed offspring. Together, environmental factors may contribute to the imbalance in excitatory/inhibitory neuronal activity in autistic brain by altering expression of transcription factors governing glutamatergic/GABAergic differentiation during fetal neural development, in conjunction with the genetic preload.

  5. Fired up or burned out? How developmental challenge differentially impacts leader behavior.

    Science.gov (United States)

    Courtright, Stephen H; Colbert, Amy E; Choi, Daejeong

    2014-07-01

    Leadership development research has largely drawn on experiential and enactive learning theories to explore the positive effects of developmental challenge on leaders. In contrast, we examined potential positive and negative effects of developmental challenge (i.e., challenging job assignments) on leader behavior through an alternative theoretical lens--transactional stress theory. We predicted, on one hand, that developmental challenge may be associated with higher leader engagement and transformational leadership behavior; however, developmental challenge also has the potential to be associated with higher leader emotional exhaustion and laissez-faire leadership behavior. We further proposed that leadership self-efficacy (LSE) moderates these potential effects of developmental challenge and helps explain why leaders react either positively or negatively to developmental challenge. We tested our hypotheses in a sample of 153 leaders and 631 direct reports at a Fortune 500 company. Findings supported positive relationships among developmental challenge, leader engagement, and transformational leadership. However, we also found support for significant relationships among developmental challenge, emotional exhaustion, and laissez-faire leadership. Additionally, leaders lower in LSE were more likely to encounter the negative effects of developmental challenge by experiencing increased emotional exhaustion and displaying laissez-faire leadership behaviors. Our study contributes to theory and practice by elucidating a "dark side" of developmental challenge, identifying LSE as a moderator of the negative effects of developmental challenge, identifying antecedents of transformational and laissez-faire leadership behaviors, and investigating demands and stress in leadership roles.

  6. Metatraits of the Big Five differentially predict engagement and restraint of behavior.

    Science.gov (United States)

    Hirsh, Jacob B; Deyoung, Colin G; Peterson, Jordan B

    2009-08-01

    Although initially believed to contain orthogonal dimensions, the Big Five personality taxonomy appears to have a replicable higher-order structure, with the metatrait of Plasticity reflecting the shared variance between Extraversion and Openness/Intellect, and the metatrait of Stability reflecting the shared variance among Neuroticism, Agreeableness, and Conscientiousness. These higher order traits have been theorized to relate to individual differences in the functioning of the dopamine and serotonin systems, respectively. As dopamine is associated with exploration and incentive-related action, and serotonin with satiety and constraint, this neuropharmacological trait theory has behavioral implications, which we tested in 307 adults by examining the association of a large number of behavioral acts with multi-informant reports of the metatraits. The frequencies of acts were consistently positively correlated with Plasticity and negatively correlated with Stability. At the broadest level of description, variation in human personality appears to reflect engagement and restraint of behavior.

  7. Contagion and differentiation in unethical behavior: the effect of one bad apple on the barrel.

    Science.gov (United States)

    Gino, Francesca; Ayal, Shahar; Ariely, Dan

    2009-03-01

    In a world where encounters with dishonesty are frequent, it is important to know if exposure to other people's unethical behavior can increase or decrease an individual's dishonesty. In Experiment 1, our confederate cheated ostentatiously by finishing a task impossibly quickly and leaving the room with the maximum reward. In line with social-norms theory, participants' level of unethical behavior increased when the confederate was an in-group member, but decreased when the confederate was an out-group member. In Experiment 2, our confederate instead asked a question about cheating, which merely strengthened the saliency of this possibility. This manipulation decreased the level of unethical behavior among the other group members. These results suggest that individuals' unethicality does not depend on the simple calculations of cost-benefit analysis, but rather depends on the social norms implied by the dishonesty of others and also on the saliency of dishonesty.

  8. Based on database and asp.net technologies, a web platform of scientific data in the casting forces on the mold-fi lling behavior of titanium melts in vertically rotating molds

    Directory of Open Access Journals (Sweden)

    Xu Daming

    2008-11-01

    Full Text Available The vertical centrifugal-casting technique is widely used in the manufacture of various irregularlyshaped castings of advanced structural alloys with thin walls, complex shapes and/or large sizes. These castings are used in the increasing applications in aero-space/aviation industries, human teeth/bone repairs with nearnet shaped components, etc. In a vertically rotating casting system, the mold-filling processes of alloy melts, coupled with solidifi cation-heat transfer, may be much more complicated, because they are driven simultaneously by gravity, centrifugal and Coriolis forces. In the present work, an N-S/VOF-equations-based model, solved using a SOLA-VOF algorithm, under a rotating coordinate system was applied to numerically investigate the impacts of centrifugal and Coriolis forces on metallic melt mold-fi lling processes in different vertical centrifugal-casting configurations with different mold-rotation rates using an authors’ computer-codes system. The computational results show that the Coriolis force may cause remarkable variations in the fl ow patterns in the casting-part-cavities of a large horizontal-section area and directly connected to the sprue via a short ingate in a vertical centrifugalcasting process. A “turn-back” mold-filling technique, which only takes advantage of the centrifugal force in a transient rotating melt system, has been confi rmed to be a rational centrifugal-casting process in order to achieve smooth and layer-by-layer casting-cavities-fi lling control. The simulated mold-fi lling processes of Ti-6Al-4V alloy melt, in a vertical centrifugal-casting system with horizontally-connected plate-casting cavities, show reasonable agreement with experimental results from the literature.

  9. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Ph.D Liu Jincheng

    2010-01-01

    @@ Note: This book consists of five sections: Chapter 1 Introduction, Chapter 2 Grey Iron, Chapter 3 Spheroidal Graphite Cast Iron, Chapter 4 Vermicular Cast Iron, and Chapter 5 White Cast Iron. CHINA FOUNDRY publishes this book in several parts serially, starting from the first issue of 2009.

  10. Evaluation of an improved centrifugal casting machine.

    Science.gov (United States)

    Donovan, T E; White, L E

    1985-05-01

    A Type III gold alloy, a silver-palladium alloy, and a base metal alloy were cast in two different centrifugal casting machines. With the number of complete cast mesh squares as an indicator of castability, the Airspin casting machine produced superior castings with all three alloys. The base metal alloy produced the greatest number of complete squares with both casting machines.

  11. Asymptotic Behavior of Solutions to a Class of Systems of Delay Differential Equations

    Institute of Scientific and Technical Information of China (English)

    Tai Shan YI; Li Hong HUANG

    2007-01-01

    The authors investigate the asymptotic behavior of solutions to a class of systems of delaydifferential equations.It is shown that every bounded solution of such a class of systems tends to aconstant vector as t→∞.Our results improve and extend some corresponding ones already known.

  12. Differential Effects of a Food-Based Conditioned Inhibitor on Food- or Cocaine-Seeking Behavior

    Science.gov (United States)

    Lombas, Andres S.; Kearns, David N.; Weiss, Stanley J.

    2008-01-01

    The present experiment compared the effects of a food-based conditioned inhibitor on food seeking vs. cocaine seeking behavior. In two groups of rats, the A+/AB- Pavlovian conditioned inhibition procedure was used to create a conditioned inhibitor for food. Then, for one group of rats (Food-Food Group), a click stimulus was established as an…

  13. Differential Rearing Alters Forced Swim Test Behavior, Fluoxetine Efficacy, and Post-Test Weight Gain in Male Rats.

    Science.gov (United States)

    Arndt, David L; Peterson, Christy J; Cain, Mary E

    2015-01-01

    Environmental factors play a key role in the etiology of depression. The rodent forced swim test (FST) is commonly used as a preclinical model of depression, with increases in escape-directed behavior reflecting antidepressant effects, and increases in immobility reflecting behavioral despair. Environmental enrichment leads to serotonergic alterations in rats, but it is unknown whether these alterations may influence the efficacy of common antidepressants. Male Sprague-Dawley rats were reared in enriched (EC), standard (SC), or isolated (IC) conditions. Following the rearing period, fluoxetine (10 or 20 mg/kg, i.p.) was administered 23.5 hrs, 5 hrs, and 1 hr before locomotor and FST measures. Following locomotor testing and FST exposure, rats were weighed to assess fluoxetine-, FST-, and environmental condition-induced moderations in weight gain. Results revealed an antidepressant effect of environmental enrichment and a depressant effect of isolation. Regardless of significant fluoxetine effects on locomotor activity, fluoxetine generally decreased swimming and increased immobility in all three environmental conditions, with IC-fluoxetine (10 mg/kg) rats and EC-fluoxetine (20 mg/kg) rats swimming less than vehicle counterparts. Subchronic 20 mg/kg fluoxetine also induced significant weight loss, and differential rearing appeared to moderate weight gain following FST stress. These results suggest that differential rearing has the ability to alter FST behaviors, fluoxetine efficacy, and post-stressor well-being. Moreover, 20 mg/kg fluoxetine, administered subchronically, may lead to atypical effects of those commonly observed in the FST, highlighting the importance and impact of both environmental condition and dosing regimen in common animal models of depression.

  14. The casting of western sculpture during the XIXth century: sand casting versus lost wax casting

    NARCIS (Netherlands)

    Beentjes, T.P.C.

    2014-01-01

    This paper will discuss research into bronze casting techniques as practiced during the XIXth and early XXth century. Both natural sand casting (fonte au sable naturel) and lost wax casting (fonte à la cire perdue) were employed during this period and sometimes rivalled for commissions. Before the X

  15. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Chapter 3 Spheroidal Graphite Cast Iron(I) Spheroidal Graphite Cast Iron, SG iron in short, refers to the cast iron in which graphite precipitates as spheroidal shape during solidification of liquid iron. The graphite in common commercial cast iron can only be changed from flake to spheroidal shape by spheroidising treatment. Since spheroidal graphite reduces the cutting effect of stress concentration, the metal matrix strength of SG iron can be applied around 70%-90%, thus the mechanical property of SG iron is significantly superior to other cast irons;even the tensile strength of SG iron is higher than that carbon steel.

  16. Modeling Long-term Behavior of Stock Market Prices Using Differential Equations

    Science.gov (United States)

    Yang, Xiaoxiang; Zhao, Conan; Mazilu, Irina

    2015-03-01

    Due to incomplete information available in the market and uncertainties associated with the price determination process, the stock prices fluctuate randomly during a short period of time. In the long run, however, certain economic factors, such as the interest rate, the inflation rate, and the company's revenue growth rate, will cause a gradual shift in the stock price. Thus, in this paper, a differential equation model has been constructed in order to study the effects of these factors on the stock prices. The model obtained accurately describes the general trends in the AAPL and XOM stock price changes over the last ten years.

  17. Long Time Behavior for a System of Differential Equations with Non-Lipschitzian Nonlinearities

    Directory of Open Access Journals (Sweden)

    Nasser-Eddine Tatar

    2014-01-01

    Full Text Available We consider a general system of nonlinear ordinary differential equations of first order. The nonlinearities involve distributed delays in addition to the states. In turn, the distributed delays involve nonlinear functions of the different variables and states. An explicit bound for solutions is obtained under some rather reasonable conditions. Several special cases of this system may be found in neural network theory. As a direct application of our result it is shown how to obtain global existence and, more importantly, convergence to zero at an exponential rate in a certain norm. All these nonlinearities (including the activation functions may be non-Lipschitz and unbounded.

  18. Population dynamics under selection and mutation: Long-time behavior for differential equations in measure spaces

    Science.gov (United States)

    Ackleh, Azmy S.; Cleveland, John; Thieme, Horst R.

    2016-07-01

    We study the long-time behavior of solutions to a measure-valued selection-mutation model that we formulated in [14]. We establish permanence results for the full model, and we study the limiting behavior even when there is more than one strategy of a given fitness; a case that arises in applications. We show that for the pure selection case the solution of the dynamical system converges to a Dirac measure centered at the fittest strategy class provided that the support of the initial measure contains a fittest strategy; thus we term this Dirac measure an Asymptotically Stable Strategy. We also show that when the strategy space is discrete, the selection-mutation model with small mutation has a locally asymptotically stable equilibrium that attracts all initial conditions that are positive at the fittest strategy.

  19. Differential Effects of TRPA and TRPV Channels on Behaviors of Caenorhabditis elegans

    Science.gov (United States)

    Thies, Jennifer; Neutzler, Vanessa; O’Leary, Fidelma; Liu, He

    2016-01-01

    TRPA and TRPV ion channels are members of the transient receptor potential (TRP) cation channel superfamily, which mediates various sensory transductions. In Caenorhabditis elegans, the TRPV channels are known to affect chemosensation, while the TRPA-1 channel is associated with thermosensation and mechanosensation. We examined thermosensation, chemosensation, and osmosensation in strains lacking TRPA-1 or TRPV channels. We found that TRPV channel knockout worms exhibited similar behavioral deficits associated with thermotaxis as the TRPA-1 channel knockout, suggesting a dual role for TRPV channels. In contrast, chemosensation responses, assessed by both avoidance reversal behavior and NaCl osmosensation, were dependent on TRPV channels but seemed independent of TRPA-1 channel. Our findings suggest that, in addition to TRPA-1 channel, TRPV channels are necessary for thermotaxis and may activate, or modulate, the function of TRPA-1 channels. In contrast, TRPA-1 channels do not have a dual responsibility, as they have no functional role in odorant avoidance or osmosensation. PMID:27168724

  20. Effects of ecological differentiation on Lotka-Volterra systems for species with behavioral adaptation and variable growth rates.

    Science.gov (United States)

    Lacitignola, D; Tebaldi, C

    2005-03-01

    We study the properties of a n2-dimensional Lotka-Volterra system describing competing species that include behaviorally adaptive abilities. We indicate as behavioral adaptation a mechanism, based on a kind of learning, which is not viewed in the evolutionary sense but is intended to occur over shorter time scales. We consider a competitive adaptive n species Lotka-Volterra system, n > or = 3, in which one species is made ecologically differentiated with respect to the others by carrying capacity and intrinsic growth rate. The symmetry properties of the system and the existence of a certain class of invariant subspaces allow the introduction of a 7-dimensional reduced model, where n appears as a parameter, which gives full account of existence and stability of equilibria in the complete system. The reduced model is effective also in describing the time-dependent regimes for a large range of parameter values. The case in which one species has a strong ecological advantage (i.e. with a carrying capacity higher than the others), but with a varying growth rate, has been analyzed in detail, and time-dependent behaviors have been investigated in the case of adaptive competition among four species. Relevant questions, as species survival/exclusion, are addressed focusing on the role of adaptation. Interesting forms of species coexistence are found (i.e. competitive stable equilibria, periodic oscillations, strange attractors).

  1. Characterization of Ni–Cr alloys using different casting techniques and molds

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wen-Cheng, E-mail: wencchen@fcu.edu.tw [Advanced Medical Devices and Composites Laboratory, Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Teng, Fu-Yuan [Department of Dentistry, Kaohsiung Armed Forces General Hospital, Kaohsiung 802, Taiwan (China); School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Hung, Chun-Cheng [School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Department of Dentistry, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China)

    2014-02-01

    This study differentiated the mechanical properties of nickel–chromium (Ni–Cr) alloys under various casting techniques (different casting molds and casting atmospheres). These techniques were sampled by a sand mold using a centrifugal machine in ambient air (group I) and electromagnetic induction in an automatic argon castimatic casting machine (group II). The specimen casting used a graphite mold by a castimatic casting machine (group III). The characteristics of the Ni–Cr alloys, yield and ultimate tensile strength, bending modulus, microhardness, diffraction phase, grindability, ability to spring back, as well as ground microstructure and pattern under different casting conditions were evaluated. The group III specimens exhibited the highest values in terms of strength, modulus, hardness, and grindability at a grind rate of 500 rpm. Moreover, group III alloys exhibited smaller grain sizes, higher ability to spring back, and greater ductility than those casted by sand investment (groups I and II). The main factor, “casting mold,” significantly influenced all mechanical properties. The graphite mold casting of the Ni–Cr dental alloys in a controlled atmosphere argon casting system provided an excellent combination of high mechanical properties and good ability to spring back, and preserved the ductile properties for application in Ni–Cr porcelain-fused system. The results can offer recommendations to assist a prosthetic technician in selecting the appropriate casting techniques to obtain the desired alloy properties. - Highlights: • Properties of Ni–Cr alloys using various casting techniques are characterized. • Alloys cast by graphite mold exhibited higher recovery angle and more ductility. • Alloys cast by graphite mold exhibited higher strength and grinding rate. • Alloys in this study increase operative room to adjust the precision for prosthesis.

  2. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  3. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.; Wilkening, D. [Columbia Falls Aluminum Co., 2000 Aluminum Dr., Columbia Falls, MT 59912 (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., P.O. Box 1071, Anaconda, MT 59711 (United States)

    1998-12-31

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{sup TM} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast. (orig.) 18 refs.

  4. Phylogenetic analyses of termite post-embryonic sequences illuminate caste and developmental pathway evolution.

    Science.gov (United States)

    Legendre, Frédéric; Whiting, Michael F; Grandcolas, Philippe

    2013-01-01

    Termites are highly eusocial insects with a caste polyphenism (i.e., discontinuous morphological differences between castes) and elaborated behaviors. While the developmental pathways leading to caste occurrence are well-known in many species, the evolutionary origin of these pathways is still obscure. Recent molecular phylogenetic studies suggest multiple independent origins of sterile castes in termites, reviving a 30 years old debate. We demonstrate here that diploid sterile castes ("true" workers) evolved several times independently in this group and that this caste was lost at least once in a lineage with developmentally more flexible workers called pseudergates or "false" workers. We also infer that flexibility in post-embryonic development was acquired multiple times independently during termite evolution. We suggest that focusing on detailed developmental pathways in phylogenetic analyses is essential for elucidating the origin of caste polyphenism in termites.

  5. Influence of Refiner in ZA-12 Alloys During Centrifugal Casting Process

    Science.gov (United States)

    Jyothi, P. N.; Shailesh, Rao A.; Jagath, M. C.; Channakeshavalu, K.

    2014-05-01

    The behavior of the molten melt plays a predominant role in determining the quality cast product. In continuous casting, addition of refiner 1% (Al+Ti+B2) onto the molten metal increases its mechanical properties as a result of the nucleation within the process. In this article, the effect of refiners in the centrifugal casting process was studied. Eutectic ZA-12 alloys were taken for our experiment and cast at various rotational speeds (400 rpm, 600 rpm, and 800 rpm) with and without the addition of refiners. Rather than increase in the solidification rate as in continuous casting, these refiners diminish the solidification rate, which in turn forms an irregular-shaped cast tube. The microstructure and hardness for the entire cast specimen were discussed finally.

  6. Genome-wide and caste-specific DNA methylomes of the ants Camponotus floridanus and Harpegnathos saltator

    DEFF Research Database (Denmark)

    Bonasio, Roberto; Li, Qiye; Lian, Jinmin

    2012-01-01

    Ant societies comprise individuals belonging to different castes characterized by specialized morphologies and behaviors. Because ant embryos can follow different developmental trajectories, epigenetic mechanisms must play a role in caste determination. Ants have a full set of DNA methyltransfera...

  7. The Effects of a Brief Acceptance-based Behavior Therapy vs. Traditional Cognitive Behavior Therapy for Public Speaking Anxiety: Differential Effects on Performance and Verbal Working Memory

    Science.gov (United States)

    Glassman, Lisa Hayley

    ), as well as an improvement in speech performance regardless of intervention received. While not statistically significant, participants who received an acceptance-based intervention exhibited larger improvements in observer-rated speech performance at post-treatment in comparison to tCBT (F (1,21) = 1.91, p =.18, etap2 = .08) such that individuals in the ABBT condition exhibited a considerably greater improvement in observer-rated speech performance than those in the tCBT condition. There was no differential impact of treatment condition on subjective speech anxiety or working memory task performance. Potential mediators and moderators of treatment were also examined. Results provide support for a brief 90-minute intervention for public speaking anxiety, but more research is needed in a study with a larger sample to fully understand the relationship between ABBT strategies and improvements in behavioral performance.

  8. Varying social media post types differentially impacts engagement in a behavioral weight loss intervention.

    Science.gov (United States)

    Hales, Sarah B; Davidson, Charis; Turner-McGrievy, Gabrielle M

    2014-12-01

    The purpose of this study was to examine whether different types of posts differentially affect participant engagement and if engagement with social media enhances weight loss. Data are a subanalysis from a randomized weight loss study with a 4-month follow-up support period via private Facebook groups and monthly meetings. Counselors posted five different post types/week based on social cognitive theory (weight-related, recipes, nutrition information, poll votes, or requests for suggestions). Types of participant engagement (likes, comments/poll votes, and views) were assessed. Poll votes were the most engaging (mean number of votes or comments/poll 14.6 ± 3.4, P Engagement with Facebook was significantly associated with weight loss during the 4-month maintenance period (B = -0.09, P = 0.04). The findings provide evidence for ways to provide social support during weight loss interventions using remote methodology.

  9. Dynamic behaviors of a delay differential equation model of plankton allelopathy

    Science.gov (United States)

    Chen, Fengde; Li, Zhong; Chen, Xiaoxing; Laitochova, Jitka

    2007-09-01

    In this paper, we consider a modified delay differential equation model of the growth of n-species of plankton having competitive and allelopathic effects on each other. We first obtain the sufficient conditions which guarantee the permanence of the system. As a corollary, for periodic case, we obtain a set of delay-dependent condition which ensures the existence of at least one positive periodic solution of the system. After that, by means of a suitable Lyapunov functional, sufficient conditions are derived for the global attractivity of the system. For the two-dimensional case, under some suitable assumptions, we prove that one of the components will be driven to extinction while the other will stabilize at a certain solution of a logistic equation. Examples show the feasibility of the main results.

  10. DIFFERENTIAL EFFECTS OF A FOOD-BASED CONDITIONED INHIBITOR ON FOOD- OR COCAINE-SEEKING BEHAVIOR

    OpenAIRE

    Lombas, Andrés S.; Kearns, David N.; Weiss, Stanley J.

    2008-01-01

    The present experiment compared the effects of a food-based conditioned inhibitor on food seeking vs. cocaine seeking behavior. In two groups of rats, the A+/AB− Pavlovian conditioned inhibition procedure was used to create a conditioned inhibitor for food. Then, for one group of rats (Food-Food Group), a click stimulus was established as an operant discriminative stimulus (SD) for food-reinforced lever pressing. In the other group (Food-Cocaine Group), the click was established as an SD for ...

  11. [Casting faults and structural studies on bonded alloys comparing centrifugal castings and vacuum pressure castings].

    Science.gov (United States)

    Fuchs, P; Küfmann, W

    1978-07-01

    The casting processes in use today such as centrifugal casting and vacuum pressure casting were compared with one another. An effort was made to answer the question whether the occurrence of shrink cavities and the mean diameter of the grain of the alloy is dependent on the method of casting. 80 crowns were made by both processes from the baked alloys Degudent Universal, Degudent N and the trial alloy 4437 of the firm Degusa. Slice sections were examined for macro and micro-porosity and the structural appearance was evaluated by linear analysis. Statistical analysis showed that casting faults and casting structure is independent of the method used and their causes must be found in the conditions of casting and the composition of the alloy.

  12. Hot Deformation Behavior of As-Cast 2101 Grade Lean Duplex Stainless Steel and the Associated Changes in Microstructure and Crystallographic Texture

    Science.gov (United States)

    Patra, Sudipta; Ghosh, Abhijit; Singhal, Lokesh Kumar; Podder, Arijit Saha; Sood, Jagmohan; Kumar, Vinod; Chakrabarti, Debalay

    2017-01-01

    The hot deformation behavior of 2101 grade lean duplex stainless steel (DSS, containing 5 wt pct Mn, 0.2 wt pct N, and 1.4 wt pct Ni) and associated microstructural changes within δ-ferrite and austenite ( γ) phases were investigated by hot-compression testing in a GLEEBLE 3500 simulator over a range of deformation temperatures, T def [1073 K to 1373 K (800 °C to 1100 °C)], and applied strains, ɛ (0.25 to 0.80), at a constant true strain rate of 1/s. The microstructural softening inside γ was dictated by discontinuous dynamic recrystallization (DDRX) at a higher T def [1273 K to 1373 K (1000 °C to 1100 °C)], while the same was dictated by continuous dynamic recrystallization (CDRX) at a lower T def (1173 K (900 °C)]. Dynamic recovery (DRV) and CDRX dominated the softening inside δ-ferrite at T def ≥ 1173 K (900 °C). The dynamic recrystallization (DRX) inside δ and γ could not take place upon deformation at 1073 K (800 °C). The average flow stress level increased 2 to 3 times as the T def dropped from 1273 to 1173 K (1000 °C to 900 °C) and finally to 1073 K (800 °C). The average microhardness values taken from δ-ferrite and γ regions of the deformed samples showed a different trend. At T def of 1373 K (1100 °C), microhardness decreased with the increase in strain, while at T def of 1173 K (900 °C), microhardness increased with the increase in strain. The microstructural changes and hardness variation within individual phases of hot-deformed samples are explained in view of the chemical composition of the steel and deformation parameters ( T def and ɛ).

  13. Hot Deformation Behavior of As-Cast 2101 Grade Lean Duplex Stainless Steel and the Associated Changes in Microstructure and Crystallographic Texture

    Science.gov (United States)

    Patra, Sudipta; Ghosh, Abhijit; Singhal, Lokesh Kumar; Podder, Arijit Saha; Sood, Jagmohan; Kumar, Vinod; Chakrabarti, Debalay

    2016-11-01

    The hot deformation behavior of 2101 grade lean duplex stainless steel (DSS, containing 5 wt pct Mn, 0.2 wt pct N, and 1.4 wt pct Ni) and associated microstructural changes within δ-ferrite and austenite (γ) phases were investigated by hot-compression testing in a GLEEBLE 3500 simulator over a range of deformation temperatures, T def [1073 K to 1373 K (800 °C to 1100 °C)], and applied strains, ɛ (0.25 to 0.80), at a constant true strain rate of 1/s. The microstructural softening inside γ was dictated by discontinuous dynamic recrystallization (DDRX) at a higher T def [1273 K to 1373 K (1000 °C to 1100 °C)], while the same was dictated by continuous dynamic recrystallization (CDRX) at a lower T def (1173 K (900 °C)]. Dynamic recovery (DRV) and CDRX dominated the softening inside δ-ferrite at T def ≥ 1173 K (900 °C). The dynamic recrystallization (DRX) inside δ and γ could not take place upon deformation at 1073 K (800 °C). The average flow stress level increased 2 to 3 times as the T def dropped from 1273 to 1173 K (1000 °C to 900 °C) and finally to 1073 K (800 °C). The average microhardness values taken from δ-ferrite and γ regions of the deformed samples showed a different trend. At T def of 1373 K (1100 °C), microhardness decreased with the increase in strain, while at T def of 1173 K (900 °C), microhardness increased with the increase in strain. The microstructural changes and hardness variation within individual phases of hot-deformed samples are explained in view of the chemical composition of the steel and deformation parameters (T def and ɛ).

  14. Differential dynamic behaviors of undulatory nematodes in liquid vs. soft gel environment

    Science.gov (United States)

    Park, Jin-Sung; Shin, Jennifer H.

    2015-03-01

    Caenorhabditis elegans (C. elegans) is an undulatory nematode which exhibits two distinct locomotion types of swimming and crawling. Although in its natural habitat C. elegans lives in complex fluidic environment, our current understanding has been limited to the behavior of C. elegans in a simple Newtonian fluid. Here, we present some experimental results on the penetrating behavior of C. elegans at the interface from liquid to solid environment. Once C. elegans, which otherwise swims freely in a liquid, makes a contact to the solid gel boundary, it begins to penetrate vertically to the surface by changing its stroke motion characterized by a stiffer body shape and a slow stroke frequency. The particle image velocimetry (PIV) analysis reveals the flow streamlines produced by the stroke of worm. For the worm that crawls on a solid surface, we utilize a technique of traction force microscopy (TFM) to find that the crawling nematode forms localized force islands along the body where makes direct contacts to the gel surface. This work was supported by the National Research Foundation (NRF) Grant 2013R1A1A2012420 and 2010-0016886.

  15. Light metal compound casting

    Institute of Scientific and Technical Information of China (English)

    Konrad J.M.PAPIS; Joerg F.LOEFFLER; Peter J.UGGOWITZER

    2009-01-01

    'Compound casting'simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, 'compound casting' of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu-ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3Mg2 and AI12Mg17 IMPs) at the interface of Al-Mg couples was avoided by applying a protec-tive coating to the substrate.

  16. Bimetallic layered castings alloy steel – carbon cast steel

    Directory of Open Access Journals (Sweden)

    T. Wróbel

    2011-01-01

    Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast processso-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. ferritic-pearlitic carbon cast steel, whereas working part (layer is plate of austenitic alloy steel sort X10CrNi 18-8. The ratio of thickness between bearing and working part is 8:1. The quality of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches.

  17. Casting larger polycrystalline silicon ingots

    Energy Technology Data Exchange (ETDEWEB)

    Wohlgemuth, J.; Tomlinson, T.; Cliber, J.; Shea, S.; Narayanan, M.

    1995-08-01

    Solarex has developed and patented a directional solidification casting process specifically designed for photovoltaics. In this process, silicon feedstock is melted in a ceramic crucible and solidified into a large grained semicrystalline silicon ingot. In-house manufacture of low cost, high purity ceramics is a key to the low cost fabrication of Solarex polycrystalline wafers. The casting process is performed in Solarex designed casting stations. The casting operation is computer controlled. There are no moving parts (except for the loading and unloading) so the growth process proceeds with virtually no operator intervention Today Solarex casting stations are used to produce ingots from which 4 bricks, each 11.4 cm by 11.4 cm in cross section, are cut. The stations themselves are physically capable of holding larger ingots, that would yield either: 4 bricks, 15 cm by 15 an; or 9 bricks, 11.4 cm by 11.4 an in cross-section. One of the tasks in the Solarex Cast Polycrystalline Silicon PVMaT Program is to design and modify one of the castings stations to cast these larger ingots. If successful, this effort will increase the production capacity of Solarex`s casting stations by 73% and reduce the labor content for casting by an equivalent percentage.

  18. Promoting Behavioral Regulation in Writing: Differential Effects on Indicators of Writing Performance and Learning Behaviors in 4th Graders with and without Externalizing Behavior

    Directory of Open Access Journals (Sweden)

    Cornelia Glaser

    2010-12-01

    Full Text Available In a writing intervention study with 4th-graders, we examined the effects of behaviour-oriented procedures (specification of behaviour rules and intentions; feedback on desired target behaviour, and self-evaluation of behaviour progress on the writing performance of students with aggressive and hyperactive behaviors. In two classes, 42 students, including 10 students with aggressive and hyperactive behaviors, were randomly assigned to one of two conditions: writing strategies program vs. writing strategies plus behaviour-regulation program. Both programs consisted of four 90-min sessions. In groups of nine to twelve students, all students received a cognitive strategies intervention for writing narratives (Glaser, 2005. At posttest and follow-up assessments (four weeks after the training, aggressive-hyperactive students who had been taught writing strategies in tandem with behaviour-regulation techniques outperformed students with problem behaviours who had not been taught such techniques in strategy-related and holistic measures of writing performance. Students with behaviour problems who had only received the writing strategies instruction gained least from attending the program.

  19. The importance of sulfur for the behavior of highly-siderophile elements during Earth's differentiation

    Science.gov (United States)

    Laurenz, Vera; Rubie, David C.; Frost, Daniel J.; Vogel, Antje K.

    2016-12-01

    The highly siderophile elements (HSEs) are widely used as geochemical tracers for Earth's accretion and core formation history. It is generally considered that core formation strongly depleted the Earth's mantle in HSEs, which were subsequently replenished by a chondritic late veneer. However, open questions remain regarding the origin of suprachondritic Ru/Ir and Pd/Ir ratios that are thought to be characteristic for the primitive upper mantle. In most core-formation models that address the behavior of the HSEs, light elements such as S entering the core have not been taken into account and high P-T experimental data for S-bearing compositions are scarce. Here we present a comprehensive experimental study to investigate the effect of increasing S concentration in the metal on HSE metal-silicate partitioning at 2473 K and 11 GPa. We show that the HSEs become less siderophile with increasing S concentrations in the metal, rendering core-forming metal less efficient in removing the HSEs from the mantle if S is present. Furthermore, we investigated the FeS sulfide-silicate partitioning of the HSEs as a function of pressure (7-21 GPa) and temperature (2373-2673 K). The sulfide-silicate partition coefficient for Pt increases strongly with P, whereas those for Pd, Ru and Ir all decrease. The combined effect is such that above ∼20 GPa Ru becomes less chalcophile than Pt, which is opposite to their behavior in the metal-silicate system where Ru is always more siderophile than Pt. The newly determined experimental results are used in a simple 2-stage core formation model that takes into account the effect of S on the behavior of the HSEs during core formation. Results of this model show that segregation of a sulfide liquid to the core from a mantle with substantial HSE concentrations plays a key role in reproducing Earth's mantle HSE abundances. As Ru and Pd are less chalcophile than Pt and Ir at high P-T, some Ru and Pd remain in the mantle after sulfide segregation

  20. Pavlov's methodological behaviorism as a pre-Socratic contribution of the melding of the differential and experimental psychology.

    Science.gov (United States)

    Furedy, John J

    2003-11-01

    The differential/experimental distinction that Cronbach specified is important because any adequate account of psychological phenomena requires the recognition of the validity of both approaches, and a meaningful melding of the two. This paper suggests that Pavlov's work in psychology, based on earlier traditions of inquiry that can be traced back to the pre-Socratics, provides a potential way of achieving this melding, although such features as systematic rather than anecdotal methods of observation need to be added. Pavlov's methodological behaviorist approach is contrasted with metaphysical behaviorism (as exemplified explicitly in Watson and Skinner, and implicitly in the computer-metaphorical, information-processing explanations employed by current "cognitive" psychology). A common feature of the metaphysical approach is that individual-differences variables like sex are essentially ignored, or relegated to ideological categories such as the treatment of sex as merely a "social construction." Examples of research both before and after the "cognitive revolution" are presented where experimental and differential methods are melded, and individual differences are treated as phenomena worthy of investigation rather than as nuisance factors that merely add to experimental error.

  1. Differential behaviors of tea catechins under thermal processing: Formation of non-enzymatic oligomers.

    Science.gov (United States)

    Fan, Fang-Yuan; Shi, Meng; Nie, Ying; Zhao, Yue; Ye, Jian-Hui; Liang, Yue-Rong

    2016-04-01

    Tea catechins as a member of flavan-3-ols subclass with the same skeleton may behave differentially. This study investigated the chemical conversions of 8 catechins under heat treatment with the involvement of epimerization, hydrolysis and oxidation/condensation reactions. Three reactions were enhanced as temperature increased from 30 °C to 90 °C. The epimerization of non-gallated catechins was favored by epi-configuration but hindered by pyrogallol moiety, and the hydrolysis reaction of gallated catechins was facilitated by pyrogallol moiety. Epicatechin and epigallocatechin had the lowest thermostabilities due to epimerization and oxidation/condensation reactions respectively. Sufficient O2 was not a precondition for the occurrence of chemical conversions of catechins under heat treatment. Non-enzymatic oligomerization occurred to epi type catechins and catechin under heat treatment, and dehydrodicatechins A were mainly responsible for the browning of epicatechin and catechin solutions. The evidence of generation of catechin oligomers provides a novel way to explain sensory change of tea and relevant products during thermal processing.

  2. Differential effect of culture temperature and specific growth rate on CHO cell behavior in chemostat culture.

    Science.gov (United States)

    Vergara, Mauricio; Becerra, Silvana; Berrios, Julio; Osses, Nelson; Reyes, Juan; Rodríguez-Moyá, María; Gonzalez, Ramon; Altamirano, Claudia

    2014-01-01

    Mild hypothermia condition in mammalian cell culture technology has been one of the main focuses of research for the development of breeding strategies to maximize productivity of these production systems. Despite the large number of studies that show positive effects of mild hypothermia on specific productivity of r-proteins, no experimental approach has addressed the indirect effect of lower temperatures on specific cell growth rate, nor how this condition possibly affects less specific productivity of r-proteins. To separately analyze the effects of mild hypothermia and specific growth rate on CHO cell metabolism and recombinant human tissue plasminogen activator productivity as a model system, high dilution rate (0.017 h(-1)) and low dilution rate (0.012 h(-1)) at two cultivation temperatures (37 and 33 °C) were evaluated using chemostat culture. The results showed a positive effect on the specific productivity of r-protein with decreasing specific growth rate at 33 °C. Differential effect was achieved by mild hypothermia on the specific productivity of r-protein, contrary to the evidence reported in batch culture. Interestingly, reduction of metabolism could not be associated with a decrease in culture temperature, but rather with a decrease in specific growth rate.

  3. Differential genetic susceptibility to child risk at birth in predicting observed maternal behavior.

    Directory of Open Access Journals (Sweden)

    Keren Fortuna

    Full Text Available This study examined parenting as a function of child medical risks at birth and parental genotype (dopamine D4 receptor; DRD4. Our hypothesis was that the relation between child risks and later maternal sensitivity would depend on the presence/absence of a genetic variant in the mothers, thus revealing a gene by environment interaction (GXE. Risk at birth was defined by combining risk indices of children's gestational age at birth, birth weight, and admission to the neonatal intensive care unit. The DRD4-III 7-repeat allele was chosen as a relevant genotype as it was recently shown to moderate the effect of environmental stress on parental sensitivity. Mothers of 104 twin pairs provided DNA samples and were observed with their children in a laboratory play session when the children were 3.5 years old. Results indicate that higher levels of risk at birth were associated with less sensitive parenting only among mothers carrying the 7-repeat allele, but not among mothers carrying shorter alleles. Moreover, mothers who are carriers of the 7-repeat allele and whose children scored low on the risk index were observed to have the highest levels of sensitivity. These findings provide evidence for the interactive effects of genes and environment (in this study, children born at higher risk on parenting, and are consistent with a genetic differential susceptibility model of parenting by demonstrating that some parents are inherently more susceptible to environmental influences, both good and bad, than are others.

  4. High Temperature Corrosion of Fe-C-S Cast Irons in Oxidizing and Sulfidizing Atmospheres

    Institute of Scientific and Technical Information of China (English)

    Thuan-Dinh NGUYEN; Dong-Bok LEE

    2008-01-01

    The corrosion behavior of spheroidal graphite and flake graphite cast irons was studied in oxidizing and sulfidizing atmospheres between 600 and 800℃ for 50 h. The corrosion rate in the sulfidizing atmosphere was faster than that in air above 700℃, due to the formation of the Feo.975S sulfide. The corrosion rate of the spheroidal graphite cast iron was similar to that of the flake graphite cast iron.

  5. Mechanisms of masked evaluative priming: Task sets modulate behavioral and electrophysiological priming for picture and words differentially.

    Science.gov (United States)

    Kiefer, Markus; Liegel, Nathalie; Zovko, Monika; Wentura, Dirk

    2016-12-20

    Research with the evaluative priming paradigm has shown that affective evaluation processes reliably influence cognition and behavior, even when triggered outside awareness. However, the precise mechanisms underlying such subliminal evaluative priming effects, response activation vs. semantic processing, are matter of a debate. In the present study, we determined the relative contribution of semantic processing and response activation to masked evaluative priming with pictures and words. To this end, we investigated the modulation of masked pictorial vs. verbal priming by previously activated perceptual versus semantic task sets and assessed the electrophysiological correlates of priming using event-related potential (ERP) recordings. Behavioral and electrophysiological effects showed a differential modulation of pictorial and verbal subliminal priming by previously activated task sets: Pictorial priming was only observed during the perceptual but not during the semantic task set. Verbal priming, in contrast, was found when either task set was activated. Furthermore, only verbal priming was associated with a modulation of the N400 ERP component, an index of semantic processing, whereas a priming-related modulation of earlier ERPs, indexing visuo-motor S-R activation, was found for both picture and words. The results thus demonstrate that different neuro-cognitive processes contribute to unconscious evaluative priming depending on the stimulus format.

  6. Fracture Mechanisms in Steel Castings

    Directory of Open Access Journals (Sweden)

    Z. Stradomski

    2013-07-01

    Full Text Available The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.

  7. The alpha-fetoprotein knock-out mouse model suggests that parental behavior is sexually differentiated under the influence of prenatal estradiol.

    Science.gov (United States)

    Keller, Matthieu; Pawluski, Jodi L; Brock, Olivier; Douhard, Quentin; Bakker, Julie

    2010-04-01

    In rodent species, sexual differentiation of the brain for many reproductive processes depends largely on estradiol. This was recently confirmed again by using the alpha-fetoprotein knockout (AFP-KO) mouse model, which lacks the protective actions of alpha-fetoprotein against maternal estradiol and as a result represents a good model to determine the contribution of prenatal estradiol to the sexual differentiation of the brain and behavior. Female AFP-KO mice were defeminized and masculinized with regard to their neuroendocrine responses as well as sexual behavior. Since parental behavior is also strongly sexually differentiated in mice, we used the AFP-KO mouse model here to ask whether parental responses are differentiated prenatally under the influence of estradiol. It was found that AFP-KO females showed longer latencies to retrieve pups to the nest and also exhibited lower levels of crouching over the pups in the nest in comparison to WT females. In fact, they resembled males (WT and AFP-KO). Other measures of maternal behavior, for example the incidence of infanticide, tended to be higher in AFP-KO females than in WT females but this increase failed to reach statistical significance. The deficits observed in parental behavior of AFP-KO females could not be explained by any changes in olfactory function, novelty recognition or anxiety. Thus our results suggest that prenatal estradiol defeminizes the parental brain in mice.

  8. Exogenous attention to fear: Differential behavioral and neural responses to snakes and spiders.

    Science.gov (United States)

    Soares, Sandra C; Kessel, Dominique; Hernández-Lorca, María; García-Rubio, María J; Rodrigues, Paulo; Gomes, Nuno; Carretié, Luis

    2017-03-06

    Research has consistently shown that threat stimuli automatically attract attention in order to activate the defensive response systems. Recent findings have provided evidence that snakes tuned the visual system of evolving primates for their astute detection, particularly under challenging perceptual conditions. The goal of the present study was to measure behavioral and electrophysiological indices of exogenous attention to snakes, compared with spiders - matched for rated fear levels but for which sources of natural selection are less well grounded, and to innocuous animals (birds), which were presented as distracters, while participants were engaged in a letter discrimination task. Duration of stimuli, consisting in a letter string and a concurrent distracter, was either presented for 180 or 360ms to explore if the stimulus duration was a modulating effect of snakes in capturing attention. Results showed a specific early (P1) exogenous attention-related brain potential with maximal amplitude to snakes in both durations, which was followed by an enhanced late attention-related potential (LPP) showing enhanced amplitudes to spiders, particularly under the longer exposure durations. These results suggest that exogenous attention to different classes of threat stimuli follows a gradual process, with the most evolutionary-driven stimulus, i.e., snakes, being more efficient at attracting early exogenous attention, thus more dependent on bottom-up processes.

  9. Free-Operant Field Experiences: Differentially Reinforcing Successive Approximations to Behavior Analysis through a ShaperSpace

    Directory of Open Access Journals (Sweden)

    Lee L . Mason

    2016-11-01

    Full Text Available Over the past few years an increasing number of schools and community organizations have developed transformative learning spaces referred to as “MakerSpaces” for research and training purposes. MakerSpaces are organizations in which members sharing similar interests in science, technology, engineering, and math (STEM gather to work on self-selected projects. Proponents of MakerSpaces highlight the implicit benefits arising from participants’ increased engagement with complex technical content in a voluntary, authentic context. We extend the MakerSpace concept to applications of training special education teachers to address the needs of students with Autism Spectrum Disorder (ASD. Applied behavior analysis (ABA has vast empirical support for treating ASD. We believe the MakerSpace model provides a platform for developing a new generation of special education teachers. However, rather than making novel products, the focus is on shaping the behavior-analytic repertoires of special education teachers. In the field of ABA, the term “shaping” describes the differential reinforcement of successive approximations to a target behavior. Accordingly, we propose the name ShaperSpace to describe a novel clinical training approach to developing special education teachers who employ research-validated interventions for individuals with ASD. The supervision model described in this article is provided, not as a recommendation, but as an exemplar that has developed over four years’ contingency shaping and continues to be refined. We appeal to the reader to consider the ShaperSpace as a starting point from which skills developed through free-operant field experiences will ultimately be shaped and selected by the naturally occurring contingencies of the environment.

  10. Rhabdoid differentiation is associated with aggressive behavior in renal cell carcinoma: a clinicopathologic analysis of 76 cases with clinical follow-up.

    Science.gov (United States)

    Przybycin, Christopher G; McKenney, Jesse K; Reynolds, Jordan P; Campbell, Steven; Zhou, Ming; Karafa, Matthew T; Magi-Galluzzi, Cristina

    2014-09-01

    Rhabdoid differentiation has been associated with aggressive behavior in carcinomas from different organ systems. A recent consensus statement of the International Society of Urological Pathology (ISUP), in addition to proposing a nucleolar grading system (ISUP grade) for renal cell carcinoma (RCC) to replace the Fuhrman system, recommended reporting the presence of rhabdoid differentiation in RCC and considering tumors with rhabdoid differentiation to be ISUP grade 4. Although it has been shown that rhabdoid differentiation is associated with increased grade and stage of RCC, it has not been fully demonstrated whether it has an adverse effect independent of this association with increased grade and stage. We provide the largest clinicopathologic analysis of RCC with rhabdoid differentiation to date (76 cases), including characterization of metastatic disease. In addition, by constructing a multivariable model including tumor grade, stage, necrosis, and distant metastasis to compare a series of 49 clear cell RCC with rhabdoid differentiation with a cohort of 41 clear cell RCCs without rhabdoid differentiation, we demonstrate that the presence of rhabdoid differentiation in clear cell RCC confers an increased risk of death (hazard ratio=5.25; 95% confidence interval, 2.1-14.3) independent of these other adverse prognostic factors. These findings underscore the significance of rhabdoid differentiation in RCC as an adverse prognostic factor and support the recent reporting and grading recommendations of the ISUP.

  11. COMPARING THE EFFECTS OF DIFFERENTIAL REINFORCEMENT OF OTHER BEHAVIOR AND RESPONSE-COST CONTINGENCIES ON TICS IN YOUTH WITH TOURETTE SYNDROME

    OpenAIRE

    Capriotti, Matthew R.; Brandt, Bryan C.; Ricketts, Emily J.; Espil, Flint M; Woods, Douglas W

    2012-01-01

    Tics are rapid, repetitive, stereotyped movements or vocalizations that arise from neurobiological dysfunction and are influenced by environmental factors. Although persons with tic disorders often experience aversive social reactions in response to tics, little is known about the behavioral effects of such consequences. Along several dimensions, the present study compared the effects of two treatments on tics: response cost (RC) and differential reinforcement of other behavior (DRO). Four ch...

  12. Fish gut microbiota analysis differentiates physiology and behavior of invasive Asian carp and indigenous American fish.

    Science.gov (United States)

    Ye, Lin; Amberg, Jon; Chapman, Duane; Gaikowski, Mark; Liu, Wen-Tso

    2014-03-01

    Gut microbiota of invasive Asian silver carp (SVCP) and indigenous planktivorous gizzard shad (GZSD) in Mississippi river basin were compared using 16S rRNA gene pyrosequencing. Analysis of more than 440 000 quality-filtered sequences obtained from the foregut and hindgut of GZSD and SVCP revealed high microbial diversity in these samples. GZSD hindgut (GZSD_H) samples (n=23) with >7000 operational taxonomy units (OTUs) exhibited the highest alpha-diversity indices followed by SVCP foregut (n=15), GZSD foregut (n=9) and SVCP hindgut (SVCP_H) (n=24). UniFrac distance-based non-metric multidimensional scaling (NMDS) analysis showed that the microbiota of GZSD_H and SVCP_H were clearly separated into two clusters: samples in the GZSD cluster were observed to vary by sampling location and samples in the SVCP cluster by sampling date. NMDS further revealed distinct microbial community between foregut to hindgut for individual GZSD and SVCP. Cyanobacteria, Proteobacteria, Actinobacteria and Bacteroidetes were detected as the predominant phyla regardless of fish or gut type. The high abundance of Cyanobacteria observed was possibly supported by their role as the fish's major food source. Furthermore, unique and shared OTUs and OTUs in each gut type were identified, three OTUs from the order Bacteroidales, the genus Bacillariophyta and the genus Clostridium were found significantly more abundant in GZSD_H (14.9-22.8%) than in SVCP_H (0.13-4.1%) samples. These differences were presumably caused by the differences in the type of food sources including bacteria ingested, the gut morphology and digestion, and the physiological behavior between GZSD and SVCP.

  13. Fish gut microbiota analysis differentiates physiology and behavior of invasive Asian carp and indigenous American fish

    Science.gov (United States)

    Ye, Lin; Amberg, Jon J.; Chapman, Duane C.; Gaikowski, Mark P.; Liu, Wen-Tso

    2014-01-01

    Gut microbiota of invasive Asian silver carp (SVCP) and indigenous planktivorous gizzard shad (GZSD) in Mississippi river basin were compared using 16S rRNA gene pyrosequencing. Analysis of more than 440 000 quality-filtered sequences obtained from the foregut and hindgut of GZSD and SVCP revealed high microbial diversity in these samples. GZSD hindgut (GZSD_H) samples (n=23) with >7000 operational taxonomy units (OTUs) exhibited the highest alpha-diversity indices followed by SVCP foregut (n=15), GZSD foregut (n=9) and SVCP hindgut (SVCP_H) (n=24). UniFrac distance-based non-metric multidimensional scaling (NMDS) analysis showed that the microbiota of GZSD_H and SVCP_H were clearly separated into two clusters: samples in the GZSD cluster were observed to vary by sampling location and samples in the SVCP cluster by sampling date. NMDS further revealed distinct microbial community between foregut to hindgut for individual GZSD and SVCP. Cyanobacteria, Proteobacteria, Actinobacteria and Bacteroidetes were detected as the predominant phyla regardless of fish or gut type. The high abundance of Cyanobacteria observed was possibly supported by their role as the fish’s major food source. Furthermore, unique and shared OTUs and OTUs in each gut type were identified, three OTUs from the order Bacteroidales, the genus Bacillariophyta and the genus Clostridium were found significantly more abundant in GZSD_H (14.9–22.8%) than in SVCP_H (0.13–4.1%) samples. These differences were presumably caused by the differences in the type of food sources including bacteria ingested, the gut morphology and digestion, and the physiological behavior between GZSD and SVCP.

  14. Colour Metallography of Cast Iron Chapter 1 Introduction (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2009-01-01

    @@ 1.5 Colour metallography technique of cast iron Colour metallography possesses better differentiation ability and is more sensitive to segregation, grain orientation and stress state than black-white metallography. It adds functions to traditional metallography and displays wide application perspectives.

  15. Dry sliding wear behavior of stir cast AA6061-T6/AlNp composite%搅拌铸造AA6061-T6/AlNp复合材料的干滑动磨损行为

    Institute of Scientific and Technical Information of China (English)

    B. ASHOK KUMAR; N. MURUGAN; I. DINAHARAN

    2014-01-01

    以 AA6061为基体、AlN 颗粒为增强体,采用搅拌铸造工艺得到 AA6061-T6/AlNp复合材料,研究了AA6061-T6/AlNp复合材料的干滑动磨损行为。开发回归模型来预测复合材料的磨损率。采用四因素、五水平的正交实验进行优化。实验因素包括滑动速度、滑动距离、荷载、增强体 AlN 颗粒的质量分数。采用 SYSTAT 12软件和统计工具,如方差分析(方差分析)和 t 实验,验证回归模型。结果表明,开发的回归模型可以有效预测复合材料的磨损率,置信度达95%。采用回归模型,并依据磨损表面形貌分析,预测实验因素对 AA6061-T6/AlNp复合材料磨损率的影响。回归模型预测结果表明,复合材料的磨损率随着增强体AlN质量分数的增加而降低,随着滑动速度、滑动距离、荷载的增加而增加。%The dry sliding wear behavior of AA6061 matrix composite reinforced with aluminium nitride particles (AlN) produced by stir casting process was investigated. A regression model was developed to predict the wear rate of the prepared composite. A four-factor, five-level central composite rotatable design matrix was used to minimize the number of experimental runs. The factors considered in this study were sliding velocity, sliding distance, normal load and mass fraction of AlN reinforcement in the matrix. The developed regression model was validated by statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student’s t test. It was found that the developed regression model could be effectively used to predict the wear rate at 95% confidence level. The influence of these factors on wear rate of AA6061/AlNp composite was analyzed using the developed regression model and predicted trends were discussed with the aid of worn surface morphologies. The regression model indicated that the wear rate of cast AA6061/AlNp composite decreased with an increase in the mass fraction

  16. Properties of polylactide inks for solvent-cast printing of three-dimensional freeform microstructures.

    Science.gov (United States)

    Guo, Shuang-Zhuang; Heuzey, Marie-Claude; Therriault, Daniel

    2014-02-01

    Solvent-cast printing is a highly versatile microfabrication technique that can be used to construct various geometries such as filaments, towers, scaffolds, and freeform circular spirals by the robotic deposition of a polymer solution ink onto a moving stage. In this work, we have performed a comprehensive characterization of the solvent-cast printing process using polylactide (PLA) solutions by analyzing the flow behavior of the solutions, the solvent evaporation kinetics, and the effect of process-related parameters on the crystallization of the extruded filaments. Rotational rheometry at low to moderate shear rates showed a nearly Newtonian behavior of the PLA solutions, while capillary flow analysis based on process-related data indicated shear thinning at high shear rates. Solvent vaporization tests suggested that the internal diffusion of the solvent through the filaments controlled the solvent removal of the extrudates. Different kinds of three-dimensional (3D) structures including a layer-by-layer tower, nine-layer scaffold, and freeform spiral were fabricated, and a processing map was given to show the proper ranges of process-related parameters (i.e., polymer content, applied pressure, nozzle diameter, and robot velocity) for the different geometries. The results of differential scanning calorimetry revealed that slow solvent evaporation could increase the ability of PLA to complete its crystallization process during the filament drying stage. The method developed here offers a new perspective for manufacturing complex structures from polymer solutions and provides guidelines to optimize the various parameters for 3D geometry fabrication.

  17. Development of Refractories for Continuous Casting

    Institute of Scientific and Technical Information of China (English)

    TIAN Shouxin; JIN Congjin; YAO Jinfu; LI Zeya

    2004-01-01

    The paper introduces refractories for continuous casting, especially, refractories for continuous casting for clean steel in baosteel. Developing direction of refractories for continuous casting has been pointed out to satisfy the new metallurgical operating practice.

  18. Segregation in cast products

    Indian Academy of Sciences (India)

    A Ghosh

    2001-02-01

    Microsegregation gets eliminated significantly if subsequent hot working and/or annealing are done on cast products. Macrosegregation however persists, causing problems in quality, and hence, has to be attended to. Microsegregation is a consequence of rejection of solutes by the solid into the interdendritic liquid. Scheil’s equation is mostly employed. However, other equations have been proposed, which take into account diffusion in solid phase and/or incomplete mixing in liquid. Macrosegregation results from movements of microsegregated regions over macroscopic distances due to motion of liquid and free crystals. Motion of impure interdendritic liquid causes regions of positive macrosegregation, whereas purer solid crystals yield negative macrosegregation. Flow of interdendritic liquid is primarily natural convection due to thermal and solutal buoyancy, and partly forced convection due to suction by shrinkage cavity formation etc. The present paper briefly deals with fundamentals of the above and contains some recent studies as well. Experimental investigations in molten alloys do not allow visualization of the complex flow pattern as well as other phenomena, such as dendrite-tip detachment. Experiments with room temperature analogues, and mathematical modelling have supplemented these efforts. However, the complexity of the phenomena demands simplifying assumptions. The agreement with experimental data is mostly qualitative. The paper also briefly discusses centreline macrosegregation during continuous casting of steel, methods to avoid it, and the, importance of early columnar-to-equiaxed transition (CET) as well as the fundamentals of CET.

  19. Biomaterials by freeze casting.

    Science.gov (United States)

    Wegst, Ulrike G K; Schecter, Matthew; Donius, Amalie E; Hunger, Philipp M

    2010-04-28

    The functional requirements for synthetic tissue substitutes appear deceptively simple: they should provide a porous matrix with interconnecting porosity and surface properties that promote rapid tissue ingrowth; at the same time, they should possess sufficient stiffness, strength and toughness to prevent crushing under physiological loads until full integration and healing are reached. Despite extensive efforts and first encouraging results, current biomaterials for tissue regeneration tend to suffer common limitations: insufficient tissue-material interaction and an inherent lack of strength and toughness associated with porosity. The challenge persists to synthesize materials that mimic both structure and mechanical performance of the natural tissue and permit strong tissue-implant interfaces to be formed. In the case of bone substitute materials, for example, the goal is to engineer high-performance composites with effective properties that, similar to natural mineralized tissue, exceed by orders of magnitude the properties of its constituents. It is still difficult with current technology to emulate in synthetic biomaterials multi-level hierarchical composite structures that are thought to be the origin of the observed mechanical property amplification in biological materials. Freeze casting permits to manufacture such complex, hybrid materials through excellent control of structural and mechanical properties. As a processing technique for the manufacture of biomaterials, freeze casting therefore has great promise.

  20. Evaluation of the Inertness of Investment Casting Molds Using Both Sessile Drop and Centrifugal Casting Methods

    Science.gov (United States)

    Cheng, Xu; Yuan, Chen; Green, Nick; Withey, Paul

    2013-02-01

    The investment casting process is an economic production method for engineering components in TiAl-based alloys and offers the benefits of a near net-shaped component with a good surface finish. An investigation was undertaken to develop three new face coat systems based on yttria, but with better sintering properties. These face coat systems were mainly based on an yttria-alumina-zirconia system (Y2O3-0.5 wt pct Al2O3-0.5 wt pct ZrO2), an yttria-fluoride system (Y2O3-0.15 wt pct YF3), and an yttria-boride system (Y2O3-0.15 wt pct B2O3). After sintering, the chemical inertness of the face coat was first tested and analyzed using a sessile drop test through the metal wetting behavioral change for each face coat surface. Then, the interactions between the shell and metal were studied by centrifugal investment casting TiAl bars. Although the sintering aids in yttria can decrease the chemical inertness of the face coat, the thickness of the interaction layer in the casting was less than 10 μm; therefore, these face coats still can be possible face coat materials for investment casting TiAl alloys.

  1. Education and Caste in India

    Science.gov (United States)

    Chauhan, Chandra Pal Singh

    2008-01-01

    This paper analyses the policy of reservation for lower castes in India. This policy is similar to that of affirmative action in the United States. The paper provides a brief overview of the caste system and discusses the types of groups that are eligible for reservation, based on data from government reports. The stance of this paper is that…

  2. Theory of batchwise centrifugal casting

    NARCIS (Netherlands)

    Biesheuvel, P. Maarten; Nijmeijer, Arian; Verweij, Henk

    1998-01-01

    In batchwise centrifugal casting a cylindrical mold is filled with suspension and rotated rapidly around its axis. This results in the movement of the particulate phase toward the cylinder wall and the formation of a tubular cast. Theory is presented for particle transport in the suspension phase an

  3. Lost Foam Casting in China

    Institute of Scientific and Technical Information of China (English)

    YE Sheng-ping; WU Zhi-chao

    2006-01-01

    @@ 1. Lost Foam Casting Committee of Foundry Institution of Chinese Mechanical Engineering Society (FICMES) From the beginning of the 1990s, China entered a research and expansion climax in lost foam casting technology realm after the United States, Germany, and Japan etc.

  4. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2009-01-01

    @@ This book consists of five sections:Chapter 1 Introduction,Chapter 2 Grey Iron,Chapter 3 Ductile Iron,Chapter 4Vermicular Cast Iron,and Chapter 5 White Cast Iron. CHINA FOUNDRY publishs this book in several parts serially,starting from the first issue of 2009.

  5. Nonmodal phenomena in differentially rotating dusty plasmas

    Science.gov (United States)

    Poedts, Stefaan; Rogava, Andria D.

    2000-10-01

    In this paper the foundation is layed for the nonmodal investigation of velocity shear induced phenomena in a differentially rotating flow of a dusty plasma. The simplest case of nonmagnetized flow is considered. It is shown that, together with the innate properties of the dusty plasma, the presence of differential rotation, Coriolis forces, and self-gravity casts a considerable richness on the nonmodal dynamics of linear perturbations in the flow. In particular: (i) dust-acoustic waves acquire the ability to extract energy from the mean flow and (ii) shear-induced, nonperiodic modes of collective plasma behavior-shear-dust-acoustic vortices-are generated. The presence of self-gravity and the nonzero Coriolis parameter (``epicyclic shaking'') makes these collective modes transiently unstable. .

  6. Numerical Simulation and Cold Modeling experiments on Centrifugal Casting

    Science.gov (United States)

    Keerthiprasad, Kestur Sadashivaiah; Murali, Mysore Seetharam; Mukunda, Pudukottah Gopaliengar; Majumdar, Sekhar

    2011-02-01

    In a centrifugal casting process, the fluid flow eventually determines the quality and characteristics of the final product. It is difficult to study the fluid behavior here because of the opaque nature of melt and mold. In the current investigation, numerical simulations of the flow field and visualization experiments on cold models have been carried out for a centrifugal casting system using horizontal molds and fluids of different viscosities to study the effect of different process variables on the flow pattern. The effects of the thickness of the cylindrical fluid annulus formed inside the mold and the effects of fluid viscosity, diameter, and rotational speed of the mold on the hollow fluid cylinder formation process have been investigated. The numerical simulation results are compared with corresponding data obtained from the cold modeling experiments. The influence of rotational speed in a real-life centrifugal casting system has also been studied using an aluminum-silicon alloy. Cylinders of different thicknesses are cast at different rotational speeds, and the flow patterns observed visually in the actual castings are found to be similar to those recorded in the corresponding cold modeling experiments. Reasonable agreement is observed between the results of numerical simulation and the results of cold modeling experiments with different fluids. The visualization study on the hollow cylinders produced in an actual centrifugal casting process also confirm the conclusions arrived at from the cold modeling experiments and numerical simulation in a qualitative sense.

  7. Behavioral, ecological and genetic differentiation in an open environment--a study of a mysid population in the Baltic Sea.

    Science.gov (United States)

    Ogonowski, Martin; Duberg, Jon; Hansson, Sture; Gorokhova, Elena

    2013-01-01

    Diel vertical migration (DVM) is often assumed to encompass an entire population. However, bimodal nighttime vertical distributions have been observed in various taxa. Mysid shrimp populations also display this pattern with one group concentrated in the pelagia and the other near the bottom. This may indicate alternative migratory strategies, resembling the seasonal partial migrations seen in birds, fishes and amphibians, where only a subset of the population migrates. To assess the persistence of these alternative strategies, we analyzed the nitrogen and carbon stable isotope signatures (as proxies for diet), biochemical indices (as proxies for growth condition), and genetic population divergence in the Baltic mysid Mysis salemaai collected at night in the pelagia and close to the bottom. Stable isotope signatures were significantly different between migrants (pelagic samples) and residents (benthic samples), indicating persistent diet differences, with pelagic mysids having a more uniform and carnivorous diet. Sequencing of the mitochondrial cytochrome subunit I (COI) gene showed genetic differentiation attributable to geographic location but not between benthic and pelagic groups. Divergent migration strategies were however supported by significantly lower gene flow between benthic populations indicating that these groups have a lower predisposition for horizontal migrations compared to pelagic ones. Different migration strategies did not convey measurable growth benefits as pelagic and benthic mysids had similar growth condition indices. Thus, the combination of ecological, biochemical and genetic markers indicate that this partial migration may be a plastic behavioral trait that yields equal growth benefits.

  8. Thermal and structural behavior of dioctadecyldimethylammonium bromide dispersions studied by differential scanning calorimetry and X-ray scattering.

    Directory of Open Access Journals (Sweden)

    Eloi Feitosa

    Full Text Available Dioctadecyldimethylammonium bromide (DODAB is a double chain cationic lipid, which assembles as bilayer structures in aqueous solution. The precise structures formed depend on, e.g., lipid concentration and temperature. We here combine differential scanning calorimetry (DSC and X-ray scattering (SAXS and WAXS to investigate the thermal and structural behavior of up to 120 mM DODAB in water within the temperature range 1-70 °C. Below 1 mM, this system is dominated by unilamellar vesicles (ULVs. Between 1 and 65 mM, ULVs and multilamellar structures (MLSs co-exist, while above 65 mM, the MLSs are the preferred structure. Depending on temperature, DSC and X-ray data show that the vesicles can be either in the subgel (SG, gel, or liquid crystalline (LC state, while the MLSs (with lattice distance d = 36.7 Å consist of interdigitated lamellae in the SG state, and ULVs in the LC state (no Bragg peak. Critical temperatures related to the thermal transitions of these bilayer structures obtained in the heating and cooling modes are reported, together with the corresponding transition enthalpies.

  9. Behavioral, ecological and genetic differentiation in an open environment--a study of a mysid population in the Baltic Sea.

    Directory of Open Access Journals (Sweden)

    Martin Ogonowski

    Full Text Available Diel vertical migration (DVM is often assumed to encompass an entire population. However, bimodal nighttime vertical distributions have been observed in various taxa. Mysid shrimp populations also display this pattern with one group concentrated in the pelagia and the other near the bottom. This may indicate alternative migratory strategies, resembling the seasonal partial migrations seen in birds, fishes and amphibians, where only a subset of the population migrates. To assess the persistence of these alternative strategies, we analyzed the nitrogen and carbon stable isotope signatures (as proxies for diet, biochemical indices (as proxies for growth condition, and genetic population divergence in the Baltic mysid Mysis salemaai collected at night in the pelagia and close to the bottom. Stable isotope signatures were significantly different between migrants (pelagic samples and residents (benthic samples, indicating persistent diet differences, with pelagic mysids having a more uniform and carnivorous diet. Sequencing of the mitochondrial cytochrome subunit I (COI gene showed genetic differentiation attributable to geographic location but not between benthic and pelagic groups. Divergent migration strategies were however supported by significantly lower gene flow between benthic populations indicating that these groups have a lower predisposition for horizontal migrations compared to pelagic ones. Different migration strategies did not convey measurable growth benefits as pelagic and benthic mysids had similar growth condition indices. Thus, the combination of ecological, biochemical and genetic markers indicate that this partial migration may be a plastic behavioral trait that yields equal growth benefits.

  10. Influence of rare earth elements on solidification behavior of a high speed steel for roll using differential scanning calorimetry

    Institute of Scientific and Technical Information of China (English)

    WANG Mingjia; CHEN Lei; WANG Zixi; BAO Er

    2011-01-01

    The influence of rare earths (RE) on solidification behavior of a high speed steel for roll was investigated by using differential scanning calorimetry (DSC) in combination of microstructure analysis.It was found that the sequence of solidification was L→γ,L→γ+MC,L→γ+M2C,L→γ+M6C,respectively.The start temperature and the latent heat liberated by unit mass of L→γ and L→γ+MC increased with increase of RE addition,indicating that RE could trigger the crystallization of the primary γ and the MC carbide more effectively.The promoting effect of RE on the heterogeneous nucleation was believed to be an important cause of this effect.Grain refinement,discontinuous network of eutectic carbides and disperse and finer MC were observed in the samples with RE addition,moreover,RES could act as the heterogeneous nucleus of the MC.RE addition was favorable for stable M6C at the expense of the metastable M2C.

  11. Differential efficacy of cognitive-behavioral therapy and pharmacological treatments for pediatric obsessive-compulsive disorder: a meta-analysis.

    Science.gov (United States)

    Sánchez-Meca, Julio; Rosa-Alcázar, Ana I; Iniesta-Sepúlveda, Marina; Rosa-Alcázar, Angel

    2014-01-01

    The aim of this paper is to present a meta-analysis about the differential efficacy of cognitive-behavioral therapy (CBT), pharmacological and combined treatment for pediatric obsessive-compulsive disorder (OCD). The literature research and the application of the inclusion criteria enabled us to locate 18 studies, yielding a total of 24 independent comparisons between a treated (10 pharmacological, 11 CBT, and 3 combined interventions) and a control group. All types of interventions were efficacious in reducing obsessive-compulsive symptoms, with effect sizes adjusted by the type of control group of d=1.203 for CBT, d=0.745 for pharmacological treatments, and d=1.704 for mixed treatments. Depression, anxiety and other secondary responses were also improved, especially with CBT interventions. The analysis of moderator variables showed that the CBT protocol and the total of intervention hours exhibited a significant influence on the effect size. Within pharmacological treatment, clomipramine (d=1.305) was more efficacious than selective serotonin reuptake inhibitors (d=0.644), but its adverse effects were more severe. Finally, the clinical implications of the results are discussed.

  12. Hygroscopic behavior of partially volatilized coastal marine aerosols using the volatilization and humidification tandem differential mobility analyzer technique

    Science.gov (United States)

    Johnson, G. R.; Ristovski, Z. D.; D'Anna, B.; Morawska, L.

    2005-10-01

    Coastal marine nucleation, Aitken, and accumulation mode aerosol particles with back trajectories indicative of marine origin were examined using a volatilization and humidification tandem differential mobility analyzer (VHTDMA) to reveal the volatilization temperatures of the various component species. The diameter hygroscopic growth factors of the residue particles were continually examined throughout the volatilization process. In each of the three modes the dominant particle type appeared to be composed of the same four physicochemically distinct species though in different ratios. These species exhibited volatility and hygroscopic behavior consistent with combinations of a volatile organic species, sulfuric acid, ammonium sulfate or bisulfate, iodine oxide, and an insoluble nonvolatile residue. The Aitken and accumulation mode aerosols contain large fractions of the insoluble, volatile, organic-like material, and the volatilization of this species results in a distinct increase in the water volume uptake of the particles. Of the four distinct species, only the sulfuric acid-like species constituted an increasing volume fraction with decreasing particle size. This finding indicates that nucleation mode particles constitute an acidic seed and as such would undergo acid-catalyzed secondary organic aerosol growth at a faster rate. The lack of a nonvolatile hygroscopic residue consistent with sea salt in these particles implies that the aerosolization of seawater is not the dominant production mechanism for these submicrometer coastal marine aerosols.

  13. PRENATAL HYPOXIA IN DIFFERENT PERIODS OF EMBRYOGENESIS DIFFERENTIALLY AFFECTS CELL MIGRATION, NEURONAL PLASTICITY AND RAT BEHAVIOR IN POSTNATAL ONTOGENESIS

    Directory of Open Access Journals (Sweden)

    Dmitrii S Vasilev

    2016-03-01

    Full Text Available Long-term effects of prenatal hypoxia on embryonic days E14 or E18 on the number, type and localization of cortical neurons, density of labile synaptopodin-positive dendritic spines and parietal cortex-dependent behavioral tasks were examined in the postnatal ontogenesis of rats. An injection of 5’ethynyl-2’deoxyuridine to pregnant rats was used to label neurons generated on E14 or E18 in the fetuses. In control rat pups a majority of cells labeled on E14 were localized in the lower cortical layers V-VI while the cells labeled on E18 were mainly found in the superficial cortical layers II-III. It was shown that hypoxia both on E14 and E18 results in disruption of neuroblast generation and migration but affects different cell populations. In rat pups subjected to hypoxia on E14, the total number of labeled cells in the parietal cortex was decreased while the number of labeled neurons scattered within the superficial cortical layers was increased. In rat pups subjected to hypoxia on E18, the total number of labeled cells in the parietal cortex was also decreased but the number of scattered labeled neurons was higher in the lower cortical layers. It can be suggested that prenatal hypoxia both on E14 and E18 causes a disruption in neuroblast migration but with a different outcome. Only in rats subjected to hypoxia on E14 did we observe a reduction in the total number of pyramidal cortical neurons and the density of labile synaptopodin-positive dendritic spines in the molecular cortical layer during the first month after birth which affected development of the cortical functions. As a result, rats subjected to hypoxia on E14, but not on E18, had impaired development of the whisker-placing reaction and reduced ability to learn reaching by a forepaw. The data obtained suggest that hypoxia on E14 in the period of generation of the cells, which later differentiate into the pyramidal cortical neurons of the V-VI layers and form cortical minicolumns

  14. EVOLUTION OF AS—CAST MICROSTRUCTURES OF 356 ALUMINIUM ALLOY CAST BY LIQUIDUS CASTING

    Institute of Scientific and Technical Information of China (English)

    J.Dong; G.M.Lu; 等

    2003-01-01

    A new method (liquidus casting)was used for 356 Al alloy semi-solid slurry mak-ing.The structures of 356 Al alloy cast by a fe mould and semi-continuous casting machine at different temperatures were inves tigated.How the globular grains form was qlso discussed.The results show that either being cast by single Fe mould or semi-continuous machine,the microstructures are not conventional dendrites but fine and net-globular grains.The average grain size is smaller than 30μm and suitable enough for thixoforming,meanwhile it can improve the mechanical properties of fol-lowing products.Under the suitable casting velocity and cooling intensity,most of global grains prolong their global browth and collide with each other before dendritic growth because of the large amount of the nucleation sites.

  15. Materials for Advanced Ultrasupercritical Steam Turbines Task 4: Cast Superalloy Development

    Energy Technology Data Exchange (ETDEWEB)

    Thangirala, Mani

    2015-09-30

    The Steam Turbine critical stationary structural components are high integrity Large Shell and Valve Casing heavy section Castings, containing high temperature steam under high pressures. Hence to support the development of advanced materials technology for use in an AUSC steam turbine capable of operating with steam conditions of 760°C (1400°F) and 35 Mpa (5000 psia), Casting alloy selection and evaluation of mechanical, metallurgical properties and castability with robust manufacturing methods are mandated. Alloy down select from Phase 1 based on producability criteria and creep rupture properties tested by NETL-Albany and ORNL directed the consortium to investigate cast properties of Haynes 282 and Haynes 263. The goals of Task 4 in Phase 2 are to understand a broader range of mechanical properties, the impact of manufacturing variables on those properties. Scale up the size of heats to production levels to facilitate the understanding of the impact of heat and component weight, on metallurgical and mechanical behavior. GE Power & Water Materials and Processes Engineering for the Phase 2, Task 4.0 Castings work, systematically designed and executed casting material property evaluation, multiple test programs. Starting from 15 lbs. cylinder castings to world’s first 17,000 lbs. poured weight, heavy section large steam turbine partial valve Haynes 282 super alloy casting. This has demonstrated scalability of the material for steam Turbine applications. Activities under Task 4.0, Investigated and characterized various mechanical properties of Cast Haynes 282 and Cast Nimonic 263. The development stages involved were: 1) Small Cast Evaluation: 4 inch diam. Haynes 282 and Nimonic 263 Cylinders. This provided effects of liquidus super heat range and first baseline mechanical data on cast versions of conventional vacuum re-melted and forged Ni based super alloys. 2) Step block castings of 300 lbs. and 600 lbs. Haynes 282 from 2 foundry heats were evaluated which

  16. A Comparative Study on Wear Properties of As Cast, Cast Aged and Forge Aged A356 Alloy with Addition of Grain Refiner and/or Modifier

    Directory of Open Access Journals (Sweden)

    D.G. Mallapur

    2015-03-01

    Full Text Available In the present work, a comparative wear behavior study of three categories of materials viz, as cast, cast aged (casting followed by T6 and forge aged (forging followed by T6 has been investigated. Neither melt treatment nor solid state processing (like aging and forging seems to be altering the wear behavior of the materials drastically. Cast aged A356 materials exhibit higher wear resistance compared to as cast and forge aged A356 materials. Further, it was observed that cast aged samples register lower coefficient of friction compared to other samples. It is also noted that the difference in wear behavior is revealed only at conditions of higher load, higher speed and longer sliding distance of testing. At lower regimes the difference is marginal. Among cast aged samples, ones treated with combined addition exhibit better wear resistance compared to other materials. Samples treated with combined addition register lowest coefficient of friction followed by samples treated with Sr, those with B, those with Ti and untreated ones. Abrasive wear mechanism is found to be operative in the regime of higher loading and higher velocity of sliding. Adhesive wear mechanism seems to be dominating the wear process at the lower regime of load and velocity of sliding.

  17. Comparison of marginal accuracy of castings fabricated by conventional casting technique and accelerated casting technique: An in vitro study

    Directory of Open Access Journals (Sweden)

    S Srikanth Reddy

    2013-01-01

    Full Text Available Background: Conventional casting technique is time consuming when compared to accelerated casting technique. In this study, marginal accuracy of castings fabricated using accelerated and conventional casting technique was compared. Materials and Methods: 20 wax patterns were fabricated and the marginal discrepancy between the die and patterns were measured using Optical stereomicroscope. Ten wax patterns were used for Conventional casting and the rest for Accelerated casting. A Nickel-Chromium alloy was used for the casting. The castings were measured for marginal discrepancies and compared. Results: Castings fabricated using Conventional casting technique showed less vertical marginal discrepancy than the castings fabricated by Accelerated casting technique. The values were statistically highly significant. Conclusion: Conventional casting technique produced better marginal accuracy when compared to Accelerated casting. The vertical marginal discrepancy produced by the Accelerated casting technique was well within the maximum clinical tolerance limits. Clinical Implication: Accelerated casting technique can be used to save lab time to fabricate clinical crowns with acceptable vertical marginal discrepancy.

  18. NUMERICAL MODELING OF HARDENING OF UNINTERRUPTEDLY-CASTED BRONZE CASTING

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2009-01-01

    Full Text Available The three-dimensional numerical model for calculation of thermal fields during solidification of continuously casted bronze casting is developed. Coefficients of heat transfer on borders of calculation areas on the basis of the solution of inverse heat transfer conduction problem are determined. The analysis of thermal fields, depending on loop variables of drawing and the sizes of not cooled zone of crystallizer is curried out.

  19. Modelling of flow phenomena during DC casting

    NARCIS (Netherlands)

    Zuidema, J.

    2005-01-01

    Modelling of Flow Phenomena during DC Casting Jan Zuidema The production of aluminium ingots, by semi-continuous casting, is a complex process. DC Casting stands for direct chill casting. During this process liquid aluminium transforms to solid aluminium while cooling down. This is not an instanta

  20. Drosophila insulin-producing cells are differentially modulated by serotonin and octopamine receptors and affect social behavior.

    Directory of Open Access Journals (Sweden)

    Jiangnan Luo

    Full Text Available A set of 14 insulin-producing cells (IPCs in the Drosophila brain produces three insulin-like peptides (DILP2, 3 and 5. Activity in IPCs and release of DILPs is nutrient dependent and controlled by multiple factors such as fat body-derived proteins, neurotransmitters, and neuropeptides. Two monoamine receptors, the octopamine receptor OAMB and the serotonin receptor 5-HT1A, are expressed by the IPCs. These receptors may act antagonistically on adenylate cyclase. Here we investigate the action of the two receptors on activity in and output from the IPCs. Knockdown of OAMB by targeted RNAi led to elevated Dilp3 transcript levels in the brain, whereas 5-HT1A knockdown resulted in increases of Dilp2 and 5. OAMB-RNAi in IPCs leads to extended survival of starved flies and increased food intake, whereas 5-HT1A-RNAi produces the opposite phenotypes. However, knockdown of either OAMB or 5-HT1A in IPCs both lead to increased resistance to oxidative stress. In assays of carbohydrate levels we found that 5-HT1A knockdown in IPCs resulted in elevated hemolymph glucose, body glycogen and body trehalose levels, while no effects were seen after OAMB knockdown. We also found that manipulations of the two receptors in IPCs affected male aggressive behavior in different ways and 5-HT1A-RNAi reduced courtship latency. Our observations suggest that activation of 5-HT1A and OAMB signaling in IPCs generates differential effects on Dilp transcription, fly physiology, metabolism and social interactions. However the findings do not support an antagonistic action of the two monoamines and their receptors in this particular system.

  1. Application of the gel casting process in iron powder metallurgy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effects of various gel casting process parameters such as the dispersant and solid loading on the rheology of Fe slurries, molding, and sintering behaviors were studied. The relationship between solid loading and viscidity in the process of iron base powder metallurgy was researched to obtain better microstructure and properties. The results showed that the viscosity of Fe slurries is obviously reduced with the increase of the dispersant. The suitable parameters are as follows: the solid loading is 61% and sintering temperature is 1180℃. Iron parts with relatively high density and better properties were obtained by the gel casting process.

  2. Casting Using A Polystyrene Pattern

    Science.gov (United States)

    Vasquez, Peter; Guenther, Bengamin; Vranas, Thomas; Veneris, Peter; Joyner, Michael

    1993-01-01

    New technique for making metal aircraft models saves significant amount of time and effort in comparison with conventional lost-wax method. Produces inexpensive, effective wind-tunnel models. Metal wind-tunnel model cast by use of polystyrene pattern.

  3. The CAST Time Projection Chamber

    CERN Document Server

    Autiero, D; Cébrian, S; Carmona, J M; Chesi, Enrico Guido; Davenport, M; Delattre, M; Di Lella, L; Formenti, F; Gomez, H; Hasinoff, M; Irastorza, I G; Lakic, B; Luzón, G; Morales, J; Musa, L; Ortiz, A; Placci, A; Rodríguez, A; Ruz, J; Villar, J A; Zioutas, K

    2007-01-01

    One of the three X-ray detectors of the CAST experiment searching for solar axions is a Time Projection Chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure. Its design has been optimized to provide high sensitivity to the detection of the low intensity X-ray signal expected in the CAST experiment. A low hardware threshold of 0.8 keV is safely set during normal data taking periods, and the overall efficiency for the detection of photons coming from conversion of solar axions is 62 %. Shielding has been installed around the detector, lowering the background level to 4.10 x 10^-5 counts/cm^2/s/keV between 1 and 10 keV. During phase I of the CAST experiment the TPC has provided robust and stable operation, thus contributing with a competitive result to the overall CAST limit on axion-photon coupling and mass.

  4. Some Theoretical Considerations on Caste

    Directory of Open Access Journals (Sweden)

    Madhusudan Subedi

    2014-05-01

    Full Text Available Caste as a system of social stratification was an encompassing system in the past. There was reciprocal system of exchange goods and services. With time, occupation and mode of generation of livelihood of various caste groups changed, and the traditional form of jajmani system fizzled out. This paper provides an account of changing perspectives of caste relations in social science writing and political discourse. The discourse of caste has been shifted from ritual hierarchy and social discrimination to an instrument to mobilize people for economic and political gain. DOI: http://dx.doi.org/10.3126/dsaj.v7i0.10437 Dhaulagiri Journal of Sociology and Anthropology Vol. 7, 2013; 51-86

  5. Anisotropic shrinkage characteristics of tape cast alumina

    Science.gov (United States)

    Patwardhan, Jaideep Suresh

    Dimensional control during sintering is a major issue in ceramics processing to avoid high post-sintering costs associated with machining of the fired ceramic part to desired tolerances and dimensions. Ceramic forming processes such as tape casting, injection molding, and extrusion involve shear of anisotropic particles resulting in preferential alignment of the particles in the green body. This preferential alignment causes directionality in mechanical, electrical, optical, and magnetic properties and most importantly warpage or distortion during sintering. A large effort has been devoted to synthesizing ceramic green bodies with minimal density gradients and uniform packing and modeling the sintering behavior evolution but little effort has been devoted to characterizing orientation of particles and the effect of preferential alignment on sintering shrinkage anisotropy. A systematic study was initiated to study the effect of processing variables such as shear rate, solids loading, temperature, and binder content on aqueous tape cast alumina. Three different alumina systems: A16-SG, Baikowski RC-UFX DBM and RC-LS DBM were investigated. Aqueous tapes of high solids loading alumina (56 vol. %) were tape cast at various speeds and thicknesses and assuming plane Couette flow a shear rate regime of 21--270 s-1 was investigated. Higher shear rates and high solids loading resulted in higher in-plane anisotropy whereas the anisotropy in the thickness direction was higher for low solids loading systems. The anisotropy was found to be fairly constant above a certain critical shear rate (˜100 s-1) irrespective of the temperature and the solids loading and this correlated with the viscosity-shear rate relationship of the cast slips. The higher shrinkage anisotropy in the thickness direction for the low solids loading systems (35 and 45 vol. %) was attributed to the higher amount of organics in the slip required to sustain the suitable viscosity for tape casting and

  6. Electrochemical characterization of cast titanium alloys.

    Science.gov (United States)

    Cai, Zhuo; Shafer, Ty; Watanabe, Ikuya; Nunn, Martha E; Okabe, Toru

    2003-01-01

    A reaction layer forms on cast titanium alloy surfaces due to the reaction of the molten metal with the investment. This surface layer may affect the corrosion of the alloy in the oral environment. The objective of this study was to characterize the in vitro corrosion behavior of cast titanium alloys. ASTM Grade 2 CP titanium, Ti-6Al-4V, Ti-6Al-7Nb and Ti-13Nb-13Zr alloys were cast into a MgO-based investment. Experiments were performed on castings (N=4) with three surface conditions: (A) as-cast surface after sandblasting, (B) polished surface after removal of the reaction layer, and (C) sandblasted surface after removal of the reaction layer. Open-circuit potential (OCP) measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air+10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was subsequently conducted in the same medium deaerated with N(2)+10% CO(2) gas 2 h before and during the experiment. Polarization resistance (R(P)) and corrosion rate (I(CORR)) were calculated. Numerical results were subjected to nonparametric statistical analysis at alpha=0.05. The OCP stabilized for all the specimens after 6 x 10(4)s. Apparent differences in anodic polarization were observed among the different surfaces for all the metals. A passivation region followed by breakdown and repassivation were seen on specimens with surfaces A and C. An extensive passive region was observed on all the metals with surface B. The Kruskal-Wallis test showed no significant differences in OCP, R(p), I(CORR) or break down potential for each of the three surfaces among all the metals. The Mann-Whitney test showed significantly lower R(P) and higher I(CORR) values for surface C compared to the other surfaces. Results indicate that the surface condition has more effect on corrosion of these alloys than the surface reaction layer. Within the oxidation potential range of the oral cavity, all the metal

  7. Behaviorism

    Science.gov (United States)

    Moore, J.

    2011-01-01

    Early forms of psychology assumed that mental life was the appropriate subject matter for psychology, and introspection was an appropriate method to engage that subject matter. In 1913, John B. Watson proposed an alternative: classical S-R behaviorism. According to Watson, behavior was a subject matter in its own right, to be studied by the…

  8. Inoculation of chromium white cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-01-01

    Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  9. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    @@ Vermicular graphite cast iron(VG iron for short in the following sections)is a type of cast iron in which the graphite is intermediate in shape between flake and spheroidal.Compared with the normal flake graphite in grey iron, the graphite in VG iron is shorter and thicker and shows a curved, more rounded shape.Because its outer contour is exactly like a worm, hence it is called vermicular graphite.

  10. Agile Manufacturing Development of Castings

    Science.gov (United States)

    2007-11-02

    responsible for con- verting the available 2D CATIA casting design into a 3D Pro/Engineering geometric model of the casting, for use by Clinkenbeard...changes to the draw- ings. MWM. As the part designer, MWM reviewed and evalu- ated proposed changes to the design. MWM also updated the CATIA ...creation of solid models of the cores and molds, using IGES translations of the CATIA files secured from MWM through GE Transportation Sys- tems. Due

  11. Comparing the effects of differential reinforcement of other behavior and response-cost contingencies on tics in youth with Tourette syndrome.

    Science.gov (United States)

    Capriotti, Matthew R; Brandt, Bryan C; Ricketts, Emily J; Espil, Flint M; Woods, Douglas W

    2012-01-01

    Tics are rapid, repetitive, stereotyped movements or vocalizations that arise from neurobiological dysfunction and are influenced by environmental factors. Although persons with tic disorders often experience aversive social reactions in response to tics, little is known about the behavioral effects of such consequences. Along several dimensions, the present study compared the effects of two treatments on tics: response cost (RC) and differential reinforcement of other behavior (DRO). Four children with Tourette syndrome were exposed to free-to-tic baseline, DRO, RC, and quasibaseline rebound evaluation conditions using an alternating treatments design. Both DRO and RC produced substantial decreases in tics from baseline levels. No differential effects of DRO and RC contingencies were seen on self-reported stress or in the strength of the reflexive motivating operation (i.e., premonitory urge) believed to trigger tics, and neither condition produced tic-rebound effects. Implications of these findings and directions for future research are discussed.

  12. Microstructural evolution and mechanical properties of as-cast and T6-treated AA2195 DC cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hekmat-Ardakan, A. [Universite de Sherbrook, Sherbrook, QC, Canada J1K 2R1 (Canada); Elgallad, E.M. [Universite du Quebec a Chicoutimi, Chicoutimi, QC, Canada G7H 2B1 (Canada); Ajersch, F. [Ecole Polytechnique de Montreal, Montreal, QC, Canada H3T 1J4 (Canada); Chen, X.-G., E-mail: xgrant_chen@uqac.ca [Universite du Quebec a Chicoutimi, Chicoutimi, QC, Canada G7H 2B1 (Canada)

    2012-12-15

    The use of direct chill (DC) cast ingot plates of AA2195 alloys has been recently extended for large mold applications in the plastics and automotive industries. The microstructural evolution of the as-cast AA2195 alloy was investigated using the Factsage thermodynamic software under both equilibrium and non-equilibrium conditions, and was compared with the results from differential scanning calorimetry (DSC) analysis and microstructural observations. The as-cast microstructure exhibited the presence of Al{sub 2}CuMg, Al{sub 2}Cu and Al{sub 2}CuLi intermetallic phases formed at the aluminum dendrite boundaries, which can be completely dissolved in the {alpha}-Al matrix during the solution treatment. A significant improvement in the mechanical properties of the AA2195 cast alloy after the T6 heat treatment is attributed to the formation of nano-scale {theta} Prime (Al{sub 2}Cu) and T1 (Al{sub 2}CuLi) precipitates. However, the non-uniform distribution of T1 precipitates together with the large size and low density indicate that the role of {theta} Prime precipitates in strengthening the AA2195 cast alloy is more dominant than that of the T1 precipitates, in contrast with the strengthening mechanism of the pre-deformed AA2195-T8 rolled products.

  13. Moldless casting by laser

    Science.gov (United States)

    McLean, Marc A.; Shannon, G. J.; Steen, William M.

    1997-09-01

    The principle of laser cladding involves the use of high power carbon-dioxide lasers and powder deposition technology to provide wear and corrosion resistant surface coatings to engineering components. By injecting metal powder into a laser generated melt pool on a moving substrate a solidified metal track can be produced. Deposition of successive tracks produces a multi-layer build. Laser direct casting (LDC) utilizes a coaxial nozzle enabling consistent omnidirectional deposition to produce 3D components from a selection of metal powders. The influence of the principal process parameters over the process features namely, powder catchment efficiency, beam shape and build rates are presented with several successfully generated 3D components. Nickel, stainless steel and satellite powders were deposited at laser powders of 0.4 to 1.4 kW and speeds of 500 to 1000 mm/min achieving build rates of 3 to 9 mm3/s. Fully dense metallurgical structures have been produced with no cracking or porosity and powder catchment efficiencies up to 85% have been achieved.

  14. Light metal compound casting

    Institute of Scientific and Technical Information of China (English)

    Konrad; J.; M.; PAPIS; Joerg; F.; LOEFFLER; Peter; J.; UGGOWITZER

    2009-01-01

    ‘Compound casting’simplifies joining processes by directly casting a metallic melt onto a solid metal substrate. A continuously metallurgic transition is very important for industrial applications, such as joint structures of spaceframe constructions in transport industry. In this project, ‘compound casting’ of light metals is investigated, aiming at weight-saving. The substrate used is a wrought aluminium alloy of type AA5xxx, containing magnesium as main alloying element. The melts are aluminium alloys, containing various alloying elements (Cu, Si, Zn), and magnesium. By replacing the natural oxygen layer with a zinc layer, the inherent wetting difficulties were avoided, and compounds with flawless interfaces were successfully produced (no contraction defects, cracks or oxides). Electron microscopy and EDX investigations as well as optical micrographs of the interfacial areas revealed their continu- ously metallic constitution. Diffusion of alloying elements leads to heat-treatable microstructures in the vicinity of the joining interfaces in Al-Al couples. This permits significant variability of mechanical properties. Without significantly cutting down on wettability, the formation of low-melting intermetallic phases (Al3Mg2 and Al12Mg17 IMPs) at the interface of Al-Mg couples was avoided by applying a protective coating to the substrate.

  15. Application of particle method to the casting process simulation

    Science.gov (United States)

    Hirata, N.; Zulaida, Y. M.; Anzai, K.

    2012-07-01

    Casting processes involve many significant phenomena such as fluid flow, solidification, and deformation, and it is known that casting defects are strongly influenced by the phenomena. However the phenomena complexly interacts each other and it is difficult to observe them directly because the temperature of the melt and other apparatus components are quite high, and they are generally opaque; therefore, a computer simulation is expected to serve a lot of benefits to consider what happens in the processes. Recently, a particle method, which is one of fully Lagrangian methods, has attracted considerable attention. The particle methods based on Lagrangian methods involving no calculation lattice have been developed rapidly because of their applicability to multi-physics problems. In this study, we combined the fluid flow, heat transfer and solidification simulation programs, and tried to simulate various casting processes such as continuous casting, centrifugal casting and ingot making. As a result of continuous casting simulation, the powder flow could be calculated as well as the melt flow, and the subsequent shape of interface between the melt and the powder was calculated. In the centrifugal casting simulation, the mold was smoothly modeled along the shape of the real mold, and the fluid flow and the rotating mold are simulated directly. As a result, the flow of the melt dragged by the rotating mold was calculated well. The eccentric rotation and the influence of Coriolis force were also reproduced directly and naturally. For ingot making simulation, a shrinkage formation behavior was calculated and the shape of the shrinkage agreed well with the experimental result.

  16. Copper base materials prepared by gel-casting process

    Institute of Scientific and Technical Information of China (English)

    LIU Weihua; JIA Chengchang; SHI Yantao; HAN Yuepeng

    2008-01-01

    Gel-casting process was developed as a new molding process in the field of copper base powder metallurgy to manufacture metal parts with excellent performance and complex shapes.Through changing the parameters of gel-casting process,such as dispersant and solid loading,the corresponding effects on the rheology of Cu slurries,molding and sintering behaviors were studied.The results show that the viscosity of Cu slurries was significantly reduced with an increase in dispersant.The most appropriate solid loading was found to be 61% and the sintering temperature was 910℃ in these experiments.After the optimization of parameters of gel-casting process,copper composite parts with relatively high density and better properties were obtained.

  17. EVOLUTION OF AS-CAST MICROSTRUCTURES OF 356 ALUMINIUM ALLOY CAST BY LIQUIDUS CASTING

    Institute of Scientific and Technical Information of China (English)

    J. Dong; G.M. Lu; J.Z. Cui; Z.H. Zhao

    2003-01-01

    A new method (liquidus casting) was used for 356 Al alloy semi-solid slurry mak-ing. The structures of 356 Al alloy cast by a Fe mould and semi-continuous castingmachine at different temperatures were investigated. How the globular grains formwas also discussed. The results show that either being cast by single Fe mould orsemi-continuous machine, the microstructures are not conventional dendrites but fineand net-globular grains. The average grain size is smaller than 30μm and suitableenough for thixoforming, meanwhile it can improve the mechanical properties of fol-lowing products. Under the suitable casting velocity and cooling intensity, most ofglobal grains prolong their global growth and collide with each other before dendriticgrowth because of the large amount of the nucleation sites.

  18. Untouchable castes of Uttar Pradesh

    Directory of Open Access Journals (Sweden)

    Kharinin Artem Igorevich

    2015-04-01

    Full Text Available The Untouchable Castes of Uttar Pradesh are examined in this article. This region is one of the most populated in India. Also it is one of the most social mixed-composed in whole State. That’s why main conclusions which were made on this material can be extrapolated to all social space of country. The authors choose four ethno-caste groups, which represent the majority in untouchables and the three smallest in jaties. Their positions in regional hierarchy and economic specialization are analyzed in detail. There are a lot of information about their number, social structure, literacy rating, endogamy, day-to-day practices, customs and other features. Special accents were pointed on mind orientation of their elites toward integration in modern society or, conversely, toward the conservation of traditional forms of existence. The issues of origin and social evolution of untouchable castes of Uttar Pradesh are examined. There is assessment of castes’ sanskritization or other forms of social selfdevelopment. The quality of “scheduled” castes social environment is analyzed. As a marks of its positiveness the data about discrimination untouchables from other social groups and degree of political representativeness of “scheduled” castes, accessibility of education and labour were chosen. The conclusions were made about development degree of some castes. The factors that play role in positive changes in contemporary conditions were determined. The authors put forward their own hypothesis of future development of untouchable castes in Uttar Pradesh. Empiric base of this article was established on sources that have Indian origin and historical and social research of outstanding western indologies.

  19. Development of vacuum die-casting process

    Institute of Scientific and Technical Information of China (English)

    Masashi Uchida

    2009-01-01

    The vacuum die-casting process, started 25 years ago in Japan, has been widely applied. This technology contributes very much to improvement of castings quality. The main factor causing the defects of die castings is the trapped air in the mold cavity, while the key technology of vacuum die-casting process is to avoid the trapped air effectively by evacuating the cavity before casting. At the same time, due to the shot speed and the casting pressure reduced in half, the service life of the die is prolonged and the productivity is enhanced, as well. Vacuum die-casting process is of great significance in improving the die castings quality and making up the shortcomings of super-high-speed shot casting.

  20. Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

    2005-09-30

    Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the

  1. Final Report, Volume 1, Metallurgical Evaluation of Cast Duplex Stainless Steels and their Weldments

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Songqing; Lundin, Carl, W.; Batten, Greg, W.

    2005-09-30

    Duplex stainless steels (DSS) are being specified for chloride containing environments due to their enhanced pitting and stress corrosion cracking resistance. They exhibit improved corrosion performance over the austenitic stainless steels. Duplex stainless steels also offer improved strength properties and are available in various wrought and cast forms. Selected grades of duplex stainless steel castings and their welds, in comparison with their wrought counterparts, were evaluated, regarding corrosion performance and mechanical properties and weldability. Multiple heats of cast duplex stainless steel were evaluated in the as-cast, solution annealed (SA) static cast and SA centrifugal cast conditions, while their wrought counterparts were characterized in the SA condition and in the form of as-rolled plate. Welding, including extensive assessment of autogenous welds and a preliminary study of composite welds (shielded metal arc weld (SMAW)), was performed. The evaluations included critical pitting temperature (CPT) testing, intergranular corrosion (IGC) testing, ASTM A923 (Methods A, B and C), Charpy impact testing, weldability testing (ASTM A494), ferrite measurement and microstructural evaluations. In the study, the corrosion performances of DSS castings were characterized and assessed, including the wrought counterparts for comparison. The evaluation filled the pore of lack of data for cast duplex stainless steels compared to wrought materials. A database of the pitting corrosion and IGC behavior of cast and wrought materials was generated for a greater depth of understanding for the behavior of cast duplex stainless steel. In addition, improved evaluation methods for DSS castings were developed according to ASTM A923, A262, G48 and A494. The study revealed that when properly heat treated according to the specification, (1) DSS castings have equal or better pitting and intergranular corrosion resistance than their wrought counterparts; (2) Welding reduces the

  2. Heat Transfer between Casting and Dieduring High Pressure Die Casting Process of AM50 Alloy-Modeling and Experimental Results

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A method based on die casting experiments and mathematic modeling is presented for the determination of the heat flow density (HFD) and interfacial heat transfer coefficient (IHTC) during the high pressure die casting (HPDC) process. Experiments were carried out using step shape casting and a commercial magnesium alloy, AM50. Temperature profiles were measured and recorded using thermocouples embedded inside the die.Based on these temperature readings, the HFD and IHTC were successfully determined and the calculation results show that the HFD and IHTC at the metal-die interface increases sharply right after the fast phase injection process until approaching their maximum values, after which their values decrease to a much lower level until the dies are opened. Different patterns of heat transler behavior were found between the die and the castingat different thicknesses. The thinner the casting was, the more quickly the HFD and IHTC reached their steady states. Also, the values for both the HFD and IHTC values were different between die and casting at different thicknesses.

  3. As-Cast Acicular Ductile Aluminum Cast Iron

    Institute of Scientific and Technical Information of China (English)

    S M Mostafavi Kashani; S M A Boutorabi

    2009-01-01

    The effects of nickel (2.2%)and molybdenum (0.6%)additions on the kinetics, microstructure, and me-chanical properties of ductile aluminum cast iron were studied under the as-cast and tempered conditions. Test bars machined from cast to size samples were used for mechanical and metallurgical studies. The results showed that adding nickel and molybdenum to the base iron produced an upper bainitic structure, resulting in an increase in strength and hardness. The same trend was shown when the test bars were tempered at 300 ℃ in the range of 300℃ to 400 ℃. The elongation increased with increasing the temperature from 300 ℃ to 400 ℃. The carbon content of the retained austenite also increased with increasing the temperature. The results also showed that the kinetics, mi-crostructure, and mechanical properties of this iron were similar to those of Ni-Mo alloyed silicon ductile iron.

  4. Psychological and behavioral intervention improves the quality of life and mental health of patients suffering from differentiated thyroid cancer treated with postoperative radioactive iodine-131

    Directory of Open Access Journals (Sweden)

    Wu HX

    2016-05-01

    Full Text Available Hong-Xia Wu,1,* Hua Zhong,2,3,* Yue-Dong Xu,1 Cui-Ping Xu,4 Ying Zhang,5 Wei Zhang1 1Department of Endocrinology, Shandong Provincial Qianfoshan Hospital, Shandong University, 2Department of Oncology, Shandong University of Traditional Chinese Medicine, 3Department of Traditional Chinese Medicine, Shandong Provincial Qianfoshan Hospital, Shandong University, 4Department of Nursing, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong, 5Department of Nursing, Tianjin Chest Hospital, Tianjing, People’s Republic of China *These authors contributed equally to this work Background: We examined the effects of psychological and behavioral intervention on health-related quality of life and mental health among patients suffering from differentiated thyroid cancer (DTC treated with postoperative radioactive iodine-131 (RAI.Methods: Sixty patients with DTC, undergoing RAI, were randomly assigned to receive either conventional nursing (n=30 or a 1-year psychological and behavioral intervention based on conventional nursing (n=30. Health-related quality of life and mental health issues, depression, and anxiety were measured using the Quality of Life Core Questionnaire, Self-rating Depression Scale, and Self-rating Anxiety Score, respectively.Results: After RAI treatment, patients in both groups showed improved functional capacities (ie, physical, role, cognitive, emotional, and social and global quality of life, along with reduced depression and anxiety (P<0.05. At 1-year follow-up, compared with patients in the routine nursing group, those in the psychological and behavioral intervention group demonstrated greater improvements in functional capacities, global quality of life, and depression and anxiety symptoms (P<0.05.Conclusion: Psychological and behavioral interventions for patients with DTC undergoing RAI facilitated positive outcomes, suggesting that nursing care models that include psychological and behavioral interventions

  5. Characterization of Acetone-Solution Casting Film of PMMA

    Institute of Scientific and Technical Information of China (English)

    Xue Feng; Fu Weiwen; Cheng Rongshi

    2006-01-01

    Acetone solution-casting films of poly(methylmethacrylate)were analyzed by differential scanning calorimetry and pyrolysis gas chromatography-mass spectroscopy under natural evaporation and ultrasonic vibration,respectively.Analytical results indicate that both the condensed structure of the polymer and the residue solvent in the films vary in different film-forming conditions and that the residuesolvated acetone in films prepared under natural evaporation is 12 times greater than that under ultrasonic vibration.

  6. Application of Numerical Simulation Technique to Casting Process of Valve Block

    Institute of Scientific and Technical Information of China (English)

    MI Guo-fa; LIU Xiang-yu; WANG Kuang-fei; FU Heng-zhi

    2009-01-01

    The numerical simulation technique was applied to the casting process of a valve-type part. The mold-filling and solidification stages of the casting were numerically analyzed. The filling behavior, solidification sequence,and thermal stress distribution were reproduced and the possible defects, such as cold shut and shrinkage, were predicted. Based on the simulation result, the double-gating system was replaced by a single-gating system. Meanwhile,the chills were used to regulate the solidification sequence of casting. To eliminate the cracks in the casting, the sand core was converted into a canulate one. By modifying the original process, the defects were eliminated and the casting with good quality was obtained.

  7. Research progress on squeeze casting in China

    Institute of Scientific and Technical Information of China (English)

    Li Yuanyuan; Zhang Weiwen; Zhao Haidong; You Dongdong; Zhang Datong; Shao Ming; Zhang Wen

    2014-01-01

    Squeeze casting is a technology with short route, high efficiency and precise forming, possessing features of casting and plastic processing. It is widely used to produce high performance metallic structural parts. As energy conservation and environmental protection concerns have risen, lightweight and high performance metal parts are urgently needed, which accelerated the development of squeeze casting technology over the past two decades in China. In this paper, research progress on squeeze casting aloys, typical parts manufacturing and development of squeeze casting equipment in China are introduced. The future trend and development priorities of squeeze casting are discussed.

  8. Effect of heat treatment on the wear and corrosion behaviors of a gray cast iron coated with a COLMONOY 88 alloy deposited by high velocity oxygen fuel (HVOF thermal spray

    Directory of Open Access Journals (Sweden)

    A. Öz

    2013-07-01

    Full Text Available The present work has been conducted in order to determine the influence of heat treatment on the wear and corrosion behaviours of a gray cast iron substrate coated with a Ni base coating deposited by HVOF thermal spray. The wear resistance of the coatings was obtained using a reciprocating wear tester by rubbing a 10 mm diameter steel ball on the coatings at normal atmospheric conditions. Corrosion tests were performed using potentiodynamic polarization measurements in a 3,5 % NaCl solution. It was observed that the corrosion and wear resistance of the coatings increased along with the reduction of porosity and roughness by the heat treatment.

  9. Fractomechanical Properties of As-Cast and Austempered SG Cast Iron Between -40 °C and +20 °C

    Directory of Open Access Journals (Sweden)

    V.E. Fierro

    2002-06-01

    Full Text Available The spheroidal graphite (SG cast iron fractomechanical response varies with the test temperature and with the microstructure parameters. In the present paper, we analyze this variation performing fractomechanical tests in a temperature range from -40°C to +20°C, doing also Charpy and tensile tests for material characterization. The tests were carried out on as-cast samples and heat treated samples to obtain an ADI grade 1. In both cases, we studied samples taken from two well differentiated "Y" block sizes. The results obtained show that, for the chemical composition analyzed, both castings have a fractomechanical response decrease as the temperature diminishes. Besides, the block size enlargement produce a deterioration of the mechanical properties (the fracture toughness, mainly, for both castings.

  10. L-type calcium channels and calcium/calmodulin-dependent kinase II differentially mediate behaviors associated with nicotine withdrawal in mice.

    Science.gov (United States)

    Jackson, K J; Damaj, M I

    2009-07-01

    Smoking is a widespread health problem. Because the nicotine withdrawal syndrome is a major contributor to continued smoking and relapse, it is important to understand the molecular and behavioral mechanisms of nicotine withdrawal to generate more effective smoking cessation therapies. Studies suggest a role for calcium-dependent mechanisms, such as L-type calcium channels and calcium/calmodulin-dependent protein kinase II (CaMKII), in the effects of nicotine dependence; however, the role of these mechanisms in nicotine-mediated behaviors is unclear. Thus, the goal of this study was to elucidate the role of L-type calcium channels and CaMKII in nicotine withdrawal behaviors. Using both pharmacological and genetic methods, our results show that L-type calcium channels are involved in physical, but not affective, nicotine withdrawal behaviors. Although our data do provide evidence of a role for CaMKII in nicotine withdrawal behaviors, our pharmacological and genetic assessments yielded different results concerning the specific role of the kinase. Pharmacological data suggest that CaMKII is involved in somatic signs and affective nicotine withdrawal, and activity level is decreased after nicotine withdrawal, whereas the genetic assessments yielded results suggesting that CaMKII is involved only in the anxiety-related response, yet the kinase activity may be increased after nicotine withdrawal; thus, future studies are necessary to clarify the precise behavioral specifics of the relevance of CaMKII in nicotine withdrawal behaviors. Overall, our data show that L-type calcium channels and CaMKII are relevant in nicotine withdrawal and differentially mediate nicotine withdrawal behaviors.

  11. Energy Consumption of Die Casting Operations

    Energy Technology Data Exchange (ETDEWEB)

    Jerald Brevick; clark Mount-Campbell; Carroll Mobley

    2004-03-15

    Molten metal processing is inherently energy intensive and roughly 25% of the cost of die-cast products can be traced to some form of energy consumption [1]. The obvious major energy requirements are for melting and holding molten alloy in preparation for casting. The proper selection and maintenance of melting and holding equipment are clearly important factors in minimizing energy consumption in die-casting operations [2]. In addition to energy consumption, furnace selection also influences metal loss due to oxidation, metal quality, and maintenance requirements. Other important factors influencing energy consumption in a die-casting facility include geographic location, alloy(s) cast, starting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting machine, related equipment (robots, trim presses), and downstream processing (machining, plating, assembly, etc.). Each of these factors also may influence the casting quality and productivity of a die-casting enterprise. In a die-casting enterprise, decisions regarding these issues are made frequently and are based on a large number of factors. Therefore, it is not surprising that energy consumption can vary significantly from one die-casting enterprise to the next, and within a single enterprise as function of time.

  12. CAST Physics Proposal to SPSC

    CERN Document Server

    CAST, Collaboration

    2011-01-01

    The CAST experiment has the potential to search for solar axions (dark matter particle candidates) or other particles with similar coupling. E.g., paraphtons (Hidden Sector), chameleons (dark energy), while considering the possibility whether CAST could be transformed to an antenna for relic axions with rest mass up to 0.1 to 1meV. While axion searches suggest detectors with lower background, paraphoton and chameleon searches require detectors with sub-keV threshold energy and the use of transparent windows in front of the Micromegas detectors, which cover 3 out of the 4 CAST magnet exits. Ongoing theoretical estimates and experimental investigations will define the priorities of the suggested 4 physics items of this proposal for the period 2012-2014.

  13. Violent Behaviors in Drug Addiction: Differential Profiles of Drug-Addicted Patients with and without Violence Problems

    Science.gov (United States)

    Fernandez-Montalvo, Javier; Lopez-Goni, Jose J.; Arteaga, Alfonso

    2012-01-01

    This study explored the prevalence of violent behaviors in patients who are addicted to drugs. A sample of 252 addicted patients (203 male and 49 female) who sought outpatient treatment was assessed. Information on violent behaviors, sociodemographic factors, consumption factors (assessed by the European version of the Addiction Severity Index…

  14. WEAR-RESISTANCE OF CHROMIC CAST IRONS OF EUTECTIC COMPOSITION

    Directory of Open Access Journals (Sweden)

    K. E. Baranovskij

    2009-01-01

    Full Text Available Casting of wear-resistant chrome cast irons in combined molds and iron chills is studied. Application of these ways of casting results in blending of carbides and increasing of hardness of castings.

  15. Investigation of Oxide Bifilms in Investment Cast Superalloy IN100: Part II. Characterization

    Science.gov (United States)

    Kaplan, Max A.; Fuchs, Gerhard E.

    2016-05-01

    Oxide bifilms are a proposed casting inclusion reported to have been observed in vacuum investment cast polycrystalline Ni-based superalloys. Ongoing research seeks to determine if current superalloy casting practices can result in the formation of oxide bifilms, and subsequently if it is possible to observe and characterize this phenomenon. The effect of casting atmosphere, turbulence, filtering, hot isostatic pressing, and heat treatment has been investigated to identify the critical parameters that have been reported to result in bifilm formation in Ni-based superalloy IN100. Scanning Auger microscopy (SAM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM) were utilized to characterize samples from each casting condition. In situ ultrahigh vacuum Auger fractography did not indicate the presence of bifilms on the fracture behavior of IN100 in any processing condition. SAM analysis identified a sulfur-enriched monolayer on the surface of dendritic casting porosity, and identified heterogeneous Ti oxycarbide inclusions in air cast IN100. SEM analysis also indicated the presence of Ti oxycarbide inclusions in air cast IN100, and determined that these inclusion structures consist of fine blocky external M(Ti, Mo)C carbide enveloping an internal core of alumina. HR-TEM analysis indicated that none of the oxycarbide inclusion interfaces exist as discontinuous unbound interfaces, and that the internal alumina core is an ultra-fine polycrystalline structure.

  16. The mechanisms underlying sexual differentiation of behavior and physiology in mammals and birds: relative contributions of sex steroids and sex chromosomes

    Directory of Open Access Journals (Sweden)

    Fumihiko eMaekawa

    2014-08-01

    Full Text Available From a classical viewpoint, sex-specific behavior and physiological functions as well as the brain structures of mammals such as rats and mice, have been thought to be influenced by perinatal sex steroids secreted by the gonads. Sex steroids have also been thought to affect the differentiation of the sex-typical behavior of a few members of the avian order Galliformes, including the Japanese quail and chickens, during their development in ovo. However, recent mammalian studies that focused on the artificial shuffling or knockout of the sex-determining gene, Sry, have revealed that sex chromosomal effects may be associated with particular types of sex-linked differences such as aggression levels, social interaction, and autoimmune diseases, independently of sex steroid-mediated effects. In addition, studies on naturally occurring, rare phenomena such as gynandromorphic birds and experimentally constructed chimeras in which the composition of sex chromosomes in the brain differs from that in the other parts of the body, indicated that sex chromosomes play certain direct roles in the sex-specific differentiation of the gonads and the brain. In this article, we review the relative contributions of sex steroids and sex chromosomes in the determination of brain functions related to sexual behavior and reproductive physiology in mammals and birds.

  17. CAST-IRONS AT HIGH TEMPERATURES

    Directory of Open Access Journals (Sweden)

    A. N. Krutilin

    2008-01-01

    Full Text Available The results of investigations of physical-mechanical characteristics of cast iron slugs, received by semicontinuos way of casting, at temperatures from 850 up to 1100^ С are given. 

  18. Evolution of Social Insect Polyphenism Facilitated by the Sex Differentiation Cascade

    DEFF Research Database (Denmark)

    Klein, Antonia; Schultner, Eva; Lowak, Helena;

    2016-01-01

    -specific expression across life stages in the ant Cardiocondyla obscurior. We hypothesize that genes in the sex differentiation cascade evolved perception of alternative input signals for caste differentiation (i.e. environmental or genetic cues), and that their inherent switch-like and epistatic behavior facilitated......The major transition to eusociality required the evolution of a switch to canalize development into either a reproductive or a helper, the nature of which is currently unknown. Following predictions from the 'theory of facilitated variation', we identify sex differentiation pathways as promising...... candidates because of their pre-adaptation to regulating development of complex phenotypes. We show that conserved core genes, including the juvenile hormone-sensitive master sex differentiation gene doublesex (dsx) and a krüppel homolog 2 (kr-h2) with putative regulatory function, exhibit both sex and morph...

  19. Materials for Advanced Ultrasupercritical Steam Turbines Task 4: Cast Superalloy Development

    Energy Technology Data Exchange (ETDEWEB)

    Thangirala, Mani

    2015-09-30

    The Steam Turbine critical stationary structural components are high integrity Large Shell and Valve Casing heavy section Castings, containing high temperature steam under high pressures. Hence to support the development of advanced materials technology for use in an AUSC steam turbine capable of operating with steam conditions of 760°C (1400°F) and 35 Mpa (5000 psia), Casting alloy selection and evaluation of mechanical, metallurgical properties and castability with robust manufacturing methods are mandated. Alloy down select from Phase 1 based on producability criteria and creep rupture properties tested by NETL-Albany and ORNL directed the consortium to investigate cast properties of Haynes 282 and Haynes 263. The goals of Task 4 in Phase 2 are to understand a broader range of mechanical properties, the impact of manufacturing variables on those properties. Scale up the size of heats to production levels to facilitate the understanding of the impact of heat and component weight, on metallurgical and mechanical behavior. GE Power & Water Materials and Processes Engineering for the Phase 2, Task 4.0 Castings work, systematically designed and executed casting material property evaluation, multiple test programs. Starting from 15 lbs. cylinder castings to world’s first 17,000 lbs. poured weight, heavy section large steam turbine partial valve Haynes 282 super alloy casting. This has demonstrated scalability of the material for steam Turbine applications. Activities under Task 4.0, Investigated and characterized various mechanical properties of Cast Haynes 282 and Cast Nimonic 263. The development stages involved were: 1) Small Cast Evaluation: 4 inch diam. Haynes 282 and Nimonic 263 Cylinders. This provided effects of liquidus super heat range and first baseline mechanical data on cast versions of conventional vacuum re-melted and forged Ni based super alloys. 2) Step block castings of 300 lbs. and 600 lbs. Haynes 282 from 2 foundry heats were evaluated which

  20. CONTINUOUSLY-CYCLIC CASTING OF HOLLOW CYLINDER SLUGS OF HIGH-CHROMIUM CAST IRON

    Directory of Open Access Journals (Sweden)

    E. I. Marukovich

    2009-01-01

    Full Text Available The analysis of castings formation is presented and the package of measures dircted on increase of stability of casting process is developed. Parametres of casting of hollow cylindrical billets by the method of directional solidification out of white high-chromium cast iron are defined.

  1. Developing technological process of obtaining giality casts

    Directory of Open Access Journals (Sweden)

    A. Issagulov

    2014-10-01

    Full Text Available The article considers the process of manufacturing castings using sand-resin forms and alloying furnace. Were the optimal technological parameters of manufacturing shell molds for the manufacture of castings of heating equipment. Using the same upon receipt of castings by casting in shell molds furnace alloying and deoxidation of the metal will provide consumers with quality products and have a positive impact on the economy in general engineering.

  2. The Variation of Interface Formation with Slurry Viscosity Change in Side-By-Side Tape Casting

    DEFF Research Database (Denmark)

    Bulatova, Regina; Jabbari, Masoud; Andersen, Kjeld Bøhm;

    Homogenous and flexible adjacently graded tapes were produced by casting the organic-based slurries simultaneously. To develop side-by-side tape casing (SBSTC), the material optimization, modernization of the doctor blade design, and parameters control of such processes as casting, drying, de......-bindering and sintering were studied. Solvent and binder concentrations were varied in order to optimize co-casting flow, as well as the drying and sintering shrinkage. Tapes were evaluated in terms of rheological behavior of the slurries, the green and sintered tape microstructure, the quality of the interface area...

  3. Temperature and Thermal Stress Distribution for Metal Mold in Squeeze Casting Process

    Institute of Scientific and Technical Information of China (English)

    K.H.Chang; G.C.Jang; C.H.Lee; S.H.Lee

    2008-01-01

    In the squeeze casting process, loaded high pressure (over approximately 100 MPa) and high temperature influence the thermo-mechanical behavior and performance of the used metal mold. Therefore, to safely maintain the metal molds, the thermo-mechanical characteristics (temperature and thermal stress) of metal mold in the squeeze casting must be investigated. In this paper, temperature and thermal stress distribution of steel mold in squeeze casting process were investigated by using a three-dimensional non-steady heat conduction analysis and a three-dimensional thermal elastic-plastic analysis considering temperature-dependent thermo- physical and mechanical properties of the steel mold.

  4. When Your Child Needs a Cast

    Science.gov (United States)

    ... 1- to 2-Year-Old When Your Child Needs a Cast KidsHealth > For Parents > When Your Child Needs a Cast Print A A A What's in ... A cast wraps around the broken area and needs to be removed by a doctor when the ...

  5. Prediction of Microporosity in Shrouded Impeller Castings

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, S. Nelson, C.D.

    1998-09-01

    The purpose of this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Morris Bean and Company was to link computer models of heat and fluid flow with previously developed quality criteria for the prediction of microporosity in a Al-4.5% Cu alloy shrouded impeller casting. The results may be used to analyze the casting process design for the commercial production of 206 o alloy shrouded impeller castings. Test impeller castings were poured in the laboratory for the purpose of obtaining thermal data and porosity distributions. Also, a simulation of the test impeller casting was conducted and the results validated with porosity measurements on the test castings. A comparison of the predicted and measured microporosity distributions indicated an excellent correlation between experiments and prediction. The results of the experimental and modeling studies undertaken in this project indicate that the quality criteria developed for the prediction of microporosity in Al-4.5% Cu alloy castings can accurately predict regions of elevated microporosity even in complex castings such as the shrouded impeller casting. Accordingly, it should be possible to use quality criteria for porosity prediction in conjunction with computer models of heat and fluid flow to optimize the casting process for the production of shrouded impeller castings. Since high levels of microporosity may be expected to result in poor fatigue properties, casting designs that are optimized for low levels of microporosity should exhibit superior fatigue life.

  6. Pressure distribution in centrifugal dental casting.

    Science.gov (United States)

    Nielsen, J P

    1978-02-01

    Equations are developed for liquid metal pressure in centrifugal dental casting, given the instantaneous rotational velocity, density, and certain dimensions of the casting machine and casting pattern. A "reference parabola" is introduced making the fluid pressure concept more understandable. A specially designed specimen demonstrates experimentally the reference parabola at freezing.

  7. Squeeze Casting of Steel Weapon Components

    Science.gov (United States)

    1976-09-01

    equipment. The squeeze casting process also differs from rheo- casting.(10-12) Unlike the former, the rheocasting process (8) "Ferrous Die Casting...various phases of rheocasting . At least so far, the process has not been applied to fabrication of complex steel components of the type that are under

  8. Modeling wear of cast Ti alloys.

    Science.gov (United States)

    Chan, Kwai S; Koike, Marie; Okabe, Toru

    2007-05-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic-plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an alpha, alpha+beta or beta microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability.

  9. Understanding the Behavior of Systems Pharmacology Models Using Mathematical Analysis of Differential Equations: Prolactin Modeling as a Case Study.

    Science.gov (United States)

    Bakshi, S; de Lange, E C; van der Graaf, P H; Danhof, M; Peletier, L A

    2016-07-01

    In this tutorial, we introduce basic concepts in dynamical systems analysis, such as phase-planes, stability, and bifurcation theory, useful for dissecting the behavior of complex and nonlinear models. A precursor-pool model with positive feedback is used to demonstrate the power of mathematical analysis. This model is nonlinear and exhibits multiple steady states, the stability of which is analyzed. The analysis offers insight into model behavior and suggests useful parameter regions, which simulations alone could not.

  10. Understanding the Behavior of Systems Pharmacology Models Using Mathematical Analysis of Differential Equations: Prolactin Modeling as a Case Study

    Science.gov (United States)

    Bakshi, S; de Lange, EC; Danhof, M; Peletier, LA

    2016-01-01

    In this tutorial, we introduce basic concepts in dynamical systems analysis, such as phase‐planes, stability, and bifurcation theory, useful for dissecting the behavior of complex and nonlinear models. A precursor‐pool model with positive feedback is used to demonstrate the power of mathematical analysis. This model is nonlinear and exhibits multiple steady states, the stability of which is analyzed. The analysis offers insight into model behavior and suggests useful parameter regions, which simulations alone could not. PMID:27405001

  11. 基于自投影和灰度检索的视频帧中异常行为检测%Anomalous Behavior Detection in Video Sequence Based on Self-Casting Histogram and Gray Histogram

    Institute of Scientific and Technical Information of China (English)

    郭迎春; 吴鹏; 袁浩杰

    2012-01-01

    针对智能监控系统,提出了一种基于运动目标灰度直方图和自身投影直方图的检索匹配方法,能够快速实现视频序列中行人的运动方向异常检测.该方法结合目标的灰度直方图和自身投影直方图在人群中快速检索匹配目标,采用目标质心运动历史记录表连续记录目标质心和运动方向,通过比较各个目标的运动方向找出运动人群中的异常目标.实验结果表明,引入目标的自身投影直方图,比只利用灰度图的灰度信息有更高的检测准确性,同时历史移动记录表可完全胜任运动目标信息记录的任务.该方法计算量小,同时利用记录质心的移动速度能实时对目标的运动情况进行预测,对运动目标的相互遮藏有一定的鲁棒性.%For the intelligent video surveillance system, a motion object retrieval match approach is proposed, combining with the gray histogram and the self-casting histogram. It can rapidly detect an object with abnormal direction of motion. The method uses the feature combined with the gray and self-casting histograms to detect and match the object among crowds. And it uses the motion history record list of object centroid to continuously record the centroid of object and its motion direction. Besides, it compares the motion direction to find the abnormal object among moving crowds. The experiment result shows that compared with the method only employing the information of gray histogram, the accuracy of detection is improved after introducing object self-casting histogram, and the motion history record list is fully qualified to record the motion information of moving objects. The method has small amount of calculation and good robustness against objects covered by each other during their movement by recording the speeds of centroid motion.

  12. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Spheroidal Graphite Cast Iron(Ⅳ) 3.7 Segregation of SG iron The non-uniform distribution of solute elements during solidification results in the micro segregation of SG iron.As for the redistribution of elements in the phases of the solidification structure,there is no intrinsic difference between SG iron and grey iron[132].

  13. Search for chameleons with CAST

    DEFF Research Database (Denmark)

    Anastassopoulos, V.; Arik, M.; Aune, S.

    2015-01-01

    energy threshold used for axions from 1 keV to 400 eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600 eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of βΥ≤1011...

  14. Inoculation Effects of Cast Iron

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2012-12-01

    Full Text Available The paper presents a solidification sequence of graphite eutectic cells of A and D types, as well as globular and cementite eutectics. The morphology of eutectic cells in cast iron, the equations for their growth and the distances between the graphite precipitations in A and D eutectic types were analyzed. It is observed a critical eutectic growth rate at which one type of eutectic transformed into another. A mathematical formula was derived that combined the maximum degree of undercooling, the cooling rate of cast iron, eutectic cell count and the eutectic growth rate. One type of eutectic structure turned smoothly into the other at a particular transition rate, transformation temperature and transformational eutectic cell count. Inoculation of cast iron increased the number of eutectic cells with flake graphite and the graphite nodule count in ductile iron, while reducing the undercooling. An increase in intensity of inoculation caused a smooth transition from a cementite eutectic structure to a mixture of cementite and D type eutectic structure, then to a mixture of D and A types of eutectics up to the presence of only the A type of eutectic structure. Moreover, the mechanism of inoculation of cast iron was studied.

  15. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Spheroidal Graphite Cast Iron(Ⅲ) 3.6 Solidification morphology of SG iron Solidification morphology refers to the description of change,distribution and interrelationship of the solidification structures such as graphite spheroids,austenite,eutectic cells,etc.[99

  16. Tape casting of magnesium oxide.

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, Alicia; Corral, Erica L.; Loehman, Ronald E.; Bencoe, Denise Nora; Reiterer, Markus; Shah, Raja A.

    2008-02-01

    A tape casting procedure for fabricating ceramic magnesium oxide tapes has been developed as a method to produce flat sheets of sintered MgO that are thin and porous. Thickness of single layer tapes is in the range of 200-400 {micro}m with corresponding surface roughness values in the range of 10-20 {micro}m as measured by laser profilometry. Development of the tape casting technique required optimization of pretreatment for the starting magnesium oxide (MgO) powder as well as a detailed study of the casting slurry preparation and subsequent heat treatments for sintering and final tape flattening. Milling time of the ceramic powder, plasticizer, and binder mixture was identified as a primary factor affecting surface morphology of the tapes. In general, longer milling times resulted in green tapes with a noticeably smoother surface. This work demonstrates that meticulous control of the entire tape casting operation is necessary to obtain high-quality MgO tapes.

  17. CENTRIFUGAL CASTING OF ANTIFRICTION SILUMIN

    Directory of Open Access Journals (Sweden)

    V. Ju. Stetsenko

    2010-01-01

    Full Text Available It is shown that the way of centrifugal casting into water-cooled mould with vertical rotation axis enables to receive hollow slugs with diameter 100–250 mm, with height under 200 mm with wall thickness under 15 mm of antifriction silumin АК15М3, which will replace expensive antifriction bronze.

  18. Cern Axion Solar Telescope (CAST)

    CERN Multimedia

    2002-01-01

    The CERN Solar Axion Telescope, CAST, aims to shed light on a 30-year-old riddle of particle physics by detecting axions originating from the 15 million degree plasma in the Sun 's core. Axions were proposed as an extension to the Standard Model of particle physics to explain why CP violation is observed in weak but not strong interactions.

  19. The CAST time projection chamber

    Science.gov (United States)

    Autiero, D.; Beltrán, B.; Carmona, J. M.; Cebrián, S.; Chesi, E.; Davenport, M.; Delattre, M.; Di Lella, L.; Formenti, F.; Irastorza, I. G.; Gómez, H.; Hasinoff, M.; Lakic, B.; Luzón, G.; Morales, J.; Musa, L.; Ortiz, A.; Placci, A.; Rodrigurez, A.; Ruz, J.; Villar, J. A.; Zioutas, K.

    2007-06-01

    One of the three x-ray detectors of the CERN Axion Solar Telescope (CAST) experiment searching for solar axions is a time projection chamber (TPC) with a multi-wire proportional counter (MWPC) as a readout structure. Its design has been optimized to provide high sensitivity to the detection of the low intensity x-ray signal expected in the CAST experiment. A low hardware threshold of 0.8 keV is set to a safe level during normal data taking periods, and the overall efficiency for the detection of photons coming from conversion of solar axions is 62%. Shielding has been installed around the detector, lowering the background level to 4.10 × 10-5 counts cm-2 s-1 keV-1 between 1 and 10 keV. During phase I of the CAST experiment the TPC has provided robust and stable operation, thus contributing with a competitive result to the overall CAST limit on axion photon coupling and mass.

  20. Advanced Lost Foam Casting Technology

    Energy Technology Data Exchange (ETDEWEB)

    Charles E. Bates; Harry E. Littleton; Don Askeland; Taras Molibog; Jason Hopper; Ben Vatankhah

    2000-11-30

    This report describes the research done under the six tasks to improve the process and make it more functional in an industrial environment. Task 1: Pattern Pyrolysis Products and Pattern Properties Task 2: Coating Quality Control Task 3: Fill and Solidification Code Task 4: Alternate Pattern Materials Task 5: Casting Distortion Task 6: Technology Transfer

  1. Graphite Formation in Cast Iron

    Science.gov (United States)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  2. Differential genetic regulation of motor activity and anxiety-related behaviors in mice using an automated home cage task.

    Science.gov (United States)

    Kas, Martien J H; de Mooij-van Malsen, Annetrude J G; Olivier, Berend; Spruijt, Berry M; van Ree, Jan M

    2008-08-01

    Traditional behavioral tests, such as the open field test, measure an animal's responsiveness to a novel environment. However, it is generally difficult to assess whether the behavioral response obtained from these tests relates to the expression level of motor activity and/or to avoidance of anxiogenic areas. Here, an automated home cage environment for mice was designed to obtain independent measures of motor activity levels and of sheltered feeding preference during three consecutive days. Chronic treatment with the anxiolytic drug chlordiazepoxide (5 and 10 mg/kg/day) in C57BL/6J mice reduced sheltered feeding preference without altering motor activity levels. Furthermore, two distinct chromosome substitution strains, derived from C57BL/6J (host strain) and A/J (donor strain) inbred strains, expressed either increased sheltering preference in females (chromosome 15) or reduced motor activity levels in females and males (chromosome 1) when compared to C57BL/6J. Longitudinal behavioral monitoring revealed that these phenotypic differences maintained after adaptation to the home cage. Thus, by using new automated behavioral phenotyping approaches, behavior can be dissociated into distinct behavioral domains (e.g., anxiety-related and motor activity domains) with different underlying genetic origin and pharmacological responsiveness.

  3. Differential effects of early-life NMDA receptor antagonism on aspartame-impaired insulin tolerance and behavior.

    Science.gov (United States)

    Collison, Kate S; Inglis, Angela; Shibin, Sherin; Andres, Bernard; Ubungen, Rosario; Thiam, Jennifer; Mata, Princess; Al-Mohanna, Futwan A

    2016-12-01

    We have previously showed that lifetime exposure to aspartame, commencing in utero via the mother's diet, may impair insulin tolerance and cause behavioral deficits in adulthood via mechanisms which are incompletely understood. The role of the CNS in regulating glucose homeostasis has been highlighted by recent delineation of the gut-brain axis, in which N-methyl-d-aspartic acid receptors (NMDARs) are important in maintaining glucose homeostasis, in addition to regulating certain aspects of behavior. Since the gut-brain axis can be modulated by fetal programming, we hypothesized that early-life NMDAR antagonism may affect aspartame-induced glucose deregulation in adulthood, and may alter the aspartame behavioral phenotype. Accordingly, C57Bl/6J mice were chronically exposed to aspartame commencing in utero, in the presence and absence of maternal administration of the competitive NMDAR antagonist CGP 39551, from conception until weaning. Drug/diet interactions in adulthood glucocentric and behavioral parameters were assessed. Aspartame exposure elevated blood glucose and impaired insulin-induced glucose disposal during an insulin tolerance test, which could be normalized by NMDAR antagonism. The same effects were not observed in control diet mice, suggesting an early-life drug/diet interaction. Behavioral analysis of adult offspring indicated that NMDAR antagonism of control diet mice caused hyperlocomotion and impaired spatial navigation. Conversely hypolocomotion, reduced exploratory activity and increased anxiety-related behavior were apparent in aspartame diet mice with early-life NMDAR antagonism.

  4. Technological parameters of die casting and quality of casting from EN AC46500 alloy

    OpenAIRE

    2016-01-01

    Die casting represents the highest technological level of metal mold casting. This technology enables production of almost all final products without necessity of further processing. The important aspect of efficiency and production is a proper casting parameters setting. In the submitted paper following die casting parameters are analyzed: plunger pressing speed and pressure. The studied parameters most significantly affect a qualitative of castings from EN AC46500 alloy and they influence t...

  5. Tissue, developmental, and caste-specific expression of odorant binding proteins in a eusocial insect, the red imported fire ant, Solenopsis invicta

    Science.gov (United States)

    Zhang, Wei; Wanchoo, Arun; Ortiz-Urquiza, Almudena; Xia, Yuxian; Keyhani, Nemat O.

    2016-01-01

    Insects interact with the surrounding environment via chemoreception, and in social insects such as ants, chemoreception functions to mediate diverse behaviors including food acquisition, self/non-self recognition, and intraspecific communication. The invasive red imported fire ant, Solenopsis invicta, has spread worldwide, displaying a remarkable environmental adaptability. Odorant binding proteins (OBPs) are chemical compound carriers, involved in diverse physiological processes including odor detection and chemical transport. S. invicta contains a highly divergent 17-member OBP gene family, that includes an ant-specific expansion and the social organization implicated Gp-9 (OBP3) gene. A systematic gene expression analysis of the SiOBP repertoire was performed across social caste (workers, male and female alates), tissues (antennae, head, thorax, and abdomen), and developmental stages (egg, larvae, and pupae), revealing that although SiOBPs were expressed in the antennae, the major regions of expression were in the head and thorax across all castes, and the abdomen in male and female alates. SiOBPs were very highly expressed in female alates and at somewhat lower levels in male alates and workers. SiOBPs were differentially expressed, with unique signatures in various castes and tissues, suggesting functionality of SiOBPs beyond olfaction Expression patterns of SiOBP subgroups also showed relationships with their evolutionary relatedness. PMID:27765943

  6. Actin-associated protein palladin is required for migration behavior and differentiation potential of C2C12 myoblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ngoc Uyen Nhi; Liang, Vincent Roderick; Wang, Hao-Ven, E-mail: hvwang@mail.ncku.edu.tw

    2014-09-26

    Highlights: • Palladin is involved in myogenesis in vitro. • Palladin knockdown by siRNA increases myoblast proliferation, viability and differentiation. • Palladin knockdown decreases C2C12 myoblast migration ability. - Abstract: The actin-associated protein palladin has been shown to be involved in differentiation processes in non-muscle tissues. However, but its function in skeletal muscle has rarely been studied. Palladin plays important roles in the regulation of diverse actin-related signaling in a number of cell types. Since intact actin-cytoskeletal remodeling is necessary for myogenesis, in the present study, we pursue to investigate the role of actin-associated palladin in skeletal muscle differentiation. Palladin in C2C12 myoblasts is knocked-down using specific small interfering RNA (siRNA). The results show that down-regulation of palladin decreased migratory activity of mouse skeletal muscle C2C12 myoblasts. Furthermore, the depletion of palladin enhances C2C12 vitality and proliferation. Of note, the loss of palladin promotes C2C12 to express the myosin heavy chain, suggesting that palladin has a role in the modulation of C2C12 differentiation. It is thus proposed that palladin is required for normal C2C12 myogenesis in vitro.

  7. Differentiating Co-Occurring Behavior Problems in Children with ADHD: Patterns of Emotional Reactivity and Executive Functioning

    Science.gov (United States)

    Graziano, Paulo A.; McNamara, Joseph P.; Geffken, Gary R.; Reid, Adam M.

    2013-01-01

    Objective:This study examined whether "top-down" and "bottom-up" control processes can differentiate children with ADHD who exhibit co-occurring aggression and/or internalizing symptoms. Method: Participants included 74 children ("M" age = 10.7 years) with a "Diagnostic and Statistical Manual of Mental…

  8. Understanding different efficiency droop behaviors in InGaN-based near-UV, blue and green light-emitting diodes through differential carrier lifetime measurements

    CERN Document Server

    Wang, Lai; Wang, Jiaxing; Hao, Zhibiao; Luo, Yi; Sun, Changzheng; Han, Yanjun; Xiong, Bing; Wang, Jian; Li, Hongtao

    2016-01-01

    Efficiency droop effect under high injection in GaN-based light emitting diodes (LEDs) strongly depends on wavelength, which is still not well understood. In this paper, through differential carrier lifetime measurements on commercialized near-UV, blue, and green LEDs, their different efficiency droop behaviors are attributed to different carrier lifetimes, which are prolonged as wavelength increases. This relationship between carrier lifetime and indium composition of InGaN quantum well is believed owing to the polarization-induced quantum confinement Stark effect. Long carrier lifetime not only increases the probability of carrier leakage, but also results in high carrier concentration in quantum well. In other words, under the same current density, the carrier concentration in active region in near-UV LED is the lowest while that in green one is the highest. If considering the efficiency droop depending on carrier concentration, the behaviors of LEDs with different wavelengths do not show any abnormality. ...

  9. Copper isotope behavior during extreme magma differentiation and degassing: a case study on Laacher See phonolite tephra (East Eifel, Germany)

    Science.gov (United States)

    Huang, Jian; Liu, Sheng-Ao; Wörner, Gerhard; Yu, Huimin; Xiao, Yilin

    2016-09-01

    Copper (Cu) isotopic analyses were performed on a set of samples from the Laacher See tephra (LST) (Eifel, Germany) to investigate whether Cu isotopes are fractionated during extreme magma differentiation and degassing. The LST represents a continuous fractional crystallization series from parental basanite through mafic to highly differentiated phonolites. Samples analyzed here include phonolites of variable degrees of differentiation, phonolite-basanite hybrid rocks formed by mixing basanite and phonolite magmas, and basanite-derived mega-crystals (i.e., clinopyroxene, amphibole, phlogopite). In addition, we analyzed a series of mafic parental lavas from surrounding volcanic centers to constrain the Cu isotopic features of the Eifel mantle. Mafic phonolites show strong depletion in Cu compared to their parental basanites from ~50 to ~3 ppm, indicating sulfide fractionation during the basanite-to-phonolite differentiation. Mass balance calculations, based on the most Cu-rich hybrid rock (δ65Cu = -0.21 ‰, [Cu] = 46.2 ppm), show that the parental basanite magmas have δ65Cu of ca. -0.21 ‰, lighter than those of the mafic phonolites (~0.11 ‰). This suggests that sulfide fractionation preferentially removes the lighter Cu isotope (63Cu) in S-saturated magmas. By contrast, all phonolites have a limited range of Cu contents (1.1 to 4.0 ppm) with no systematic variations with S, suggesting that Cu is not controlled by sulfide fractionation during the evolution of mafic to highly differentiated phonolites. The identical δ65Cu values (0.11 ± 0.03 ‰, 2SD, n = 10) of the phonolites, irrespective of highly diverse composition and extents of differentiation, indicate that fractional crystallization of silicates (e.g., plagioclase, sanidine, amphibole, pyroxene, olivine), Fe-Ti-oxides and phosphate (e.g., apatite) generates insignificant Cu isotope fractionation. The lack of correlations between δ65Cu and volatile contents (e.g., S, Cl) in the LST sequence implies

  10. An optimization of injecting system in die casting

    Directory of Open Access Journals (Sweden)

    Wei WU

    2005-05-01

    Full Text Available After many years of development, die casting technology of metallic materials has been matured. In this paper,the lower-support and its injecting system were created with commercial software. And then the simulation software FLOW3D was applied to study the flow behavior of the melt during injection filling process. Both temperature field and defect distribution were simulated. Based on these results, the better injecting system with two additional overflows wasadopted.

  11. An optimization of injecting system in die casting

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    After many years of development, die casting technology of metallic materials has been matured. In this paper,the lower-support and its injecting system were created with commercial software. And then the simulation software FLOW3D was applied to study the flow behavior of the melt during injection filling process. Both temperature field and defect distribution were simulated. Based on these results, the better injecting system with two additional overflows was adopted.

  12. Effect of heat treatment on the microstructure, tensile properties, and fracture behavior of permanent mold Al-10 wt pct Si-0.6 wt pct Mg/SiC/10p composite castings

    Science.gov (United States)

    Samuel, F. H.; Samuel, A. M.

    1994-10-01

    The present study was undertaken to investigate the effect of solution treatment (in the temperature range 520 °C to 550 °C) and artificial aging (in the temperature range 140 °C to 180 °C) on the variation in the microstructure, tensile properties, and fracture mechanisms of Al-10 wt pct Si-0.6 wt pct Mg/SiC/10p composite castings. In the as-cast condition, the SiC particles are observed to act as nucleation sites for the eutectic Si particles. Increasing the solution temperature results in faster homogenization of the microstructure. Effect of solution temperature on tensile properties is evident only during the first 4 hours, after which hardly any difference is observed on increasing the solution temperature from 520 °C to 550 °C. The tensile properties vary significantly with aging time and temperature, with typical yield strength (YS), ultimate tensile strength (UTS), and percent elongation (EL) values of ˜300 MPa, ˜330 MPa, and ˜1.4 pct in the underaged condition, ˜330 MPa, ˜360 MPa, and ˜0.65 pct in the peakaged condition, and ˜323 MPa, ˜330 MPa, and ˜0.8 pct in the overaged condition. Prolonged solution treatment at 550 °C for 24 hours results in a slight improvement in the ductility of the aged test bars. The fracture surfaces exhibit a dimple morphology and cleavage of the SiC particles, the extent of SiC cracking increasing with increasing tensile strength and reaching a maximum in the overaged condition. Microvoids act as nucleation sites for the formation of secondary cracks that promote severe cracking of the SiC particles. A detailed discussion of the fracture mechanism is given.

  13. Role of thirst and visual barriers in the differential behavior displayed by streptozotocin-treated rats in the elevated plus-maze and the open field test.

    Science.gov (United States)

    Rebolledo-Solleiro, Daniela; Crespo-Ramírez, Minerva; Roldán-Roldán, Gabriel; Hiriart, Marcia; Pérez de la Mora, Miguel

    2013-08-15

    Conflicting results have been obtained by several groups when studying the effects of streptozotocin (STZ)-treated rats in the elevated plus-maze (EPM). Since thirst is a prominent feature in STZ-induced diabetic-like condition, we studied whether the walls of the closed arms of the EPM, by limiting the search for water in the environment, may contribute to the observed differential behavioral outcomes. The aim of this study was to ascertain whether visual barriers within the EPM have an influence on the behavior of STZ-treated rats in this test of anxiety. A striking similarity between STZ-treated (50 mg/kg, i.p., in two consecutive days) and water deprived rats (72 h) was found in exploratory behavior in the EPM, showing an anxiolytic-like profile. However the anxiolytic response of STZ-treated rats exposed to the EPM shifts into an anxiogenic profile when they are subsequently tested in the open-field test, which unlike the EPM is devoid of visual barriers. Likewise, water deprived rats (72 h) also showed an anxiogenic profile when they were exposed to the open-field test. Our results indicate that experimental outcomes based on EPM observations can be misleading when studying physiological or pathological conditions, e.g. diabetes, in which thirst may increase exploratory behavior.

  14. Differential patterns of amygdala and ventral striatum activation predict gender-specific changes in sexual risk behavior.

    Science.gov (United States)

    Victor, Elizabeth C; Sansosti, Alexandra A; Bowman, Hilary C; Hariri, Ahmad R

    2015-06-10

    Although the initiation of sexual behavior is common among adolescents and young adults, some individuals express this behavior in a manner that significantly increases their risk for negative outcomes including sexually transmitted infections. Based on accumulating evidence, we have hypothesized that increased sexual risk behavior reflects, in part, an imbalance between neural circuits mediating approach and avoidance in particular as manifest by relatively increased ventral striatum (VS) activity and relatively decreased amygdala activity. Here, we test our hypothesis using data from seventy 18- to 22-year-old university students participating in the Duke Neurogenetics Study. We found a significant three-way interaction between amygdala activation, VS activation, and gender predicting changes in the number of sexual partners over time. Although relatively increased VS activation predicted greater increases in sexual partners for both men and women, the effect in men was contingent on the presence of relatively decreased amygdala activation and the effect in women was contingent on the presence of relatively increased amygdala activation. These findings suggest unique gender differences in how complex interactions between neural circuit function contributing to approach and avoidance may be expressed as sexual risk behavior in young adults. As such, our findings have the potential to inform the development of novel, gender-specific strategies that may be more effective at curtailing sexual risk behavior.

  15. How to solve complex problems in foundry plants - future of casting simulation -

    Science.gov (United States)

    Ohnaka, I.

    2015-06-01

    Although the computer simulation of casting has progressed dramatically over the last decades, there are still many challenges and problems. This paper discusses how to solve complex engineering problems in foundry plants and what we should do in the future, in particular, for casting simulation. First, problem solving procedures including application of computer simulation are demonstrated and various difficulties are pointed-out exemplifying mainly porosity defects in sand castings of spheroidal graphite cast irons. Next, looking back conventional scientific and engineering research to understand casting phenomena, challenges and problems are discussed from problem solving view point, followed by discussion on the issues we should challenge such as how to integrate huge amount of dispersed knowledge in various disciplines, differentiation of science-oriented and engineering-oriented models, professional ethics, how to handle fluctuating materials, initial and boundary conditions, error accumulation, simulation codes as black-box, etc. Finally some suggestions are made on how to challenge the issues such as promotion of research on the simulation based on the science- oriented model and publication of reliable data of casting phenomena in complicated-shaped castings including reconsideration of the evaluation system.

  16. Flow of Steel in Mold Region During Continuous Casting

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xing-guo; ZHANG Wen-xiao; JIN Jun-ze; J. W. Evans

    2007-01-01

    The particle image velocimetry (PIV) technique was used to study the fluid flow phenomena that occurred during continuous casting, using a water model with dimensions of 1 840 mm×280 mm. Two types of solidified shells, i.e., the smooth type and the coarse type, were used to characterize the dendrite in order to simulate different liquid-solid interfacial conditions. The influence of the nozzle angle and the immersion depth of nozzle, as well as the casting speed on the flow behavior was investigated quantitatively. The results were as follows: (1) There are two large recirculations above and below the fluid jet in the mold, respectively, under the smooth interface condition. However, in the case of the dendrite solidified shell, it was found that the flow velocity of the fluid decreased and more smaller vortices appeared in the upper region of the mold. (2) The angle and the immersion depth of nozzle are two important factors affecting the flow pattern, and they are also capable of bringing about the change in the flow direction. (3) The higher the casting speed, the higher are the jet stream and the impacting point on the narrow face. However, the high casting speed causes serious fluctuation of the meniscus, and correspondingly leads to various defects.

  17. Mechanisms and mechanics of porosity formation in ductile iron castings

    Directory of Open Access Journals (Sweden)

    M. Perzyk

    2007-12-01

    Full Text Available Shrinkage defects in ductile iron castings can be of two basic types: shrinkage cavities associated with the liquid contraction prior to the expansion period of the iron as well as the porosity, which may appear even if the liquid shrinkage is fully compensated. In the present paper two possible mechanisms of the porosity are presented and analyzed. The first one is the Karsay’s mechanism based on the secondary shrinkage concept. The second one is the mechanism acting during the expansion period of the iron, first suggested by Ohnaka and co-authors and essentially modified by the present authors. The mechanical interactions between casting and mould are determined for the both mechanisms. Their analysis leads to the conclusion, that porosity forms during expansion period of the melt. The direct cause is the negative pressure which appears in the central part of the casting due to the differences in expansion coefficients of the fast cooling surface layer and slow cooling inner region. Observations concerning feeding behavior of ductile iron castings, based on this mechanism, agree well with industrial practice. The secondary shrinkage is not only needless to induce the porosity, but the corresponding mechanism of its occurrence, proposed by Karsay, does not seem to be valid.

  18. Quantitative comparison of caste differences in honeybee hemolymph.

    Science.gov (United States)

    Chan, Queenie W T; Howes, Charles G; Foster, Leonard J

    2006-12-01

    The honeybee, Apis mellifera, is an invaluable partner in agriculture around the world both for its production of honey and, more importantly, for its role in pollination. Honeybees are largely unexplored at the molecular level despite a long and distinguished career as a model organism for understanding social behavior. Like other eusocial insects, honeybees can be divided into several castes: the queen (fertile female), workers (sterile females), and drones (males). Each caste has different energetic and metabolic requirements, and each differs in its susceptibility to pathogens, many of which have evolved to take advantage of the close social network inside a colony. Hemolymph, arthropods' equivalent to blood, distributes nutrients throughout the bee, and the immune components contained within it form one of the primary lines of defense against invading microorganisms. In this study we have applied qualitative and quantitative proteomics to gain a better understanding of honeybee hemolymph and how it varies among the castes and during development. We found large differences in hemolymph protein composition, especially between larval and adult stage bees and between male and female castes but even between adult workers and queens. We also provide experimental evidence for the expression of several unannotated honeybee genes and for the detection of biomarkers of a viral infection. Our data provide an initial molecular picture of honeybee hemolymph, to a greater depth than previous studies in other insects, and will pave the way for future biochemical studies of innate immunity in this animal.

  19. Differential behavioral outcomes of 3,4-methylenedioxymethamphetamine (MDMA-ecstasy in anxiety-like responses in mice

    Directory of Open Access Journals (Sweden)

    V. Ferraz-de-Paula

    2011-05-01

    Full Text Available Anxiolytic and anxiogenic-like behavioral outcomes have been reported for methylenedioxymethamphetamine (MDMA or ecstasy in rodents. In the present experiment, we attempted to identify behavioral, hormonal and neurochemical outcomes of MDMA treatment to clarify its effects on anxiety-related responses in 2-month-old Balb/c male mice (25-35 g; N = 7-10 mice/group. The behavioral tests used were open field, elevated plus maze, hole board, and defensive behavior against predator odor. Moreover, we also determined striatal dopamine and dopamine turnover, and serum corticosterone levels. MDMA was injected ip at 0.2, 1.0, 5.0, 8.0, 10, or 20 mg/kg. MDMA at 10 mg/kg induced the following significant (P < 0.05 effects: a a dose-dependent increase in the distance traveled and in the time spent moving in the open field; b decreased exploratory activity in the hole board as measured by number of head dips and time spent in head dipping; c increased number of open arm entries and increased time spent in open arm exploration in the elevated plus maze; d increased time spent away from an aversive stimulus and decreased number of risk assessments in an aversive odor chamber; e increased serum corticosterone levels, and f increased striatal dopamine level and turnover. Taken together, these data suggest an anxiogenic-like effect of acute MDMA treatment, despite the fact that behavioral anxiety expression was impaired in some of the behavioral tests used as a consequence of the motor stimulating effects of MDMA.

  20. Continuous squeeze casting process by mass production

    Institute of Scientific and Technical Information of China (English)

    Yun Xia; Rich Jacques

    2006-01-01

    Squeeze casting has become the most competitive casting process in the automotive industry because of its many advantages over high pressure die casting (HPDC). Many squeeze casting R & D and small amount volume making have been implemented around the world, but the mass production control still exists problem. SPX Contech squeeze casting process P2000 successfully achieved the goal of mass production; it includes lower metal turbulence, less gas entrapment, minimum volumetric shrinkage, and thus less porosity. Like other casting processes, however, the quality of squeeze castings is still sensitive to process control and gate and runner design. Casting defects can form in both die-filling and metal solidification phases. The occurrence of casting defects is directly attributed to improper adjustment or lack of control of process parameters including metal filling velocity, temperature, dwell time, cooling pattern, casting design, and etc. This paper presents examples using P2000 techniques to improve part quality in the following areas: runner & gate design, casting & runner layout in the die, squeeze pin application, high thermal conductivityinserts, cooling/heating systems, spray & lubricant techniques,and part stress calculation from shrinkage or displacement prediction after stress relief.

  1. Prediction of Part Distortion in Die Casting

    Energy Technology Data Exchange (ETDEWEB)

    R. Allen Miller

    2005-03-30

    The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

  2. Process development of thin strip steel casting

    Energy Technology Data Exchange (ETDEWEB)

    Sussman, R.C.; Williams, R.S.

    1990-12-01

    An important new frontier is being opened in steel processing with the emergence of thin strip casting. Casting steel directly to thin strip has enormous benefits in energy savings by potentially eliminating the need for hot reduction in a hot strip mill. This has been the driving force for numerous current research efforts into the direct strip casting of steel. The US Department of Energy initiated a program to evaluate the development of thin strip casting in the steel industry. In earlier phases of this program, planar flow casting on an experimental caster was studied by a team of engineers from Westinghouse Electric corporation and Armco Inc. A subsequent research program was designed as a fundamental and developmental study of both planar and melt overflow casting processes. This study was arranged as several separate and distinct tasks which were often completed by different teams of researchers. An early task was to design and build a water model to study fluid flow through different designs of planar flow casting nozzles. Another important task was mathematically modeling of melt overflow casting process. A mathematical solidification model for the formation of the strip in the melt overflow process was written. A study of the material and conditioning of casting substrates was made on the small wheel caster using the melt overflow casting process. This report discusses work on the development of thin steel casting.

  3. Simulating a high pressure die casting

    Energy Technology Data Exchange (ETDEWEB)

    Goldak, J.; Zhou, J.; Downey, D.; Aldea, V.; Li, G.; Mocanita, M. [Carleton Univ., Ottawa, Ontario (Canada)

    2000-07-01

    High pressure die casting is simulated for parts with complex geometry such as a large automotive transmission case. The closed die is filled in approximately 40 ms, the casting cools in the closed die for approximately 40s, to open the die, eject the casting and spray the die cavity surface requires another 40s. This 3D cyclic process is simulated using the following coupled composite solvers: the energy equation in the die and in the casting with solidification; filling of the casting by a droplet or a Navier-Stokes solver, and thermal stress analysis of the casting machine, casting and die during the cycle. This thermal analysis can be done for both starting and stopping transients and for the cyclic steady state. The software enables this analysis to be done almost automatically by designers. (author)

  4. Gender-based Differential Item Functioning in the Application of the Theory of Planned Behavior for the Study of Entrepreneurial Intentions

    Science.gov (United States)

    Zampetakis, Leonidas A.; Bakatsaki, Maria; Litos, Charalambos; Kafetsios, Konstantinos G.; Moustakis, Vassilis

    2017-01-01

    Over the past years the percentage of female entrepreneurs has increased, yet it is still far below of that for males. Although various attempts have been made to explain differences in mens’ and women’s entrepreneurial attitudes and intentions, the extent to which those differences are due to self-report biases has not been yet considered. The present study utilized Differential Item Functioning (DIF) to compare men and women’s reporting on entrepreneurial intentions. DIF occurs in situations where members of different groups show differing probabilities of endorsing an item despite possessing the same level of the ability that the item is intended to measure. Drawing on the theory of planned behavior (TPB), the present study investigated whether constructs such as entrepreneurial attitudes, perceived behavioral control, subjective norms and intention would show gender differences and whether these gender differences could be explained by DIF. Using DIF methods on a dataset of 1800 Greek participants (50.4% female) indicated that differences at the item-level are almost non-existent. Moreover, the differential test functioning (DTF) analysis, which allows assessing the overall impact of DIF effects with all items being taken into account simultaneously, suggested that the effect of DIF across all the items for each scale was negligible. Future research should consider that measurement invariance can be assumed when using TPB constructs for the study of entrepreneurial motivation independent of gender. PMID:28386244

  5. The influence of calcium on technological properties and micropurity of steel castings

    Directory of Open Access Journals (Sweden)

    J. Hampl

    2016-07-01

    Full Text Available The paper analyzes the technological parameters, micro-purity and mechanical properties of castings of steel alloyed with calcium. The effect of calcium on the steel was analyzed on samples taken in the process of casting heavy castings and ingots of the weight of ranging from 40 000 to 60 000 kg. Samples for the determination of the liquidus temperature and the solidus temperature of cast steels were analysed using differential thermal analysis (DTA. The production of low alloyed steel grades was performed on the EAF - ASEA-SKF facilities and the production of highalloyed steels on the EAF - ASEA-SKF - SS-VOD facilities. The purity calcium was added into the steel by the injection of a stuffed profile.

  6. Partial Differential Equations of Physics

    OpenAIRE

    Geroch, Robert

    1996-01-01

    Apparently, all partial differential equations that describe physical phenomena in space-time can be cast into a universal quasilinear, first-order form. In this paper, we do two things. First, we describe some broad features of systems of differential equations so formulated. Examples of such features include hyperbolicity of the equations, constraints and their roles (e.g., in connection with the initial-value formulation), how diffeomorphism freedom is manifest, and how interactions betwee...

  7. Understanding the Behavior of Systems Pharmacology Models Using Mathematical Analysis of Differential Equations : Prolactin Modeling as a Case Study

    NARCIS (Netherlands)

    Bakshi, S.D.; Lange, de E.C.M.; Graaf, van der P.H.; Danhof, M.; Peletier, L.A.

    2016-01-01

    In this tutorial, we introduce basic concepts in dynamical systems analysis, such as phase-planes, stability, and bifurcation theory, useful for dissecting the behavior of complex and nonlinear models. A precursor-pool model with positive feedback is used to demonstrate the power of mathematical ana

  8. Differentiated Effects of Sensory Activities as Abolishing Operations via Non-Contingent Reinforcement on Academic and Aberrant Behavior

    Science.gov (United States)

    Mancil, G. Richmond; Haydon, Todd; Boman, Marty

    2016-01-01

    The purpose of the study was to evaluate the effectiveness of sensory activities used as antecedent interventions on the percentage correct on academic tasks and rate of aberrant behavior in three elementary aged children with Autism Spectrum Disorders (ASD). Study activities were conducted in an after school program for children with ASD where…

  9. Differential modulation of lateral septal vasopressin receptor blockade in spatial learning, social recognition, and anxiety-related behaviors in rats

    NARCIS (Netherlands)

    Everts, HGJ; Koolhaas, JM

    1999-01-01

    The role of lateral septal vasopressin (VP) in the modulation of spatial memory, social memory, and anxiety-related behavior was studied in adult, male Wistar rats. Animals were equipped with osmotic minipumps delivering the VP-antagonist d(CH2)5-D-Tyr(Et)VAVP (1 ng/0.5 mu l per h) bilaterally into

  10. Getting a Good Start in School: Differential Effects of "INSIGHTS" on the Behaviors and Engagement of Children with Challenging Temperaments

    Science.gov (United States)

    O'Connor, Erin E.; McCormick, Meghan P.; Cappella, Elise; McClowry, Sandee G.

    2014-01-01

    Not all children begin kindergarten ready to learn. Young children who exhibit dysregulated or disruptive behavior in the classroom have fewer opportunities to learn and consequently achieve lower levels of academic skills (Arnold et al., 2006; Raver, Garner, & Smith-Donald, 2007). A growing body of literature has examined how children's…

  11. Inner surface roughness of complete cast crowns made by centrifugal casting machines.

    Science.gov (United States)

    Ogura, H; Raptis, C N; Asgar, K

    1981-05-01

    Six variables that could affect the surface roughness of a casting were investigated. The variables were (1) type of alloy, (2) mold temperature, (3) metal casting temperature, (4) casting machine, (5) sandblasting, and (6) location of each section. It was determined that the training portion of a complete cast crown had rougher surfaces than the leading portion. Higher mold and casting temperatures produced rougher castings, and this effect was more pronounced in the case of the base metal alloy. Sandblasting reduced the roughness, but produced scratched surfaces. Sandblasting had a more pronounced affect on the surface roughness of the base metal alloy cast either at a higher mold temperature or metal casting temperature. The morphology and the roughness profile of the original cast surface differed considerably with the type of alloy used.

  12. Maternal postpartum corticosterone and fluoxetine differentially affect adult male and female offspring on anxiety-like behavior, stress reactivity, and hippocampal neurogenesis.

    Science.gov (United States)

    Gobinath, Aarthi R; Workman, Joanna L; Chow, Carmen; Lieblich, Stephanie E; Galea, Liisa A M

    2016-02-01

    Postpartum depression (PPD) affects approximately 15% of mothers, disrupts maternal care, and can represent a form of early life adversity for the developing offspring. Intriguingly, male and female offspring are differentially vulnerable to the effects of PPD. Antidepressants, such as fluoxetine, are commonly prescribed for treating PPD. However, fluoxetine can reach offspring via breast milk, raising serious concerns regarding the long-term consequences of infant exposure to fluoxetine. The goal of this study was to examine the long-term effects of maternal postpartum corticosterone (CORT, a model of postpartum stress/depression) and concurrent maternal postpartum fluoxetine on behavioral, endocrine, and neural measures in adult male and female offspring. Female Sprague-Dawley dams were treated daily with either CORT or oil and fluoxetine or saline from postnatal days 2-23, and offspring were weaned and left undisturbed until adulthood. Here we show that maternal postpartum fluoxetine increased anxiety-like behavior and impaired hypothalamic-pituitary-adrenal (HPA) axis negative feedback in adult male, but not female, offspring. Furthermore, maternal postpartum fluoxetine increased the density of immature neurons (doublecortin-expressing) in the hippocampus of adult male offspring but decreased the density of immature neurons in adult female offspring. Maternal postpartum CORT blunted HPA axis negative feedback in males and tended to increase density of immature neurons in males but decreased it in females. These results indicate that maternal postpartum CORT and fluoxetine can have long-lasting effects on anxiety-like behavior, HPA axis negative feedback, and adult hippocampal neurogenesis and that adult male and female offspring are differentially affected by these maternal manipulations.

  13. Pressure rig for repetitive casting

    Science.gov (United States)

    Vasquez, Peter (Inventor); Hutto, William R. (Inventor); Philips, Albert R. (Inventor)

    1989-01-01

    The invention is a pressure rig for repetitive casting of metal. The pressure rig performs like a piston for feeding molten metal into a mold. Pressure is applied to an expandable rubber diaphragm which expands like a balloon to force the metal into the mold. A ceramic cavity which holds molten metal is lined with blanket-type insulating material, necessitating only a relining for subsequent use and eliminating the lengthy cavity preparation inherent in previous rigs. In addition, the expandable rubber diaphragm is protected by the insulating material thereby decreasing its vulnerability to heat damage. As a result of the improved design the life expectancy of the pressure rig contemplated by the present invention is more than doubled. Moreover, the improved heat protection has allowed the casting of brass and other alloys with higher melting temperatures than possible in the conventional pressure rigs.

  14. Search for chameleons with CAST

    Directory of Open Access Journals (Sweden)

    V. Anastassopoulos

    2015-10-01

    Full Text Available In this work we present a search for (solar chameleons with the CERN Axion Solar Telescope (CAST. This novel experimental technique, in the field of dark energy research, exploits both the chameleon coupling to matter (βm and to photons (βγ via the Primakoff effect. By reducing the X-ray detection energy threshold used for axions from 1 keV to 400 eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600 eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of βγ≲1011 for 1<βm<106.

  15. Search for chameleons with CAST

    CERN Document Server

    Anastassopoulos, V; Aune, S; Barth, K; Belov, A; Bräuninger, H; Cantatore, G; Carmona, J M; Cetin, S A; Christensen, F; Collar, J I; Dafni, T; Davenport, M; Desch, K; Dermenev, A; Eleftheriadis, C; Fanourakis, G; Ferrer-Ribas, E; Friedrich, P; Galán, J; García, J A; Gardikiotis, A; Garza, J G; Gazis, E N; Geralis, T; Giomataris, I; Hailey, C; Haug, F; Hasinoff, M D; Hofmann, D H H; Iguaz, F J; Irastorza, I G; Jacoby, J; Jakobsen, A; Jakovčić, K; Kaminski, J; Karuza, M; Kavuk, M; Krčmar, M; Krieger, C; Krüger, A; Lakić, B; Laurent, J M; Liolios, A; Ljubičić, A; Luzón, G; Neff, S; Ortega, I; Papaevangelou, T; Pivovarov, M J; Raffelt, G; Riege, H; Rosu, M; Ruz, J; Savvidis, I; Solanki, S K; Vafeiadis, T; Villar, J A; Vogel, J K; Yildiz, S C; Zioutas, K; Brax, P; Lavrentyev, I; Upadhye, A

    2015-01-01

    In this work we present a search for (solar) chameleons with the CERN Axion Solar Telescope (CAST). This novel experimental technique, in the field of dark energy research, exploits both the chameleon coupling to matter ($\\beta_{\\rm m}$) and to photons ($\\beta_{\\gamma}$) via the Primakoff effect. By reducing the X-ray detection energy threshold used for axions from 1$\\,$keV to 400$\\,$eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600$\\,$eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of $\\beta_{\\gamma}\\!\\lesssim\\!10^{11}$ for $1<\\beta_{\\rm m}<10^6$.

  16. Innovative algorithm for cast detection

    Science.gov (United States)

    Gasparini, Francesca; Schettini, Raimondo; Gallina, Paolo

    2001-12-01

    The paper describes a method for detecting a color cast (i.e. a superimposed dominant color) in a digital image without any a priori knowledge of its semantic content. The color gamut of the image is first mapped in the CIELab color space. The color distribution of the whole image and of the so-called Near Neutral Objects (NNO) is then investigated using statistical tools then, to determine the presence of a cast. The boundaries of the near neutral objects in the color space are set adaptively by the algorithm on the basis of a preliminary analysis of the image color gamut. The method we propose has been tuned and successfully tested on a large data set of images, downloaded from personal web-pages or acquired using various digital and traditional cameras.

  17. Developmental epigenetic programming of caste-specific differences in social insects: an impact on longevity.

    Science.gov (United States)

    Vaiserman, Alexander

    2014-01-01

    Social insects are an excellent model system for a deeper understanding of the mechanisms of longevity determination because they have a caste system in which the same genome, due to the differential gene expression, can produce both a short-lived worker and a long-lived queen. For example, in the honeybee, Apis mellifera, queens develop from fertilized eggs that are genetically not different from the eggs that develop into workers. They have, however, a much larger size and specialized anatomy, develop substantially faster and live much longer than worker bees. In many social insects including bees, ants, wasps, and termites, queens and workers show up to a 100-fold difference in lifespan, with reproductive queens having longer longevity than non-reproductive workers. Caste differentiation in social insect species is known to be dependent on the larval nutritional environment. In the honeybee, the caste switching is determined by distinguished feeding of larvae. There is accumulating evidence that queen phenotype is driven by epigenetic mechanisms of gene regulation. Dietary differences during the larval development have been found to lead to differential DNA methylation. This results in caste-biased patterns of gene expression, which, in turn, leads to caste-biased phenotypes, such as short-lived workers and long-lived queens. The investigation of physiological, biochemical and molecular aspects of the biology of queens and workers seems to be a promising way to identifying pathways that control longevity and to developing the treatments designed to influence these pathways.

  18. Gating of Permanent Molds for Aluminum Casting

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang

    2004-01-01

    This report summarizes a two-year project, DE-FC07-011D13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was to determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings. Equipment and procedure for real time X-Ray radiography of molten aluminum flow into permanent molds have been developed. Other studies have been conducted using water flow and behavior of liquid aluminum in sand mold using real time photography. This investigation utilizes graphite molds transparent to X-Rays making it possible to observe the flow pattern through a number of vertically oriented grating systems. These have included systems that are choked at the base of a rounded vertical sprue and vertical gating systems with a variety of different ingates into the bottom of a mold cavity. These systems have also been changed to include gating systems with vertical and horizontal gate configurations. Several conclusions can be derived from this study. A sprue-well, as designed in these experiments, does not eliminate the vena contracta. Because of the swirling at the sprue-base, the circulating metal begins to push the entering metal stream toward the open runner mitigating the intended effect of the sprue-well. Improved designs of

  19. Rapid Cycle Casting of Steel

    Science.gov (United States)

    1981-07-01

    such as macrosegregation, hot tears, and blowholes are also difficult to control. Rheocasting l on the other hand, is a recent development which...viscosity. Advantages of the rheocasting process are: * Reduced attack of die or mold because of the reduced tempera- ture (by 1000 C for steel) and...4W W ’ V6W 4 1.2 THE SD PROCESS Many metals, including steel, can be cast at still lower tempera- soliifiction(2) tures than rheocasting by

  20. mtDNA variation in caste populations of Andhra Pradesh, India.

    Science.gov (United States)

    Bamshad, M; Fraley, A E; Crawford, M H; Cann, R L; Busi, B R; Naidu, J M; Jorde, L B

    1996-02-01

    Various anthropological analyses have documented extensive regional variation among populations on the subcontinent of India using morphological, protein, blood group, and nuclear DNA polymorphisms. These patterns are the product of complex population structure (genetic drift, gene flow) and a population history noted for numerous branching events. As a result, the interpretation of relationships among caste populations of South India and between Indians and continental populations remains controversial. The Hindu caste system is a general model of genetic differentiation among endogamous populations stratified by social forces (e.g., religion and occupation). The mitochondrial DNA (mtDNA) molecule has unique properties that facilitate the exploration of population structure. We analyzed 36 Hindu men born in Andhra Pradesh who were unrelated matrilineally through at least 3 generations and who represent 4 caste populations: Brahmin (9), Yadava (10), Kapu (7), and Relli (10). Individuals from Africa (36), Asia (36), and Europe (36) were sampled for comparison. A 200-base-pair segment of hypervariable segment 2 (HVS2) of the mtDNA control region was sequenced in all individuals. In the Indian castes 25 distinct haplotypes are identified. Aside from the Cambridge reference sequence, only two haplotypes are shared between caste populations. Middle castes form a highly supported cluster in a neighbor-joining network. Mean nucleotide diversity within each caste is 0.015, 0.012, 0.011, and 0.012 for the Brahmin, Yadava, Kapu, and Relli, respectively. mtDNA variation is highly structured between castes (GST = 0.17; p caste populations of Andhra Pradesh cluster more often with Africans than with Asians or Europeans. This is suggestive of admixture with African populations.

  1. Computer precision simulation for titanium casting centrifugal mold filling of prescision titanium castings

    Directory of Open Access Journals (Sweden)

    Daming XU

    2004-08-01

    Full Text Available Computer simulation codes were developed based on proposed mathematical model for centrifugal mold filling processes and previous computer software for 3D mold filling and solidification of castings. Sample simulations were implemented for mold filling processes of precision titanium castings under gravity and different centrifugal casting techniques. The computation results show that the alloy melt has a much stronger mold filling ability for thin section castings unde a centrifugal force field than that only under the gravity. A "return back" mold filling manner is showed to be a reasonable technique for centrifugal casting processes, especially for thin section prcision castings.

  2. Strongly directional and differential swimming behavior of an adult female white shark, Carcharodon carcharias (Chondrichthyes: Lamnidae from Guadalupe Island, Mexico

    Directory of Open Access Journals (Sweden)

    Ramón Bonfil

    2015-03-01

    Full Text Available We report on an adult female white shark tracked for 288 days and 7,100 km in the NE Pacific Ocean. The shark, tagged with a real-time satellite tag off Guadalupe Island, Mexico in October 2006, remained around the island for 3.5 months but left in early February 2007 for a ca. 3,900 km westward migration. Heading and swimming speed data showed that: a the arc-like route followed by this shark during oceanic travel involved strongly directional rapid movement, and b once the shark arrived to a specific (ca. 680 km wide area located 790 km north-northeast of the Hawaiian Islands, it switched into a distinct roaming behavior. The shark remained in this roaming area from late March to at least late July 2007. We show that real-time satellite tags can provide unique and valuable information about the migratory behavior of white sharks.

  3. Differential typology and prognosis for dissexual behavior--a follow-up study of previously expert-appraised child molesters.

    Science.gov (United States)

    Beier, K M

    1998-01-01

    In terms of identifying socially-dysfunctional forms of sexuality--regardless of the legal valuation--dissexuality is defined as "an expression of social failure in sexual behavior." This failure was the subject of a longitudinal analysis of 186 expert-appraised pedophile sexual delinquents at the University of Kiel from 1945 through 1981. Of the child molesters 121 were followed up between September 1990 and September 1992 and 100 were personally contacted. The goal was to empirically develop prognosis criteria, given knowledge of the former delinquents' social development as well as sexual/dissexual practices, which could be of both forensic and interdisciplinary use. Among the bi- and homosexually-orientated pedophiles, the number of offenders for which the act is one of "compensation" was half of the initial collective. In contrast, this number was three-quarters for the heterosexually-orientated perpetrators. Correspondingly, the other half of the bi- and homosexually-orientated pedophiles were either exclusive-type or non-exclusive-type pedophiles (the so-called "true" pedophiles). Among the heterosexually-orientated offenders, the number was only one-quarter. According to the empirical data, we may expect a biographically continuing potential of dissexual behavior for only the exclusive and the non-exclusive type of pedophilia. Most of the relapsed dissexual activities showed up a long time after the expert's report. This is true for both the heterosexually- and the bi- and homosexually orientated groups. The present evaluation of the results allows assignment of behavior for certain delinquent typologies restricted to life phases or lifelong dissexual behavior.

  4. Antiretroviral treatment initiation does not differentially alter neurocognitive functioning over time in youth with behaviorally acquired HIV

    OpenAIRE

    Nichols, Sharon L.; Bethel, James; Kapogiannis, Bill G.; Li, Tiandong; Woods, Steven P.; Patton, E. Doyle; Ren, Weijia; Thornton, Sarah E.; Major-Wilson, Hanna O.; Puga, Ana M.; Sleasman, John W.; Rudy, Bret J; Craig M Wilson; Garvie, Patricia A.; ,

    2015-01-01

    Although youth living with behaviorally acquired HIV (YLWH) are at risk for cognitive impairments, the relationship of impairments to HIV and potential to improve with antiretroviral therapy (ART) are unclear. This prospective observational study was designed to examine the impact of initiation and timing of ART on neurocognitive functioning in YLWH in the Adolescent Medicine Trials Network for HIV/AIDS Interventions. Treatment naïve YLWH age 18–24 completed baseline and four additional asses...

  5. Prenatal loud music and noise: differential impact on physiological arousal, hippocampal synaptogenesis and spatial behavior in one day-old chicks.

    Directory of Open Access Journals (Sweden)

    Tania Sanyal

    Full Text Available Prenatal auditory stimulation in chicks with species-specific sound and music at 65 dB facilitates spatial orientation and learning and is associated with significant morphological and biochemical changes in the hippocampus and brainstem auditory nuclei. Increased noradrenaline level due to physiological arousal is suggested as a possible mediator for the observed beneficial effects following patterned and rhythmic sound exposure. However, studies regarding the effects of prenatal high decibel sound (110 dB; music and noise exposure on the plasma noradrenaline level, synaptic protein expression in the hippocampus and spatial behavior of neonatal chicks remained unexplored. Here, we report that high decibel music stimulation moderately increases plasma noradrenaline level and positively modulates spatial orientation, learning and memory of one day-old chicks. In contrast, noise at the same sound pressure level results in excessive increase of plasma noradrenaline level and impairs the spatial behavior. Further, to assess the changes at the molecular level, we have quantified the expression of functional synapse markers: synaptophysin and PSD-95 in the hippocampus. Compared to the controls, both proteins show significantly increased expressions in the music stimulated group but decrease in expressions in the noise group. We propose that the differential increase of plasma noradrenaline level and altered expression of synaptic proteins in the hippocampus are responsible for the observed behavioral consequences following prenatal 110 dB music and noise stimulation.

  6. Prenatal loud music and noise: differential impact on physiological arousal, hippocampal synaptogenesis and spatial behavior in one day-old chicks.

    Science.gov (United States)

    Sanyal, Tania; Kumar, Vivek; Nag, Tapas Chandra; Jain, Suman; Sreenivas, Vishnu; Wadhwa, Shashi

    2013-01-01

    Prenatal auditory stimulation in chicks with species-specific sound and music at 65 dB facilitates spatial orientation and learning and is associated with significant morphological and biochemical changes in the hippocampus and brainstem auditory nuclei. Increased noradrenaline level due to physiological arousal is suggested as a possible mediator for the observed beneficial effects following patterned and rhythmic sound exposure. However, studies regarding the effects of prenatal high decibel sound (110 dB; music and noise) exposure on the plasma noradrenaline level, synaptic protein expression in the hippocampus and spatial behavior of neonatal chicks remained unexplored. Here, we report that high decibel music stimulation moderately increases plasma noradrenaline level and positively modulates spatial orientation, learning and memory of one day-old chicks. In contrast, noise at the same sound pressure level results in excessive increase of plasma noradrenaline level and impairs the spatial behavior. Further, to assess the changes at the molecular level, we have quantified the expression of functional synapse markers: synaptophysin and PSD-95 in the hippocampus. Compared to the controls, both proteins show significantly increased expressions in the music stimulated group but decrease in expressions in the noise group. We propose that the differential increase of plasma noradrenaline level and altered expression of synaptic proteins in the hippocampus are responsible for the observed behavioral consequences following prenatal 110 dB music and noise stimulation.

  7. The effects of Cr, Co, Al, Mo and Ta on the cyclic oxidation behavior of a prototype cast Ni-base superalloy based on a 2(5) composite statistically designed experiment

    Science.gov (United States)

    Barrett, C. A.

    1984-01-01

    A series of cast Ni-base superalloys were systematically varied at selected levels of Co, Cr, Mo, Ta, and Al. The elemental levels varied were Mo, 0 to 4 percent; Cr, 6 to 18 percent; Co, 0 to 20 percent, Ta, 0 to 8 percent; and Al, 3.25 to 6.25 percent. The cyclic oxidation resistance was determined from specific weight change data as a function of time for 1 hr cycles in static air at 1100 C. The significant terms in decreasing order of their importance were Al, Ta, Cr2, Al-Cr, Cr-Co, Co2, Al-Mo, Cr-Mo, Al-Al, and Mo-Ta. The Al term alone accounted for close to 82 percent of the explained variability. The estimating equation showed that the Al level was the most important and should be at its 6.25 wt % maximum value. The Mo and Ta levels should also be at their maximum 4 and 8 wt % respectively. The cobalt composition should be as low as possible, i.e., 0 wt%. The Cr level optimum varies depending on the other 4 levels. The X-ray diffaction results indicate the most protective scales are alumina/aluminate spinel stabilizized with a tri-rutile oxide high in Ta and Mo.

  8. On Quadratic Differential Forms

    NARCIS (Netherlands)

    Willems, J.C.; Trentelman, H.L.

    1998-01-01

    This paper develops a theory around the notion of quadratic differential forms in the context of linear differential systems. In many applications, we need to not only understand the behavior of the system variables but also the behavior of certain functionals of these variables. The obvious cases w

  9. [The cast structure after vacuum-pressure casting and centrifugal casting].

    Science.gov (United States)

    Finger, W; Jung, T; Quast, U

    1975-02-01

    Evaluation of polished sections revealed the following: 1. Grain size in marginal areas of the crown is, in general, smaller than it is in the occlusal region. 2. Grain size varies depending on the casting method applied. Differences in hardness were found only to a limited extent. They were not always in line with the grain structure. This phenomenon deviating from the rule cannot satisfactorily be explained. The piping distribution was in accordance with observations made so far.

  10. Application of Anand's constitutive model on twin roll casting process of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-dong; JU Dong-ying

    2006-01-01

    Twin-roll thin strip casting process combines casting and hot rolling into a single process,in which thermal stress and thermal mechanical stress were involved. Considering the high temperature gradient,the existing of liquid and solid regions and rolling deformation,suitable constitutive model is the key to describe the process. Anand's model is a temperature-dependent,rate-dependent and unified of creep and plasticity model and the Jaumann derivative was employed in Anand's model which makes the constitutive model frame-indifferent or objective,therefore the highly nonlinearities behavior in the twin-roll casting process can be simulated. The parameters of the Anand's model were regressed based on the compression tests of AZ31 magnesium alloy. The simulation results reveal that the Anand's model can well describe the deformation characteristics of twin-roll casting process. Based on the simulation results,the form of evolution equations in Anand's model was discussed.

  11. A Statistics-Based Cracking Criterion of Resin-Bonded Silica Sand for Casting Process Simulation

    Science.gov (United States)

    Wang, Huimin; Lu, Yan; Ripplinger, Keith; Detwiler, Duane; Luo, Alan A.

    2017-02-01

    Cracking of sand molds/cores can result in many casting defects such as veining. A robust cracking criterion is needed in casting process simulation for predicting/controlling such defects. A cracking probability map, relating to fracture stress and effective volume, was proposed for resin-bonded silica sand based on Weibull statistics. Three-point bending test results of sand samples were used to generate the cracking map and set up a safety line for cracking criterion. Tensile test results confirmed the accuracy of the safety line for cracking prediction. A laboratory casting experiment was designed and carried out to predict cracking of a cup mold during aluminum casting. The stress-strain behavior and the effective volume of the cup molds were calculated using a finite element analysis code ProCAST®. Furthermore, an energy dispersive spectroscopy fractographic examination of the sand samples confirmed the binder cracking in resin-bonded silica sand.

  12. BP Neural Network of Continuous Casting Technological Parameters and Secondary Dendrite Arm Spacing of Spring Steel

    Institute of Scientific and Technical Information of China (English)

    HANG Li-hong; WANG Ai-guo; TIAN Nai-yuan; ZHANG Wei-cun; FAN Qiao-li

    2011-01-01

    The continuous casting technological parameters have a great influence on the secondary dendrite arm spacing of the slab, which determines the segregation behavior of materials. Therefore, the identification of technological parameters of continuous casting process directly impacts the property of slab. The relationships between continuous casting technological parameters and cooling rate of slab for spring steel were built using BP neural network model, based on which, the relevant secondary dendrite arm spacing was calculated. The simulation calculation was also carried out using the industrial data. The simulation results show that compared with that of the traditional method, the absolute error of calculation result obtained with BP neural network model reduced from 0. 015 to 0. 0005, and the relative error reduced from 6, 76 % to 0.22 %. BP neural network model had a more precise accuracy in the optimization of continuous casting technological parameters.

  13. Differential expression of Arc in the mesocorticolimbic system is involved in drug and natural rewarding behavior in rats

    Institute of Scientific and Technical Information of China (English)

    Mu LI; Wen-jie LIU; Bin LU; Yu-hua WANG; Jing-gen LIU

    2013-01-01

    Aim:To investigate the different effects of heroin and milk in activating the corticostriatal system that plays a critical role in reward reinforcement learning.Methods:Male SD rats were trained daily for 15 d to self-administer heroin or milk tablets in a classic runway drug self-administration model.Immunohistochemical assay was used to quantify Arc protein expression in the medial prefrontal cortex (mPFC),the nucleus accumbens (NAc),the dorsomedial striatum (DMS) and the ventrolateral striatum (VLS) in response to chronic self-administration of heroin or milk tablets.NMDA receptor antagonist MK801 (0.1 mg/kg) or dopamine D1 receptor antagonist SCH23390 (0.03 mg/kg) were intravenously injected at the same time as heroin was infused intravenously.Results:Runway training with heroin resulted in robust enhancement of Arc expression in the mPFC,the NAc and the DMS on d 1,7,and 15,and in the VLS on d 1 and d 7.However,runway training with milk led to increased Arc expression in the mPFC,the NAc and the DMS only on d 7 and/or d 15 but not on d 1.Moreover,runway training with milk failed to induce increased Arc protein in the VLS.Both heroin-seeking behavior and Arc protein expression were blocked by MK801 or SCH23390 administration.Conclusion:The VLS is likely to be critically involved in drug-seeking behavior.The NMDA-and D1 receptor-dependent Arc expression is important in drug-seeking behavior.

  14. Differential behavioral reinforcement effects of dopamine receptor agonists in the rat with bilateral lesion of the posterior ventral tegmental area.

    Science.gov (United States)

    Ouachikh, Omar; Dieb, Wisam; Durif, Franck; Hafidi, Aziz

    2013-09-01

    Dopamine dysregulation syndrome in Parkinson's disease has been attributed to dopamine replacement therapies and/or a lesion of the dopaminergic system. The dopaminergic neuronal loss targets the substantia nigra and the ventral tegmental area (VTA). We hypothesize that dopamine replacement therapy is responsible for the potential reinforcement effect in Parkinson's disease by acting on the neuronal reward circuitry. Therefore this study was designed to explore the potential motivational effect of dopamine replacement therapy in bilateral VTA-lesioned animals. The posterior (p)VTA, which project to the nucleus accumbens (NAc) constitutes the major dopamine neuronal circuitry implicated in addictive disorders. Using the conditioned place preference (CPP) behavioral paradigm, we investigated the motivational effects of dopamine receptor agonists, and cocaine in rat with a 6-OHDA bilateral lesion of the pVTA. Amongst the dopamine receptor agonists used in this study only the D2R and D3R agonists (bromocriptine, PD128907 and pramipexole), induced a significant CPP in pVTA-lesioned animals. Dopamine receptor agonists did not induce behavioral sensitization in sham animals. Moreover, confocal D2R immunostaining analysis showed a significant increase in the number of D2R per cell body in the NAc shell of pVTA lesioned rats compared to sham. This result correlated, for the first time, the dopamine receptor agonists effect with DR2 overexpression in the NAc shell of pVTA-lesioned rats. In addition, cocaine, which is known to increase dopamine release, induced behavioral sensitization in sham group but not in dopamine deprived group. Thus, the later result highlighted the importance of pVTA-NAc dopaminergic pathway in positive reinforcements. Altogether these data suggested that the implication of the dopamine replacement therapy in the appearance of dopamine dysregulation syndrome in Parkinson's disease is probably due to both neuronal degeneration in the posterior VTA and

  15. Experimental investigations of fatigue characteristics of AC4CH cast aluminum alloys fabricated through rheocast and squeeze cast methods

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, N. [Graduate School, Toyohashi Univ. of Technology, Toyohashi-city, Aichi (Japan); Toda, H.; Kobayashi, T. [Faculty of Engineering, Toyohashi Univ. of Technology, Toyohashi-city, Aichi (Japan); Wade, N. [Topy Industries Ltd., Toyohashi-city, Aichi (Japan)

    2002-07-01

    This study investigates the fatigue characteristics of AC4CH cast aluminum alloys fabricated through the semi-solid metal (rheocasting) process by employing the inclined cooling plate technique with a wide range of spherical {alpha} size (38-160 {mu}m) and compares with those of the conventional squeeze casting. Rheocasting process employing an inclined cooling plate is based on the crystal separation theory. The results of measured microstructural parameters indicate that aspect ratio and size of eutectic Si and size of intermetallic compound decrease with the decrease in primary {alpha} size. The fatigue strength increases with decreases in primary {alpha} size and the material with the minimum primary {alpha} size (i.e. 38 {mu}m) shows 11.3% higher fatigue strength at 10{sup 7} cycles than that of the squeeze cast material. Although difference in damage accumulation behaviors during tensile loading is quantified by the in-situ studies, however, it does not seem to have discernable effect on the fatigue properties. The Si and intermetallic compound particles remain almost intact below 250 MPa and 200 MPa respectively in all of the materials and damage evolution occurs at the lowest stress level in the squeeze cast material. Moreover, the maximum fraction of the damaged particles depends upon the primary {alpha} size and reaches the maximum with the minimum primary {alpha} size. The crack growth rates through each phase indicate that the main difference between the rheocast and the squeeze cast material is in the crack propagation across the grain boundaries with the other regions having almost comparable crack propagation rates in the same as well as between different materials. The fact that even decrease in grain size does not lead to the impressive improvement in fatigue strength can not be attributed to the difference in grain structure according to quantitative investigation of misorientation angles between neighboring grains utilizing a scanning electron

  16. Clean Cast Steel Technology, Phase IV

    Energy Technology Data Exchange (ETDEWEB)

    Charles E. Bates

    2003-02-24

    The objective of the Clean Cast Steel Technology Program was to improve casting product quality by removing or minimizing oxide defects and to allow the production of higher integrity castings for high speed machining lines. Previous research has concentrated on macro-inclusions that break, chip, or crack machine tool cutters and drills and cause immediate shutdown of the machining lines. The overall goal of the project is to reduce the amount of surface macro-inclusions and improve the machinability of steel castings. Macro-inclusions and improve the machinability of steel castings. Macro-inclusions have been identified by industrial sponsors as a major barrier to improving the quality and marketability of steel castings.

  17. Homogenity of Die Casting and Returning Material

    Directory of Open Access Journals (Sweden)

    J. Malik

    2012-04-01

    Full Text Available Homogeneity of die castings is influenced by wide range of technological parameters as piston velocity in filling chamber of die casting machine, filling time of mould cavity, temperature of cast alloy, temperature of the mould, temperature of filling chamber, surface pressure on alloy during mould filling, final pressure and others. Based on stated parameters it is clear, that main parameters of die casting are filling time of die mould cavity and velocity of the melt in the ingates. Filling time must ensure the complete filling of the mould cavity before solidification process can negatively influence it. Among technological parameters also belong the returning material, which ratio in charge must be constrained according to requirement on final homogeneity of die castings. With the ratio of returning material influenced are the mechanical properties of castings, inner homogeneity and chemical composition.

  18. Advanced casting technologies for lightweight automotive applications

    Directory of Open Access Journals (Sweden)

    Alan A. Luo

    2010-11-01

    Full Text Available This paper provides an overview of alloy and process developments in aluminum and magnesium castings for lightweight automotive applications. Wear-resistant aluminum alloys, creep-resistant and high strength/ductility magnesium alloys have been developed for automotive applications. On the process front, vacuum-assisted die casting and high vacuum die casting technologies have been developed for high-integrity body and chassis applications. Thin-wall and hollow casting components are being produced by low-pressure die casting processes for structural applications. Overcasting technology is gaining traction and has enabled mixed material designs for automotive sub-systems such as engine cradles and instrument panel beams. Simulation tools developed to predict the interfacial interactions of the dissimilar components and the structural integrity of the overcast systems are being validated in the casting trials.

  19. Chilling Tendency and Chill of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    E. Fra(s); M. Górny; W. Kapturkiewicz; H. López

    2008-01-01

    An analytical expression is presented for the susceptibility of liquid cast iron to solidify according tothe Fe-C-X metastable system (also known as the chilling tendency of cast iron, CT). The analysis incorpo-rates the nucleation and growth processes associated with the eutectic transformation. The CT is related tothe physicochemical state of the liquid, the eutectic cells in the flake graphite, and the number of nodules innodular cast iron. In particular, the CT can be related to the critical wall thickness, Scr, or the chill width, Wcr,in wedge shaped castings. Finally, this work serves as a guide for understanding the effect of technical fac-tors such as the melt chemistry, the spheroidizing and inoculation practice, and the holding time and tam-perature on the resultant CT and chill of the cast iron. Theoretical calculations of Scr and Wcr compare wellwith experimental data for flake graphite and nodular cast iron.

  20. Method for casting thin metal objects

    Energy Technology Data Exchange (ETDEWEB)

    Pehrson, Brandon P; Moore, Alan F

    2015-04-14

    Provided herein are various embodiments of systems for casting thin metal plates and sheets. Typical embodiments include layers of mold cavities that are oriented vertically for casting the metal plates. In some embodiments, the mold cavities include a beveled edge such that the plates that are cast have a beveled edge. In some embodiments, the mold cavities are filled with a molten metal through an open horizontal edge of the cavity. In some embodiments, the mold cavities are filled through one or more vertical feed orifices. Further disclosed are methods for forming a thin cast metal plate or sheet where the thickness of the cast part is in a range from 0.005 inches to 0.2 inches, and the surface area of the cast part is in a range from 16 square inches to 144 square inches.