Science.gov

Sample records for age hardening behavior

  1. Hydrogen effects on the age hardening behavior of 2024 aluminum

    NASA Technical Reports Server (NTRS)

    Wagner, J. A.; Louthan, M. R., Jr.; Sisson, R. D., Jr.

    1986-01-01

    It has been found that the fatigue crack growth rate in aluminum alloys increases significantly in the presence of moisture. This phenomenon along with a moisture effect observed in another context has been attributed to 'embrittlement' of the aluminum by absorbed hydrogen generated by the reaction of moisture with freshly exposed aluminum. A description is given of a number of age hardening experiments involving 2024 aluminum. These experiments show that a mechanism related to the segregation of absorbed hydrogen to the coherent theta-double-prime interfaces may account for the observed reduction in fatigue life. It is pointed out that this segregation promotes a loss of coherency in the hydrogen rich region at a fatigue crack tip. Subsequently, the loss of coherency causes local softening and reduces fatigue life.

  2. Microstructural evolution and the variation of tensile behavior after aging heat treatment of precipitation hardened martensitic steel

    SciTech Connect

    Shin, Jong-Ho; Jeong, JaeSuk; Lee, Jong-Wook

    2015-01-15

    The effects of aging temperature on the microstructural evolution and the tensile behavior of precipitation hardened martensitic steel were investigated. Microscopic analysis using transmission electron microscope (TEM) was combined with the microstructural analysis using the synchrotron X-ray diffraction (XRD) to characterize the microstructural evolution with aging temperature. Peak hardness was obtained by precipitation of the Ni{sub 3}Al ordered phase. After aging at temperature range from 420 to 590 °C, spherical Ni{sub 3}Al precipitates and ellipsoidal M{sub 23}C{sub 6} carbides were observed within laths and at lath boundaries, respectively. Strain hardening behavior was analyzed with Ludwik equation. It is observed that the plastic strain regimes can be divided into two different stages by a rapid increase in strain hardening followed by a comparatively lower increase. At the first strain hardening stage, the aged specimen exhibited higher strain hardening exponent than the as-quenched specimen, and the exponent in the aged specimen was not changed considerably with increasing aging temperature. It is revealed that the strain hardening exponents at the first and the second stages were associated with the Ni{sub 3}Al precipitates and the domain size representing the coherent scattering area, respectively. - Highlights: • All of aged specimen exhibited higher strain hardening exponent than the as-quenched specimen at the first stage. • The value of strain hardening exponent in the aged specimen was nearly constant with aging temperature. • Ni{sub 3}Al precipitation dominantly influenced to the increase of strain hardening exponent at the first strain hardening stage. • Domain size was associated with strain hardening exponent at the second strain hardening stage.

  3. Age hardening characteristics and mechanical behavior of Al-Cu-Li-Zr-In alloys

    NASA Technical Reports Server (NTRS)

    Wagner, John A.

    1989-01-01

    An investigation was conducted to determine the age-hardening response and cryogenic mechanical properties of superplastic Al-Cu-Li-Zr-In alloys. Two alloys with compositions Al-2.65Cu-2.17Li-O.13Zr (baseline) and Al-2.60Cu-2.34Li-0.16Zr-0.17In were scaled-up from 30 lb permanent mold ingots to 350 lb DC (direct chill) ingots and thermomechanically processed to 3.2 mm thick sheet. The microstructure of material which contained the indium addition was partially recrystallized compared to the baseline suggesting that indium may influence recrystallization behavior. The indium-modified alloy exhibited superior hardness and strength compared to the baseline alloy when solution-heat-treated at 555 C and aged at 160 C or 190 C. For each alloy, strength increased and toughness was unchanged or decreased when tested at - 185 C compared to ambient temperature. By using optimized heat treatments, the indium-modified alloy exhibited strength levels approaching those of the baseline alloy without deformation prior to aging. The increase in strength of these alloys in the T6 condition make them particularly attractive for superplastic forming applications where post-SPF parts cannot be cold deformed to increase strength.

  4. Age-hardening behaviors and grain boundary discontinuous precipitation in a Pd-free gold alloy for porcelain bonding.

    PubMed

    Shiraishi, Takanobu; Ohta, Michio

    2002-10-01

    Isothermal age-hardening behaviors at 400 degrees and 450 degrees C and discontinuous precipitation reaction at 450 degrees C in a commercial Pd-free gold alloy for porcelain bonding were investigated by hardness testing, X-ray powder diffraction, and light microscopy. Variations of electrical resistivity during continuous heating and cooling processes were also measured. The alloy exhibited pronounced age-hardening in the early stage of aging and the maximum hardness exceeded twice that of the solution-treated sample. Precise lattice parameter measurements and investigations of full width at half maximum values for the X-ray Bragg reflections implied that nonuniform strains due to the pre-precipitation or zone formation was responsible for the quick and pronounced age-hardening at 450 degrees C. Discontinuous precipitation reaction, producing a mixture of a small amount of Pt(3)In-phase with the L1(2)-type superstructure and a large amount of (Pt, In)-depleted solid solution, started at grain boundaries in the late stage of aging process at 450 degrees C. The growth of the grain boundary discontinuous precipitates toward the intragrain area led to a gradual decrease in hardness of the alloy. PMID:15348193

  5. Influence of Thermal Aging on the Microstructure and Mechanical Behavior of Dual-Phase, Precipitation-Hardened, Powder Metallurgy Stainless Steels

    NASA Astrophysics Data System (ADS)

    Stewart, J. L.; Williams, J. J.; Chawla, N.

    2012-01-01

    The effects of thermal aging on the microstructure and mechanical behavior of dual-phase, precipitation-hardened, powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels, and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 811 K (538 °C) in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite nanohardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties.

  6. Comparative study of structure formation and mechanical behavior of age-hardened Ti–Nb–Zr and Ti–Nb–Ta shape memory alloys

    SciTech Connect

    Inaekyan, K.; Brailovski, V.; Prokoshkin, S.; Pushin, V.; Dubinskiy, S.; Sheremetyev, V.

    2015-05-15

    This work sets out to study the peculiar effects of aging treatment on the structure and mechanical behavior of cold-rolled and annealed biomedical Ti–21.8Nb–6.0Zr (TNZ) and Ti–19.7Nb–5.8Ta (TNT) (at.%) shape memory alloys by means of transmission electron microscopy, X-ray diffractometry, functional fatigue and thermomechanical testing techniques. Dissimilar effects of aging treatment on the mechanical behavior of Zr- and Ta-doped alloys are explained by the differences in the ω-phase formation rate, precipitate size, fraction and distribution, and by their effect on the alloys' critical stresses and transformation temperatures. Even short-time aging of the TNZ alloy leads to its drastic embrittlement caused by “overaging”. On the contrary, during aging of the TNT alloy, formation of finely dispersed ω-phase precipitates is gradual and controllable, which makes it possible to finely adjust the TNT alloy functional properties using precipitation hardening mechanisms. To create in this alloy nanosubgrained dislocation substructure containing highly-dispersed coherent nanosized ω-phase precipitates, the following optimum thermomechanical treatment is recommended: cold rolling (true strain 0.37), followed by post-deformation annealing (600 °C, 15–30 min) and age-hardening (300 °C, 30 min) thermal treatments. It is shown that in TNT alloy, pre-transition diffraction effects (diffuse reflections) can “mask” the β-phase substructure and morphology of secondary phases. - Highlights: • TNZ alloy is characterized by much higher ω-phase precipitation rate than TNT alloy. • Difference in precipitation rates is linked to the difference in Zr and Ta diffusion mobility. • Aging of nanosubgrained TNZ alloy worsens its properties irrespective of the aging time. • Aging time of nanosubgrained TNT alloy can be optimized to improve its properties.

  7. Weldable, age hardenable, austenitic stainless steel

    DOEpatents

    Brooks, J.A.; Krenzer, R.W.

    1975-07-22

    An age hardenable, austenitic stainless steel having superior weldability properties as well as resistance to degradation of properties in a hydrogen atmosphere is described. It has a composition of from about 24.0 to about 34.0 weight percent (w/o) nickel, from about 13.5 to about 16.0 w/o chromium, from about 1.9 to about 2.3 w/o titanium, from about 1.0 to about 1.5 w/ o molybdenum, from about 0.01 to about 0.05 w/o carbon, from about 0 to about 0.25 w/o manganese, from about 0 to about 0.01 w/o phosphorous and preferably about 0.005 w/o maximum, from about 0 to about 0.010 w/o sulfur and preferably about 0.005 w/o maximum, from about 0 to about 0.25 w/o silicon, from about 0.1 to about 0.35 w/o aluminum, from about 0.10 to about 0.50 w/o vanadium, from about 0 to about 0.0015 w/o boron, and the balance essentially iron. (auth)

  8. Effect of reinforcing particle type on morphology and age-hardening behavior of Al–4.5 wt.% Cu based nanocomposites synthesized through mechanical milling

    SciTech Connect

    Mostaed, A.; Saghafian, H.; Mostaed, E.; Shokuhfar, A.; Rezaie, H.R.

    2013-02-15

    The effects of reinforcing particle type (SiC and TiC) on morphology and precipitation hardening behavior of Al–4.5%Cu based nanocomposites synthesized via mechanical milling were investigated in the current work. In order to study the microstructure and morphology of mechanically milled powder, X-ray diffraction technique, scanning electron microscopy and high resolution transmission electron microscopy were utilized. Results revealed that at the early stages of mechanical milling, when reinforcing particles are polycrystal, the alloying process is enhanced more in the case of using the TiC particles as reinforcement. But, at the final stages of mechanical milling, when reinforcing particles are single crystal, the alloying process is enhanced more in the case of using the SiC ones. Transmission electron microscopy results demonstrated that Al–4.5 wt.%Cu based nanocomposite powders were synthesized and confirmed that the mutual diffusion of aluminum and copper occurs through the interfacial plane of (200). The hardness results showed that not only does introducing 4 vol.% of reinforcing particles (SiC or TiC) considerably decrease the porosity of the bulk composite samples, but also it approximately doubles the hardness of Al–4.5 wt.%Cu alloy (53.4 HB). Finally, apart from TEM and scanning electron microscopy observation which are localized, a decline in hardness in the TiC and SiC contained samples, respectively, after 1.5 and 2 h aging time at 473 K proves the fact that the size of SiC particles is smaller than the size of the TiC ones. - Highlights: ► HRTEM results show mutual diffusion of Al and Cu occurs through the (200) planes. ► TiC particles enhance alloying process more than the SiC ones at the early stages of MM. ► SiC particles enhance alloying process more than the TiC ones at the final stages of MM.

  9. Continuous Hardening During Isothermal Aging at 723 K (450 °C) of a Precipitation Hardening Stainless Steel

    NASA Astrophysics Data System (ADS)

    Celada-Casero, Carola; Chao, Jesús; Urones-Garrote, Esteban; San Martin, David

    2016-06-01

    The isothermal aging behavior of a cold-rolled precipitation hardening stainless steel has been studied at 723 K (450 °C) for holding times up to 72 hours. The precipitation hardening has been investigated using microhardness Vickers (Hv), thermoelectric power (TEP) measurements, and tensile testing. Microhardness compared to TEP measurements is more sensitive to detect the initial stages of aging. Two precipitation regimes have been observed: the first one related to the formation of Cu-clusters for aging times below 1 hour and a second one associated with formation of Ni-rich precipitates. The results show that the material exhibits an outstanding continuous age strengthening response over the aging time investigated, reaching a hardness of 710 ± 4 HV1 and an ultimate tensile strength (σ UTS) of 2.65 ± 0.02 GPa after 72 hours. Engineering stress-plastic strain curves reveal that the strength increases and the ductility decreases as the aging time increases. However, after prolonged holding times (24-72 hours) and, although small, a rise in both the strength and the total elongation is observed. The precipitation kinetics can be well predicted over the entire range of aging times by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a reliable linear hardness-yield strength correlation has been found, which enables a rapid evaluation of the strength from bulk hardness measurements.

  10. Forming an age hardenable aluminum alloy with intermediate annealing

    NASA Astrophysics Data System (ADS)

    Wang, Kaifeng; Carsley, John E.; Stoughton, Thomas B.; Li, Jingjing; Zhang, Lianhong; He, Baiyan

    2013-12-01

    A method to improve formability of aluminum sheet alloys by a two-stage stamping process with intermediate annealing was developed for a non-age hardenable Al-Mg alloy where the annealing heat treatment provided recovery of cold work from the initial stamping and recrystallization of the microstructure to enhance the forming limits of the material. This method was extended to an age hardenable, Al-Mg-Si alloy, which is complicated by the competing metallurgical effects during heat treatment including recovery (softening effect) vs. precipitation (hardening effect). An annealing heat treatment process condition was discovered wherein the stored strain energy from an initial plastic deformation can be sufficiently recovered to enhance formability in a second deformation; however, there is a deleterious effect on subsequent precipitation hardening. The improvement in formability was quantified with uniaxial tensile tests as well as with the forming limit diagram. Since strain-based forming limit curves (FLC) are sensitive to pre-strain history, both stress-based FLCs and polar-effective-plastic-strain (PEPS) FLCs, which are path-independent, were used to evaluate the forming limits after preform annealing. A technique was developed to calculate the stress-based FLC in which a residual-effective-plastic-strain (REPS) was determined by overlapping the hardening curve of the pre-strained and annealed material with that of the simply-annealed- material. After converting the strain-based FLCs using the constant REPS method, it was found that the stress-based FLCs and the PEPS FLCs of the post-annealed materials were quite similar and both tools are applicable for evaluating the forming limits of Al-Mg-Si alloys for a two-step stamping process with intermediate annealing.

  11. Age hardening of 6061/alumina-silica fiber composite

    SciTech Connect

    Khangaonkar, P.R.; Shamsul, J.B.; Azmi, R.

    1994-12-31

    Continuous alumina-silica fiber (Altex of Sumitomo) which yields high performance composites with some aluminium alloys was tried for squeeze cast 6061 based composites with volume fractions of 0.5 and 0.32, and the matrix microhardness and resistivity changes during age hardening were studied. The matrix in the composites hardened much more than the unreinforced alloy. Microhardness increases of up to 70 VPN above the solution treated condition at various aging temperatures were observed. The resistivity variation indicated an appreciable state of internal stress which continued to persist even when hardness fell by overaging. Energy dispersive X-ray analysis indicated that the regions close to the fibers had a higher silicon content than the matrix, and amorphous silica in the fiber may have a role in the formation of an enriched layer which may help the bonding and strength in the composite.

  12. Description of full-range strain hardening behavior of steels.

    PubMed

    Li, Tao; Zheng, Jinyang; Chen, Zhiwei

    2016-01-01

    Mathematical expression describing plastic behavior of steels allows the execution of parametric studies for many purposes. Various formulas have been developed to characterize stress strain curves of steels. However, most of those formulas failed to describe accurately the strain hardening behavior of steels in the full range which shows various distinct stages. For this purpose, a new formula is developed based on the well-known Ramberg-Osgood formula to describe the full range strain hardening behavior of steels. Test results of all the six types of steels show a three-stage strain hardening behavior. The proposed formula can describe such behavior accurately in the full range using a single expression. The parameters of the formula can be obtained directly and easily through linear regression analysis. Excellent agreements with the test data are observed for all the steels tested. Furthermore, other formulas such as Ludwigson formula, Gardner formula, UGent formula are also applied for comparison. Finally, the proposed formula is considered to have wide suitability and high accuracy for all the steels tested. PMID:27563511

  13. Elastic constant versus temperature behavior of three hardened maraging steels

    NASA Technical Reports Server (NTRS)

    Ledbetter, H. M.; Austin, M. W.

    1985-01-01

    Elastic constants of three maraging steels were determined by measuring ultrasonic velocities. Annealed steels show slightly lower bulk moduli and considerably lower shear moduli than hardened steels. All the elastic constants (Young's modulus, shear modulus, bulk modulus and Poisson's ratio) show regular temperature behavior between 76 and 400 K. Young's modulus and the shear modulus increase with increasing yield strength, but the bulk modulus and Poisson's ratio are relatively unchanged. Elastic anisotropy is quite small.

  14. Magnetic age hardening of cold-deformed bulk equiatomic Fe-Pd intermetallics during isothermal annealing

    NASA Astrophysics Data System (ADS)

    Deshpande, A. R.; Wiezorek, J. M. K.

    2004-03-01

    The interplay between the ordering reaction with recovery and recrystallization of the as-deformed state leads to combined reactions (CRs) during annealing of cold-deformed disordered Fe-Pd intermetallics at temperatures below the critical ordering temperature. CRs can be exploited to control the scale and morphology of the Fe-Pd alloy microstructures in order to optimize alloy properties. Here, the magnetic age hardening behavior and microstructural evolution of cold-deformed (cold rolled to 97% reduction in thickness) binary equiatomic Fe-Pd has been studied for isothermal annealing at temperatures of 400°C, 500°C, and 600°C. The evolution of the microstructure during the annealing treatments has been characterized by a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic age hardening behavior, the evolution of the coercivity as a function of annealing time, has been determined using a vibrating sample magnetometer (VSM). The microstructures of the transforming material have been characterized quantitatively using computer assisted image analysis methods. The CR transformed microstructures are morphologically equiaxed with average grain sizes in the sub-micron range and show coercivity up to five-fold larger than for conventionally processed equiatomic bulk Fe-Pd. During annealing the coercivity increases up to a maximum peak value and has been correlated with the increasing fraction of ordered material. The maximum coercivity obtains, as the ordering phase transformation is complete. With respect to conventionally processed material the ordering transformation in the cold-deformed material exhibits accelerated kinetics and is facilitated by a CR, which involves heterogeneous nucleation and growth processes akin to a 'massive ordering' reaction. Further annealing leads to decreasing coercivity, which has been attributed to the onset of grain growth in the population of CR-transformed grains. The characteristic magnetic

  15. 'Age-hardened alloy' based on bulk polycrystalline oxide ceramic

    NASA Astrophysics Data System (ADS)

    Gurnani, Luv; Singh, Mahesh Kumar; Bhargava, Parag; Mukhopadhyay, Amartya

    2015-05-01

    We report here for the first time the development of 'age-hardened/toughened' ceramic alloy based on MgO in the bulk polycrystalline form. This route allows for the facile development of a 'near-ideal' microstructure characterized by the presence of nanosized and uniformly dispersed second-phase particles (MgFe2O4) within the matrix grains, as well as along the matrix grain boundaries, in a controlled manner. Furthermore, the intragranular second-phase particles are rendered coherent with the matrix (MgO). Development of such microstructural features for two-phase bulk polycrystalline ceramics is extremely challenging following the powder metallurgical route usually adopted for the development of bulk ceramic nanocomposites. Furthermore, unlike for the case of ceramic nanocomposites, the route adopted here does not necessitate the usage of nano-powder, pressure/electric field-assisted sintering techniques and inert/reducing atmosphere. The as-developed bulk polycrystalline MgO-MgFe2O4 alloys possess considerably improved hardness (by ~52%) and indentation toughness (by ~35%), as compared to phase pure MgO.

  16. Effect of Al Addition on ω Precipitation and Age Hardening of Ti-Al-Mo-Fe Alloys

    NASA Astrophysics Data System (ADS)

    Li, Chenglin; Lee, Dong-Geun; Mi, Xujun; Ye, Wenjun; Hui, Songxiao; Lee, Yongtai

    2016-05-01

    The effect of Al addition on ω precipitation and age-hardening behavior of Ti-9.2Mo-2Fe and Ti-2Al-9.2Mo-2Fe alloy during aging treatment was investigated. The results showed that athermal and isothermal ω phase formation in Ti-2Al-9.2Mo-2Fe alloy was suppressed to a certain extent due to Al addition. In addition, a small amount of athermal ω phase was observed in the β matrix with a size of about ~5 nm during water quenching from above the β transus temperature for both alloys. Isothermal ω formation was also found during aging at temperatures ranging from 573 K to 773 K (300 °C to 500 °C) in both alloys, although it had a limited time of stability at 773 K (500 °C). The hardening due to isothermal ω precipitation exhibited no over-aging as long as ω phase existed in both alloys, and ω phase played a more important role in hardening than α phase. And the ω phase in 50 to 100 nm size exhibited the best hardening effect in Ti-9.2Mo-2Fe alloy. Similarly, α phase with 100 to 200 nm in length showed better hardening effects in Ti-2Al-9.2Mo-2Fe alloy. Both the alloys showed stronger age hardening at an intermediate temperature of 673 K (400 °C) and in the first aging stage at a higher temperature of 773 K (500 °C) due to the sufficiently fine size (50 nm), while they exhibited weaker age hardening at a lower temperature of 573 K (300 °C) and long period aging at a higher temperature of 773 K (500 °C) due to incomplete ω formation and/or coarsening of α phase. No over or peak aging stage was found at 573 K and 673 K (300 °C and 400 °C) during the aging for 72 hours, while the peak hardness values of both alloys aged at 773 K (500 °C) were obtained in the first stage of aging. The hardness of the alloys was very sensitive to size and volume fraction of ω phase, which depends on aging temperature, time, and composition of the involved alloys.

  17. Effects of Ce additions on the age hardening response of Mg–Zn alloys

    SciTech Connect

    Langelier, Brian Esmaeili, Shahrzad

    2015-03-15

    The effects of Ce additions on the precipitation hardening behaviour of Mg–Zn are examined for a series of alloys, with Ce additions at both alloying and microalloying levels. The alloys are artificially aged, and studied using hardness measurement and X-ray diffraction, as well as optical and transmission electron microscopy. It is found that the age-hardening effect is driven by the formation of fine precipitates, the number density of which is related to the Zn content of the alloy. Conversely, the Ce content is found to slightly reduce hardening. When the alloy content of Ce is high, large secondary phase particles containing both Ce and Zn are present, and remain stable during solutionizing. These particles effectively reduce the amount of Zn available as solute for precipitation, and thereby reduce hardening. Combining hardness results with thermodynamic analysis of alloy solute levels also suggests that Ce can have a negative effect on hardening when present as solutes at the onset of ageing. This effect is confirmed by designing a pre-ageing heat treatment to preferentially remove Ce solutes, which is found to restore the hardening capability of an Mg–Zn–Ce alloy to the level of the Ce-free alloy. - Highlights: • The effects of Ce additions on precipitation in Mg–Zn alloys are examined. • Additions of Ce to Mg–Zn slightly reduce the age-hardening response. • Ce-rich secondary phase particles deplete the matrix of Zn solute. • Hardening is also decreased when Ce is present in solution. • Pre-ageing to preferentially precipitate out Ce restores hardening capabilities.

  18. Precipitation hardening and microstructure evolution of the Ti-7Nb-10Mo alloy during aging.

    PubMed

    Yi, Ruowei; Liu, Huiqun; Yi, Danqing; Wan, Weifeng; Wang, Bin; Jiang, Yong; Yang, Qi; Wang, Dingchun; Gao, Qi; Xu, Yanfei; Tang, Qian

    2016-06-01

    A biomedical β titanium alloy (Ti-7Nb-10Mo) was designed and prepared by vacuum arc self-consumable melting. The ingot was forged and rolled to plates, followed by quenching and aging. Age-hardening behavior, microstructure evolution and its influence on mechanical properties of the alloy during aging were investigated, using X-ray diffraction, transmission electron microscopy, tensile and hardness measurements. The electrochemical behavior of the alloy was investigated in Ringer's solution. The microstructure of solution-treated (ST) alloy consists of the supersaturated solid solution β phase and the ωath formed during athermal process. The ST alloy exhibits Young's modulus of 80 GPa, tensile strength of 774 MPa and elongation of 20%. The precipitation sequences during isothermal aging at different temperatures were determined as β+ωath→β+ωiso (144 h) at Taging=350-400 °C, β+ωath→β+ωiso+α→β+α at Taging=500°C, and β+ωath→β+α at Taging=600-650 °C, where ωiso forms during isothermal process. The mechanical properties of the alloy can be tailored easily through controlling the phase transition during aging. Comparing with the conventional Ti-6Al-4V alloy, the Ti-7Nb-10Mo alloy is more resistant to corrosion in Ringer's solution. Results show that the Ti-7Nb-10Mo alloy is promising for biomedical applications. PMID:27040253

  19. Phase decomposition in an Fe-40 at.% Cr alloy after isothermal aging and its effect on hardening

    SciTech Connect

    Lopez-Hirata, Victor M. Soriano-Vargas, Orlando; Rosales-Dorantes, Hector J.; Saucedo Munoz, Maribel L.

    2011-08-15

    The phase decomposition process of an Fe-40 at.% Cr alloy was studied after isothermal aging at 475 and 500 deg. C using a high-resolution transmission electron microscope, as well as hardness measurements. High-resolution transmission electron microscope observations showed that the hardening behavior is associated with the formation of the nanometric coherent decomposed Cr-rich and Fe-rich phases with irregular shape and interconnected as expected for a spinodally-decomposed alloy. As the aging progressed, coherent rounded Cr-rich phase precipitates were observed in the Fe-rich phase matrix. The coarsening process of the Cr-rich phase was observed for aging times up to 750 h. Nevertheless, no decrease in hardness with time was observed because of the nanometric size of the Cr-rich phase, less than 10 nm. Aging hardening was higher at 500 deg. C because of the higher decomposition kinetics. - Research Highlights: {yields} Spinodally-decomposed phases showed an interconnected and irregular shape in aged Fe-Cr alloy. {yields} Further aging promoted the formation of nanometric coherent rounded Cr-rich precipitates. {yields} Nanometric Cr-rich phases are responsible for the age hardening. {yields} Coarsening process of these nanometric Cr-rich precipitates caused no decrease in hardness.

  20. Precipitation Reactions in Age-Hardenable Alloys During Laser Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Jägle, Eric A.; Sheng, Zhendong; Wu, Liang; Lu, Lin; Risse, Jeroen; Weisheit, Andreas; Raabe, Dierk

    2016-03-01

    We describe and study the thermal profiles experienced by various age-hardenable alloys during laser additive manufacturing (LAM), employing two different manufacturing techniques: selective laser melting and laser metal deposition. Using scanning electron microscopy and atom probe tomography, we reveal at which stages during the manufacturing process desired and undesired precipitation reactions can occur in age-hardenable alloys. Using examples from a maraging steel, a nickel-base superalloy and a scandium-containing aluminium alloy, we demonstrate that precipitation can already occur during the production of the powders used as starting material, during the deposition of material (i.e. during solidification and subsequent cooling), during the intrinsic heat treatment effected by LAM (i.e. in the heat affected zones) and, naturally, during an ageing post-heat treatment. These examples demonstrate the importance of understanding and controlling the thermal profile during the entire additive manufacturing cycle of age-hardenable materials including powder synthesis.

  1. Quantification of age hardening in maraging steels and an Ni-base superalloy

    SciTech Connect

    Sha, W.

    2000-02-01

    Age hardening process in metallic alloys due to precipitation can be quantified using phase transformation theories. Two ageing stages are of particular interest, for both theory and practice. The early stage of precipitation hardening is under the description of the Johnson-Mehl-Avrami equation. Wilson has recently provided a detailed theoretical analysis for early stages of ageing. Wilson successfully used equations in the quantification of early and over-ageing stages of hardening in an Fe-12Ni-6Mn maraging-type alloy. In the present work, these were applied to further alloys. All the hardness data were taken from published literature. Original references should be consulted for details of materials, testing and characterization.

  2. Isothermal age-hardening behaviour in a Au-1.6 wt% Ti alloy.

    PubMed

    Kim, H I; Seol, H J; Bae, D H; Shim, J Y; Takada, Y; Okuno, O

    1999-03-01

    This study describes research with a view to developing a new age-hardenable, high-carat dental gold alloy with better biocompatibility by addition of a small quantity of titanium to gold. The relationship between isothermal age-hardening and phase transformation of the Au-1.6 wt% Ti alloy was investigated by means of hardness testing, X-ray diffraction study, scanning electron microscopic observation and energy dispersive spectroscopy. The hardening in the initial stage of ageing seemed to be attributable to the continuous precipitation of the Au4Ti ordered phase in the supersaturated alpha solid solution matrix. The overaging with softening was attributed mainly to the formation of precipitates at the grain boundaries, which grew to bright lamellae and seemed to be composed of the Au4Ti phase. PMID:10786146

  3. Age Hardening Kinetics in 7xxx Type (Al-Mg-Zn) Alloys

    SciTech Connect

    Vevecka-Priftaj, A.; Lamani, E.; Fjerdingen, J.; Langsrud, Y.; Gjoennes, J.; Hansen, V.

    2007-04-23

    Age hardening in industrial 7xxx alloys at the temperature 100 deg. and 150 deg. C up to 144 hrs, after solid solution treatments at 450 deg. and 550 deg. C, has been followed by measurements of Vickers hardness, scanning and transmission electron microscopy. The influence of silicon on phase and kinetic of age hardening zones and precipitates has been studied. High iron and silicon content increase the number of primary particle in the alloy. Size distribution of {eta}'-precipitates has been determined.

  4. Modifications of the Response of Materials to Shock Loading by Age Hardening

    NASA Astrophysics Data System (ADS)

    Millett, Jeremy C. F.

    2015-10-01

    The shock response of two age-hardened alloys, aluminum 6061 and copper-2 wt pct beryllium (CuBe), has been investigated in terms of their microstructual state; either solution treated or age hardened. While age hardening induces large increases in strength at quasi-static strain rates, age hardening does not produce the same magnitude of strength increase during shock loading. Examination of the shocked microstructures (of 6061) indicates that the presence of a fine distribution of precipitates throughout the microstructure hinders the motion and generation of dislocations and hence reduces the strain-rate sensitivity of the aged material, thus allowing the properties of the solution-treated state to approach those of the aged. It has also been observed that the shear strength of solution-treated CuBe is near identical to that of pure copper. It is suggested that this is the result of two competing processes; large lattice strains as beryllium substitutes onto the copper lattice inducing a high degree of solution strengthening acting against a reduction in shear strength caused by twinning in the alloy.

  5. Tensile flow and work-hardening behavior of a Ti-modified austenitic stainless steel

    SciTech Connect

    Sivaprasad, P.V.; Venugopal, S.; Venkadesan, S.

    1997-01-01

    The flow-stress data of a 15Cr-15Ni-2.2Mo-Ti modified austenitic stainless steel in the temperature range 300 to 1,023 K was analyzed in terms of Ludwigson and Voce equations. The parameters of these equations were critically examined with respect to the effect of Ti/C ratio and test temperature. It was found that the Ludwigson equation described the flow behavior adequately up to the test temperature of 923 K, whereas the Voce equation could be employed in the full temperature range. The peaks/plateaus observed in the variation of these parameters as a function of temperature in the intermediate temperature range have been identified as one of the manifestations of dynamic strain aging (DSA). Also, the variation of these parameters with temperature clearly could bring out the different domains of DSA observed in this alloy. The work-hardening analysis of the flow-stress data revealed that in the DSA regime, the onset of stage III hardening is athermal.

  6. Structural influences on the work hardening behavior of aluminum

    SciTech Connect

    Chu, D.

    1994-12-01

    Effects of various grain and subgrain morphologies on low temperature work hardening of pure Al is studied using tensile tests. Plotting the work hardening rate as a function of true stress, the work hardening is separable into two distinct regimes. Both regimes are approximated by a line {Theta} = {Theta}{sub 0} {minus} K{sub 2}{sigma}, where {Theta}{sub 0} is theoretical work hardening rate at zero stress and K{sub 2} is related to dynamic recovery rate. The first or early deformation regime exhibits greater values of {Theta}{sub 0} and K{sub 2} and can extend up to the first 10% strain of tensile deformation. This early deformation regime is contingent on the existence of a pre-existent dislocation substructure from previous straining. The {Theta}{sub 0} and K{sub 2} associated with the early deformation regime are dependent on the strength and orientation of the pre-existent dislocation substructure relative to the new strain path. At high enough temperatures, this pre-existent dislocation substructure is annealed out, resulting in the near elimination of the early deformation regime. In comparison, the latter regime is dominated by the initial grain and/or subgrain morphology and exhibit lower values of {Theta}{sub 0} and K{sub 2}. The actual value of K{sub 2} in the latter regime is strongly dependent on the existence of a subgrain morphology. Recrystallized or well-annealed microstructures exhibit greater values of K{sub 2} than microstructures that remain partially or fully unrecrystallized. The higher K{sub 2} value is indicative of a more rapid dynamic recovery rate and a greater degree of strain relaxation. The ability to achieve a more relaxed state produces a low-energy cellular dislocation substructure upon deformation. The introduction of subgrains hinders the evolution of a low-energy dislocation cell network, giving way to a more random distribution of the dislocation density.

  7. YIELD STRENGTH PREDICTION FOR RAPID AGE-HARDENING HEAT TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Ludtka, Gerard Michael; Skszek, Timothy; Niu, X

    2013-01-01

    A constitutive model has been developed to predict the yield strength aging curves for aluminum casting alloys during non-isothermal age-hardening processes. The model provides the specific relationship between the process variables and yield strength. Several aging heat treatment scenarios have been investigated using the proposed model, including two-step aging recipes. Two-step aging heat treatments involve a low temperature regime to promote nucleation of secondary phases and a second step at higher temperature for the growth of the secondary phases. The predicted results show that yield strength of approximately 300MPa might be obtained in shorter aging time, of approximately 30 minutes. Thus, better mechanical properties can be obtained by optimizing the time-temperature schedules for the precipitation hardening process of heat treatable aluminum alloys.

  8. Methodology for the evaluation of yield strength and hardening behavior of metallic materials by indentation with spherical tip

    NASA Astrophysics Data System (ADS)

    Ma, Dejun; Ong, Chung Wo; Lu, Jian; He, Jiawen

    2003-07-01

    This article presents a methodology for evaluating the yield strength and hardening behavior of metallic materials by spherical indentation. Two types of assumed material behaviors with a pure elastic-Hollomon's power law hardening and a pure elastic-linear hardening were considered separately in the models of spherical indentation. The numerical relationships between the material properties and indentation responses were established on the basis of dimensional and finite element analysis. As the first approximation to the real plastic flow properties, the yield strengths and hardening behaviors determined from the spherical indentation loading curve and the numerical relationships were used to derive the intersecting points between Hollomon's power law hardening curve and linear hardening line. Through proceeding the three parameter's regression analysis with Swift's power law function for the intersecting points determined at different maximum indentation depths, the final yield strength and hardening behavior of tested material can be obtained. The validation of this method was examined by investigating three groups of materials with near linear hardening behavior, near Hollomon's power law hardening behavior, and initial yield plateau. It is concluded that the proposed method is applicable to a wide variety of materials which exhibit separate hardening behaviors.

  9. Age-hardening associated with grain boundary precipitation in a commercial dental gold alloy.

    PubMed

    Kim, H I; Jang, M I; Kim, M S

    1999-03-01

    The aim of this study was to make clear the age-hardening mechanism in a dental high carat gold alloy. For this purpose, age-hardening behaviour of a commercial dental high carat gold alloy, 65.5 wt% Au-14.0 wt% Ag-10.0 wt% Cu-8.9 wt% Pt, was investigated by means of hardness testing, X-ray diffraction study and scanning electron microscopy. Age-hardening was generated by the coherency strain resulting from the transformation of the alpha single phase to the Ag-rich alpha 1 phase and the AuCu I type ordered phase. The coherency strain seemed to be associated with the nucleation of the AuCu ordered structure initially, and then was brought about with the simultaneous formation of the Ag-rich alpha 1 phase and the AuCu I type ordered phase. Hardening was attributed mainly to the very fine coherent precipitates of a lamellar structure composed of the Ag-rich alpha 1 phase and the AuCu I type ordered phase at grain boundaries, and softening, which occurred following prolonged ageing, was due to the coarsening of the fine lamellar structure by releasing the strain at the interfaces of the adjacent lamellae. PMID:10194730

  10. Characteristics of laser beam welds of age-hardenable 6061-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.

    2003-03-01

    Laser beam welding is attractive for joining age-hardenable aluminum alloys, because its low over-all heat input results in a narrow weld heat affected zone (HAZ), where softening caused by dissolution of age precipitates occurs. In the present work, 1mm-thick 6061-T6 aluminum alloy plates were welded using a 2.5 kW CO2 laser and it was experimentally proved that the width of the softened region in the laser beam weld was less than 1/7 that of a TIG weld. Moreover the hardness in the softened region of the laser beam weld was found to be almost fully recovered to the base metal hardness by applying a post-weld aging treatment at 443 K for 28.8 ks without solution annealing unlike the TIG weld. These results characterize the advantage of laser beam welding in joining of the age-hardenable aluminum alloy as compared with the conventional arc welding. The hardness distributions in the HAZ were theoretically evaluated based on kinetic equations describing the dissolution of hardening β' (Mg2Si) precipitates and the precipitation of non-hardening β' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  11. Hardening of aged duplex stainless steels by spinodal decomposition.

    PubMed

    Danoix, F; Auger, P; Blavette, D

    2004-06-01

    Mechanical properties, such as hardness and impact toughness, of ferrite-containing stainless steels are greatly affected by long-term aging at intermediate temperatures. It is known that the alpha-alpha' spinodal decomposition occurring in the iron-chromium-based ferrite is responsible for this aging susceptibility. This decomposition can be characterized unambiguously by atom probe analysis, allowing comparison both with the existing theories of spinodal decomposition and the evolution of some mechanical properties. It is then possible to predict the evolution of hardness of industrial components during service, based on the detailed knowledge of the involved aging process. PMID:15233853

  12. Age hardening and creep resistance of cast Al–Cu alloy modified by praseodymium

    SciTech Connect

    Bai, Zhihao; Qiu, Feng; Wu, Xiaoxue; Liu, Yingying; Jiang, Qichuan

    2013-12-15

    The effects of praseodymium on age hardening behavior and creep resistance of cast Al–Cu alloy were investigated. The results indicated that praseodymium facilitated the formation of the θ′ precipitates during the age process and improved the hardness of the Al–Cu alloy. Besides, praseodymium resulted in the formation of the Al{sub 11}Pr{sub 3} phase in the grain boundaries and among the dendrites of the modified alloy. Because of the good thermal stability of Al{sub 11}Pr{sub 3} phase, it inhibits grain boundary migration and dislocation movement during the creep process, which contributes to the improvement in the creep resistance of the modified alloy at elevated temperatures. - Highlights: • Pr addition enhances the hardness and creep resistance of the Al–Cu alloy. • Pr addition facilitates the formation of the θ′ precipitates. • Pr addition results in the formation of the Al11Pr3 phase in the Al–Cu alloy.

  13. Theoretical Study of the Oxidation Behavior of Precipitation Hardening Steel

    SciTech Connect

    Pistofidis, N.; Vourlias, G.; Chrissafis, K.; Psyllaki, P.

    2010-01-21

    The oxidation of precipitation hardening (PH) steels is a rather unexplored area. In the present work an attempt is made is made to estimate the kinetics of a PH steel. For this purpose specimens of the material under examination were isothermally heated at 850, 900 and 950 deg. C for 15 hr. Kinetics was based on TGA results. During heating a thick scale is formed on the substrate surface, which is composed by different oxides. The layer close to the substrate is compact and as a result it impedes corrosion. The mathematical analysis of the collected data shows that the change of the mass of the substrate per unit area versus time is described by a parabolic law.

  14. The Strain-Hardening Behavior of TZAV-30 Alloy After Various Heat Treatments

    NASA Astrophysics Data System (ADS)

    Liang, S. X.; Yin, L. X.; Zheng, L. Y.; Ma, M. Z.; Liu, R. P.

    2016-02-01

    The Ti-Zr-Al-V series titanium alloys with excellent mechanical properties and low density exhibit tremendous application potential as structural materials in aviation, automotive, and navigation industries. The strain-hardening behavior of Ti-30Zr-5Al-3V (wt.%, TZAV-30) alloy with various heat treatments is investigated in this study. Experimental results show that strain-hardening behavior of the examined alloy depends on the heat treatment process. The average strain-hardening exponent, n, is approximately 0.061 for WA specimen (825 °C/0.5 h/water quenching + 600 °C/4 h/air cooling), 0.068 for FC (850 °C/0.5 h/furnace cooling), 0.121 for AC (850 °C/0.5 h/air cooling), and 0.412 for WQ (850 °C/0.5 h/water quenching). Analysis of strain-hardening rate versus true strain curves indicates that higher n of AC specimen results from the lower degradation rate of strain-hardening rate with strain, and the ultrahigh n of WQ specimen is attributed to the evident increase in strain-hardening rate at the true strain from 0.04 to 0.06. Phase constitution and microstructural analyses reveal that the n of the examined alloy with α + β phases increases with the increase in the relative content of the retained β phase but is independent of average thickness of α plates. The increase in strain-hardening rate in WQ specimen depends on metastable α″ martensite and martensitic transition induced by tensile stress.

  15. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    PubMed Central

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-01-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

  16. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths.

    PubMed

    Jiao, Z B; Luan, J H; Miller, M K; Yu, C Y; Liu, C T

    2016-01-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

  17. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    NASA Astrophysics Data System (ADS)

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-02-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.

  18. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    DOE PAGESBeta

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-02-19

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for twomore » interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. Lastly, the co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications.« less

  19. Effects of alloying on aging and hardening processes of steel with 20% nickel

    NASA Technical Reports Server (NTRS)

    Bogachev, I. N.; Zvigintsev, N. V.; Maslakova, T. M.

    1981-01-01

    Measurements of hardness, thermal emf, and electrical resistance were used to study the effects of Co, Mo, Ti and Al contents on aging and hardening processes in Fe 20%Ni steel. It is shown that the effects of these alloying elements differ substantially. Anomalies which arise in the temperature dependence of physical properties due to the presence of cobalt and molybdenum are reduced by the inclusion of titanium and aluminum (and vice versa).

  20. Identifying Deformation and Strain Hardening Behaviors of Nanoscale Metallic Multilayers Through Nano-wear Testing

    DOE PAGESBeta

    Economy, David Ross; Mara, Nathan A.; Schoeppner, R.; Schultz, Bradley M.; Unocic, Raymond R.; Kennedy, Marian S.

    2016-01-13

    In complex loading conditions (e.g. sliding contact), mechanical properties, such as strain hardening and initial hardness, will dictate the long-term performance of materials systems. With this in mind, the strain hardening behaviors of Cu/Nb nanoscale metallic multilayer systems were examined by performing nanoindentation tests within nanoscratch wear boxes and undeformed, as-deposited regions. Both the architecture and substrate influence were examined by utilizing three different individual layer thicknesses (2, 20, and 100 nm) and two total film thicknesses (1 and 10 μm). After nano-wear deformation, multilayer systems with thinner layers showed less volume loss as measured by laser scanning microscopy. Additionally,more » the hardness of the deformed regions significantly rose with respect to the as-deposited measurements, which further increased with greater wear loads. Strain hardening exponents for multilayers with thinner layers (2 and 20 nm, n ≈ 0.018 and n ≈ 0.022 respectively) were less than was determined for 100 nm systems (n ≈ 0.041). These results suggest that singledislocation based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This conclusion indicates that impacts of both architecture strengthening and strain hardening must be considered to accurately predict multilayer performance during sliding contact across varying length scales.« less

  1. Identifying Deformation and Strain Hardening Behaviors of Nanoscale Metallic Multilayers Through Nano-wear Testing

    NASA Astrophysics Data System (ADS)

    Economy, D. Ross; Mara, N. A.; Schoeppner, R. L.; Schultz, B. M.; Unocic, R. R.; Kennedy, M. S.

    2016-03-01

    In complex loading conditions ( e.g., sliding contact), mechanical properties, such as strain hardening and initial hardness, will dictate the long-term performance of materials systems. With this in mind, the strain hardening behaviors of Cu/Nb nanoscale metallic multilayer systems were examined by performing nanoindentation tests within nanoscratch wear boxes and undeformed regions (as-deposited). Both the architecture and substrate influence were examined by utilizing three different individual layer thicknesses (2, 20, and 100 nm) and two total film thicknesses (1 and 10 µm). After nano-wear deformation, multilayer systems with thinner layers showed less volume loss as measured by laser scanning microscopy. Additionally, the hardness of the deformed regions significantly rose with respect to the as-deposited measurements, which further increased with greater wear loads. Strain hardening exponents for multilayers with thinner layers (2 and 20 nm, n ≈ 0.018 and n ≈ 0.022, respectively) were less than that determined for 100 nm systems ( n ≈ 0.041). These results suggest that single-dislocation-based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This conclusion indicates that impacts of both architecture strengthening and strain hardening must be considered to accurately predict multilayer performance during sliding contact across varying length scales.

  2. Effects of age hardening on magnetic and transport properties of Mg-1.3 wt% Ce alloys

    SciTech Connect

    Yamashita, T.; Cavallaro, P.; Kelly, P.M.; Hisa, M.

    1998-05-22

    Magnesium is the lightest structural metal. It has advantages over many other materials in terms of specific strength, machinability and shock absorption. Improvements in magnesium alloy design and more stringent requirements to reduce fuel consumption and air pollution, have recently focused attention on the use of magnesium alloys for automotive components. Here, a Mg-1.3 wt% Ce alloy has been isothermally heat treated at 423 K and the transport and magnetic properties are investigated. This alloy is known to have distinct age hardening behavior and its age hardened microstructure has been studied in detail. The transport properties depend on the early stage of precipitation which is difficult to define by transmission electron microscopy. The scattering sites of electrons are not identical to precipitates, but consist of strain fields induced by the precipitates, solute atoms, dislocations and vacancies. The resistivity was found to increase initially with aging time and then decrease. The highest resistivity was obtained from a specimen aged for 3.6 ks. This aging time is far less than that of 1,800 ks which gives the maximum hardness. On the other hand, magnetic properties correlate with the later stages of the precipitation. In particular, the imaginary part of the magnetic susceptibility is related to macroscopic formation of precipitates. The imaginary part of the magnetic susceptibility of the alloys seems to be generated by eddy current loss. The imaginary part of the magnetic susceptibility increases monotonically with aging time but it may decrease for extensive aging treatments beyond 3,600 ks.

  3. Deformation behavior in reactor pressure vessel steels as a clue to understanding irradiation hardening.

    SciTech Connect

    DiMelfi, R. J.; Alexander, D. E.; Rehn, L. E.

    1999-10-25

    In this paper, we examine the post-yield true stress vs true strain behavior of irradiated pressure vessel steels and iron-based alloys to reveal differences in strain-hardening behavior associated with different irradiating particles (neutrons and electrons) and different alloy chernky. It is important to understand the effects on mechanical properties caused by displacement producing radiation of nuclear reactor pressure steels. Critical embrittling effects, e.g. increases in the ductile-to-brittle-transition-temperature, are associated with irradiation-induced increases in yield strength. In addition, fatigue-life and loading-rate effects on fracture can be related to the post-irradiation strain-hardening behavior of the steels. All of these properties affect the expected service life of nuclear reactor pressure vessels. We address the characteristics of two general strengthening effects that we believe are relevant to the differing defect cluster characters produced by neutrons and electrons in four different alloys: two pressure vessel steels, A212B and A350, and two binary alloys, Fe-0.28 wt%Cu and Fe-0.74 wt%Ni. Our results show that there are differences in the post-irradiation mechanical behavior for the two kinds of irradiation and that the differences are related both to differences in damage produced and alloy chemistry. We find that while electron and neutron irradiations (at T {le} 60 C) of pressure vessel steels and binary iron-based model alloys produce similar increases in yield strength for the same dose level, they do not result in the same post-yield hardening behavior. For neutron irradiation, the true stress flow curves of the irradiated material can be made to superimpose on that of the unirradiated material, when the former are shifted appropriately along the strain axis. This behavior suggests that neutron irradiation hardening has the same effect as strain hardening for all of the materials analyzed. For electron irradiated steels, the

  4. Mechanisms of formation of hardening precipitates and hardening in aging of Al-Li-Cu-Mg model alloys with silver additions

    NASA Astrophysics Data System (ADS)

    Alekseev, A. A.; Zhuravleva, P. L.; Onuchina, M. R.; Klochkova, Yu. Yu.

    2015-11-01

    The mechanisms of the influence of silver additions on the phase transformations that occur in aging are revealed. The contribution of Ω'-phase particles to the deformation stress in Al alloys is estimated. The mechanisms of the effect of low (up to 0.5 wt %) silver additions and the copper content on the structure of the Ω'-phase precipitates in Al alloys are found. According to the proposed model, silver atoms remain immobile during the decomposition of a solid solution and nucleation centers of the Ω' phase form near them in low-temperature aging. Upon hardening aging, fragmented Ω'-phase particles intersect with each other, and the contribution of the intersection regions to the hardening of alloys by Ω'-phase particles is principal.

  5. Analysis of hardening behavior of sheet metals by a new simple shear test method taking into account the Bauschinger effect

    NASA Astrophysics Data System (ADS)

    Bang, Sungsik; Rickhey, Felix; Kim, Minsoo; Lee, Hyungyil; Kim, Naksoo

    2013-12-01

    In this study we establish a process to predict hardening behavior considering the Bauschinger effect for zircaloy-4 sheets. When a metal is compressed after tension in forming, the yield strength decreases. For this reason, the Bauschinger effect should be considered in FE simulations of spring-back. We suggested a suitable specimen size and a method for determining the optimum tightening torque for simple shear tests. Shear stress-strain curves are obtained for five materials. We developed a method to convert the shear load-displacement curve to the effective stress-strain curve with FEA. We simulated the simple shear forward/reverse test using the combined isotropic/kinematic hardening model. We also investigated the change of the load-displacement curve by varying the hardening coefficients. We determined the hardening coefficients so that they follow the hardening behavior of zircaloy-4 in experiments.

  6. Microstructure evolution in age-hardenable aluminium alloy during processing by hydrostatic extrusion.

    PubMed

    Lewandowska, M

    2006-10-01

    In the present work, scanning and transmission electron microscopy were used to investigate the microstructural evolution occurring during the hydrostatic extrusion of an age-hardenable aluminium alloy. It was shown that processing by hydrostatic extrusion leads to grain refinement to 95 nm in equivalent diameter. Hydrostatic extrusion also influences the geometrical parameters of two different types of particle: intermetallic inclusions and precipitates. The intermetallic inclusions slightly decrease in mean equivalent diameter, but their size remains at the micrometre level. The precipitates are fragmented to nanoscale spherical particles, and their evolution delays the process of grain refinement. PMID:17100901

  7. Transmission and scanning electron microscope study on the secondary cyclic hardening behavior of interstitial-free steel

    SciTech Connect

    Shih, Chia-Chang; Ho, New-Jin; Huang, Hsing-Lu

    2009-11-15

    Strain controlled fatigue experiment was employed to evaluate automotive grade interstitial-free ferrite steel. Hundreds of grains were examined by scanning electron microscope under electron channeling contrast image technique of backscattered electron image mode for comprehensive comparison of micrographs with those taken under transmission electron microscope. The cyclic stress responses clearly revealed that rapid hardening occurs at the early stage of cycling as a result of multiplication of dislocations to develop loop patches, dipolar walls and dislocation cells at various total strain amplitudes. After primary rapid hardening, stress responses varied from being saturated to further hardening according to dislocation structure evolution at various strain amplitudes. The fatigue failure was always accompanied with further hardening including secondary hardening. The corresponding dislocation structures with the three types of hardening behaviors are discussed. Once the secondary hardening starts, dislocation cells began to develop along grain boundaries in the low strain region and then extended into grain interiors as strain amplitudes increased and cycling went on. The secondary hardening rates were found to be directly proportional to their strain amplitudes.

  8. 3D dislocation dynamics: stress-strain behavior and hardening mechanisms in FCC and BCC metals

    SciTech Connect

    Hirth, J P; Rhee, M; Zhib, H M; de la Rubia, T D

    1999-02-19

    A dislocation dynamics (DD) model for plastic deformation, connecting the macroscopic mechanical properties to basic physical laws governing dislocation mobility and related interaction mechanisms, has been under development. In this model there is a set of critical reactions that determine the overall results of the simulations, such as the stress-strain curve. These reactions are, annihilation, formation of jogs, junctions, and dipoles, and cross-slip. In this paper we discuss these reactions and the manner in which they influence the simulated stress- strain behavior in fcc and bcc metals. In particular, we examine the formation (zipping) and strength of dipoles and junctions, and effect of jogs, using the dislocation dynamics model. We show that the strengths (unzipping) of these reactions for various configurations can be determined by direct evaluation of the elastic interactions. Next, we investigate the phenomenon of hardening in metals subjected to cascade damage dislocations. The microstructure investigated consists of small dislocation loops decorating the mobile dislocations. Preliminary results reveal that these loops act as hardening agents, trapping the dislocations and resulting in increased hardening.

  9. Investigation of Clusters in Medium Carbon Secondary Hardening Ultra-high-strength Steel After Hardening and Aging Treatments

    NASA Astrophysics Data System (ADS)

    Veerababu, R.; Balamuralikrishnan, R.; Muraleedharan, K.; Srinivas, M.

    2015-06-01

    Clusters, containing between 10 and 1000 atoms, have been investigated in a martensitic secondary hardening ultra-high-strength steel austenitized at 1173 K (900 °C) for 1 hour and tempered at either 768 K or 783 K (495 °C or 510 °C) for 4 or 8 hours using 3D atom probe. The presence of clusters was unambiguously established by comparing the observed spatial distribution of the different alloying elements against the corresponding distribution expected for a random solid solution. Maximum separation envelope method has been used for delineating the clusters from the surrounding "matrix." Statistical analysis was used extensively for size and composition analyses of the clusters. The clusters were found to constitute a significant fraction accounting for between 1.14 and 2.53 vol pct of the microstructure. On the average, the clusters in the 783 K (510 °C) tempered sample were coarser by ~65 pct, with an average diameter of 2.26 nm, relative to the other samples. In all samples, about 85 to 90 pct of the clusters have size less than 2 nm. The percentage frequency histograms for carbon content of the clusters in 768 K and 783 K (495 °C and 510 °C) tempered samples revealed that the distribution shifts toward higher carbon content when the tempering temperature is higher. It is likely that the presence of these clusters exerts considerable influence on the strength and fracture toughness of the steel.

  10. Correlation of Fe/Cr phase decomposition process and age-hardening in Fe-15Cr ferritic alloys

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Kimura, Akihiko; Han, Wentuo

    2014-12-01

    The effects of thermal aging on the microstructure and mechanical properties of Fe-15Cr ferritic model alloys were investigated by TEM examinations, micro-hardness measurements and tensile tests. The materials used in this work were Fe-15Cr, Fe-15Cr-C and Fe-15Cr-X alloys, where X refers to Si, Mn and Ni to simulate a pressure vessel steel. Specimens were isothermally aged at 475 °C up to 5000 h. Thermal aging causes a significant increase in the hardness and strength. An almost twice larger hardening is required for embrittlement of Fe-15Cr-X relative to Fe-15Cr. The age-hardening is mainly due to the formation of Cr-rich α‧ precipitates, while the addition of minor elements has a small effect on the saturation level of age-hardening. The correlation of phase decomposition process and age-hardening in Fe-15Cr alloy was interpreted by dispersion strengthened models.

  11. Investigation of hardening behavior in Xe ion-irradiated Zr-1Nb

    NASA Astrophysics Data System (ADS)

    Yan, Chunguang; Wang, Rongshan; Dai, Xianyuan; Wang, Yanli; Wang, Xitao; Bai, Guanghai; Zhang, Yanwei

    2016-05-01

    Irradiation hardening behavior of Zr-1Nb was examined by nanoindentation, slow positron annihilation technique, transmission electron microscopy and coplanar extremely asymmetric X-ray diffraction technique. Samples were irradiated at a dose rate of 2.78 × 10-4 dpa/s to peak doses of 0.15, 0.5, 1.5 and 2.5 dpa with 6.37 MeV Xe26+ ion beam at room temperature. The increase in hardness as a function of dose followed a power law expression with the exponent of 0.46. With increasing irradiation dose, more mono-, di- and trivacancies were induced, but their concentration remained constant once formed due to the equilibrium between the formation and recombination of vacancy type clusters during irradiation. Meanwhile, the dislocation loops were also introduced and their linear density increased with dose. The dislocation loops played an important role in the irradiation hardening behavior. But the exact contribution of each microstructural components to the overall hardness still needs further study.

  12. Fatigue Hardening Behavior of 1.5 GPa Grade Transformation-Induced Plasticity-Aided Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Sugimoto, Koh-Ichi; Hojo, Tomohiko

    2016-04-01

    Low cycle fatigue hardening/softening behavior of a 0.2 pct C-1.5 pct Si-1.5 pct Mn-1.0 pct Cr-0.2 pct Mo-0.05 pct Nb transformation-induced plasticity (TRIP)-aided steel consisting of a wide lath martensite structure matrix and a narrow lath martensite-metastable retained austenite mixture was investigated. The steel exhibited notable fatigue hardening in the same way as TRIP-aided bainitic ferrite steel, although conventional martensitic steel such as SCM420 steel with the same tensile strength exhibited fatigue softening. The considerable fatigue hardening of this steel is believed to be associated mainly with the compressive internal stress that results from a difference in flow stress between the matrix and the martensite-austenite-like phase, with a small contribution from the strain-induced transformation and dislocation hardenings.

  13. Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation

    NASA Technical Reports Server (NTRS)

    Miner, R. V.; Castelli, M. G.

    1992-01-01

    The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

  14. Friction stir welding of thin-sheet, age-hardenable aluminum alloys: A study of process/structure/property relationships

    NASA Astrophysics Data System (ADS)

    Shukla, Alpesh Khushalchand

    Friction Stir Welding (FSW) is a relatively new joining process that, as a solid-state process, offers several advantages over conventional fusion welding. Although FSW has been used extensively for the joining of age-hardenable aluminum alloys, the detailed effects of process parameters on the microstructures and mechanical properties of these welds have not been studied, especially for thin-sheet alloys. The present study investigated the FSW of thin-sheet, age-hardenable aluminum alloys, including: the development and optimization of welding process parameters that produce high-integrity, defect-free welds; the systematic evaluation of the effect of the base metal microstructure, FSW process parameters, and corresponding weld zone thermal conditions on microstructure evolution across the weld zone; the analysis of FSW mechanical properties and fracture behavior; and the development of relationships between the process parameters, microstructure, properties, and fracture that allow the optimization of weld performance. Two alloy systems, viz., Al-Cu-Mg (2024) and Al-Cu-Li (2195) in naturally-aged and artificially-aged conditions, respectively, were studied. Process optimization in 1 mm thick 2024-T3 sheet resulted in superior properties versus those of FS welds in thick sheet and plate, and nearly 100% joint efficiency. Microstructures, hardness and tensile properties of FS welds in 2024-T3 exhibited a strong dependency on process parameters. The heat of welding promoted various weld zone microstructures that were produced via the dissolution of base metal GPB zones, the nucleation of GBP and GPB II, and the nucleation and coarsening of S phase. SZ hardness for 2024-T3 welds exhibited a strong, but unusual dependency on the FSW process parameters, which was related to different mechanisms related to GPB zone formation. The microstructures of FS welds in 1 mm thick 2195-T8 were generally insensitive to the FSW process parameters. For all weld heat inputs, FSW

  15. Thermomechanical cyclic hardening behavior of Hastelloy-X. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Bartolotta, P. A.

    1985-01-01

    Experimental evidence of thermomechanical history dependence on the cyclic hardening behavior of a representative combustor liner material Hastelloy-X is presented, along with a discussion about the relevant concept of thermomechanical path dependence. Based on the experimental results, a discussion is given on the inadequacy of formulating nonisothermal constitutive equations solely on the basis of isothermal testing. Finally, the essence of a mathematical representation of thermoviscoplasticity is presented that qualitatively accounts for the observed hereditary behavior. This is achieved by formulating the scaler evolutionary equation in an established viscoplastic theory to reflect thermomechanical path dependence. Although the necessary nonisothermal tests for further quantifying the thermoviscoplastic model have been identified, such data are not yet available.

  16. Explosion in the Granite Field: Hardening and Softening Behavior in Rocks

    SciTech Connect

    Lomov, I N; Antoun, T H; Glenn, L A

    2001-06-25

    Properties of rock materials under quasistatic conditions are well characterized in laboratory experiments. Unfortunately, quasistatic data alone are not sufficient to calibrate models for use to describe inelastic wave propagation associated with conventional and nuclear explosions, or with impact. First, rock properties are size-dependent. properties measured using laboratory samples on the order of a few centimeters in size need to be modified to adequately describe wave propagation in a problem on the order of a few hundred meters in size. Second, there is lack of data about the damage (softening) behavior of rock because most laboratory tests focus on the pre-peak hardening region with very little emphasis on the post-peak softening region. This paper presents a model for granite that accounts for both the hardening and softening of geologic materials, and also provides a simple description of rubblized rock. The model is shown to reproduce results of quasistatic triaxial experiments as well as peak velocity and peak displacement attenuation from a compendium of dynamic wave propagation experiments that includes US and French nuclear tests in granite.

  17. Explosion in the Granite Field: Hardening and Softening Behavior in Rocks

    SciTech Connect

    Lomov, I N; Antoun, T H; Glenn, L A

    2001-07-12

    Properties of rock materials under quasistatic conditions are well characterized in laboratory experiments. Unfortunately, quasistatic data alone are not sufficient to calibrate models for use to describe inelastic wave propagation associated with conventional and nuclear explosions, or with impact. First, rock properties are size-dependent. properties measured using laboratory samples on the order of a few centimeters in size need to be modified to adequately describe wave propagation in a problem on the order of a few hundred meters in size. Second, there is lack of data about the damage (softening) behavior of rock because most laboratory tests focus on the pre-peak hardening region with very little emphasis on the post-peak softening region. This paper presents a model for granite that accounts for both the hardening and softening of geologic materials, and also provides a simple description of rubblized rock. The model is shown to reproduce results of quasistatic triaxial experiments as well as peak velocity and peak displacement attenuation from a compendium of dynamic wave propagation experiments that includes US and French nuclear tests in granite.

  18. Effect of Hf on structure and age hardening of Ti–Al-N thin films

    PubMed Central

    Rachbauer, R.; Blutmager, A.; Holec, D.; Mayrhofer, P.H.

    2012-01-01

    Protective coatings for high temperature applications, as present e.g. during cutting and milling operations, require excellent mechanical and thermal properties during work load. The Ti1 − xAlxN system is industrially well acknowledged as it covers some of these requirements, and even exhibits increasing hardness with increasing temperature in its cubic modification, known as age hardening. The thermally activated diffusion at high temperatures however enables for the formation of wurtzite AlN, which causes a rapid reduction of mechanical properties in Ti1 − xAlxN coatings. The present work investigates the possibility to increase the formation temperature of w-AlN due to Hf alloying up to 10 at.% at the metal sublattice of Ti1 − xAlxN films. Ab initio predictions on the phase stability and decomposition products of quaternary Ti1 − x − yAlxHfyN alloys, as well as the ternary Ti1 − xAlxN, Hf1 − xAlxN and Ti1 − zHfzN systems, facilitate the interpretation of the experimental findings. Vacuum annealing treatments from 600 to 1100 °C indicate that the isostructural decomposition, which is responsible for age hardening, of the Ti1 − x − yAlxHfyN films starts at lower temperatures than the ternary Ti1 − xAlxN coating. However, the formation of a dual phase structure of c-Ti1 − zHfzN (with z = y/(1 − x)) and w-AlN is shifted to ~ 200 °C higher temperatures, thus retaining a film hardness of ~ 40 GPa up to ~ 1100 °C, while the Hf free films reach the respective hardness maximum of ~ 38 GPa already at ~ 900 °C. Additional annealing experiments at 850 and 950 °C for 20 h indicate a substantial improvement of the oxidation resistance with increasing amount of Hf in Ti1 − x − yAlxHfyN. PMID:22319223

  19. Evaluation of hardening behaviors in ion-irradiated Fe-9Cr and Fe-20Cr alloys by nanoindentation technique

    NASA Astrophysics Data System (ADS)

    Li, Shilei; Wang, Yanli; Dai, Xianyuan; Liu, Fang; Li, Jinyu; Wang, Xitao

    2016-09-01

    The ion irradiation hardening behaviors of Fe-9 wt% Cr and Fe-20 wt% Cr model alloys were investigated by nanoindentation technique. The specimens were irradiated with 3 MeV Fe11+ ions at room temperature up to 1 and 5 dpa for Fe-9Cr alloy and 1 and 2.5 for Fe-20Cr alloy. The ratio of average hardness in the same depth of irradiated and unirradiated (Hirr. av/Hunirr. av) was used to determine the critical indentation depth hcrit to eliminate the softer substrate effect. The Nix-Gao model was used to explain the indentation size effect. Irradiation hardening is clearly observed in both Fe-9Cr alloy and Fe-20Cr alloy after ion irradiation. The differences of ISE and irradiation hardening behaviors between Fe-9Cr and Fe-20Cr alloys are considered to be due to their different microstructures and microstructural evolution under ion irradiation.

  20. Large Scale 3-D Dislocation Dynamics and Atomistic Simulations of Flow and Strain-Hardening Behavior of Metallic Micropillars

    NASA Astrophysics Data System (ADS)

    Rao, Satish

    2015-03-01

    Experimental studies show strong strengthening effects for micrometer-scale FCC as well as two-phase superalloy crystals, even at high initial dislocation densities. This talk shows results from large-scale 3-D discrete dislocation simulations (DDS) used to explicitly model the deformation behavior of FCC Ni (flow stress and strain-hardening) as well as superalloy microcrystals for diameters ranging from 1 - 20 microns. The work shows that two size-sensitive athermal hardening processes, beyond forest and precipitation hardening, are sufficient to develop the dimensional scaling of the flow stress, stochastic stress variation, flow intermittency and, high initial strain-hardening rates, similar to experimental observations for various materials. In addition, 3D dislocation dynamics simulations are used to investigate strain-hardening characteristics and dislocation microstructure evolution with strain in large 20 micron size Ni microcrystals (bulk-like) under three different loading axes: 111, 001 and 110. Three different multi-slip loading axes, < 111 > , < 001 > and < 110 > , are explored for shear strains of ~0.03 and final dislocation densities of ~1013/m2. The orientation dependence of initial strain hardening rates and dislocation microstructure evolution with strain are discussed. The simulated strain hardening results are compared with experimental data under similar loading conditions from bulk single-crystal Ni. Finally, atomistic simulation results on the operation of single arm sources in Ni bipillars with a large angle grain boundary is discussed. The atomistic simulation results are compared with experimental mechanical behavior data on Cu bipillars with a similar large angle grain boundary. This work was supported by AFOSR (Dr. David Stargel), and by a grant of computer time from the DOD High Performance Computing Modernization Program, at the Aeronautical Systems Center/Major Shared Resource Center.

  1. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-12-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  2. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-09-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  3. Influence of cold rolling degree and ageing treatments on the precipitation hardening of 2024 and 7075 alloys

    NASA Astrophysics Data System (ADS)

    Naimi, A.; Yousfi, H.; Trari, M.

    2013-08-01

    In the present work, the precipitation hardening of 2024 and 7075 aluminum alloys is investigated as a function of cold rolling degree, ageing time and temperature using Vickers microhardness measurements and differential scanning calorimetry (DSC). It is found that a variation in such parameters can improve the hardness and plays an important role in the precipitation hardening process. At specific ageing temperature, the large cold rolled 7075 alloy exhibits two peaks of hardness. Moreover, for both alloys, the increment of hardness during ageing decreases with increasing the cold rolling degree. While in some cases microhardness measurements give impression that the precipitation reaction is slowed down by deformation, DSC analysis indicates that the precipitation is much accelerated since only a slight deformation decreases strongly the temperatures of reactions. However, the degree of cold rolling does not play a crucial role.

  4. Influence of Secondary Cyclic Hardening on the Low Cycle Fatigue Behavior of Nitrogen Alloyed 316LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Prasad Reddy, G. V.; Sandhya, R.; Mathew, M. D.; Sankaran, S.

    2013-12-01

    In this article, the occurrence of secondary cyclic hardening (SCH) and its effect on high-temperature cyclic deformation and fatigue life of 316LN Stainless steel are presented. SCH is found to result from planar slip mode of deformation and enhance the degree of hardening over and above that resulted from dynamic strain aging. The occurrence of SCH is strongly governed by the applied strain amplitude, test temperature, and the nitrogen content in the 316LN SS. Under certain test conditions, SCH is noticed to decrease the low cycle fatigue life with the increasing nitrogen content.

  5. Measurement and material modeling of biaxial work-hardening behavior for pure titanium sheet

    NASA Astrophysics Data System (ADS)

    Sumita, Takeshi; Kuwabara, Toshihiko

    2013-12-01

    Biaxial tensile tests of a commercial pure titanium sheet (JIS ♯1) were performed using a servo-controlled multiaxial tube expansion testing machine developed by one of the authors [Kuwabara, T. and Sugawara, F., Multiaxial tube expansion test method for measurement of sheet metal deformation behavior under biaxial tension for a large strain range, Int. J. Plasticity, 45 (2013), 103-118]. Tubular specimens with an inner diameter of 54 mm were fabricated by roller bending and TIG welding the as-received test material with a thickness of 0.5 mm. Several linear stress paths in the first quadrant of the stress space were applied to the tubular specimens to measure the contours of plastic work and the directions of the plastic strain rates for an equivalent plastic strain range of 0.05 ≤ ɛ0p ≤ 0.30. It was found that the shapes of the work contours significantly changed with an increase in ɛ0p and that the Yld2000-2d yield function could reproduce the differential work hardening behavior of the test material by changing the material parameters and the exponent as functions of ɛ0p.

  6. Effect of prior oxidation on the creep behavior of NiAl-hardened austenitic steel

    NASA Astrophysics Data System (ADS)

    Satyanarayana, D. V. V.; Malakondaiah, G.; Sarma, D. S.

    2003-11-01

    The effect of prior oxidation at 1473 K on the creep behavior of an Fe-Ni-Cr-Al alloy, hardened by ordered NiAl precipitates, has been investigated at 873 K over a stress range of 275 to 450 MPa. The alloy in the as-electroslag remelted (ESR) as well as the ESR-plus-hot-worked conditions was considered. Prior oxidation causes creep strengthening in the Fe-Ni-Cr-Al alloy, resulting in a decrease in minimum creep rate and increase in time to rupture, in contrast to the observations reported on nickel-based superalloys. Creep strengthening is, however, accompanied by a significant reduction in creep ductility. Oxidation-induced creep strengthening in the current alloy can be attributed to the improved adherence of surface oxide caused by the presence of yttrium. An effective stress that incorporates the contributions of load transfer as well as substructural strengthening is used to account for the observed oxidation-induced creep strengthening. While creep strengthening is more pronounced in the ESR cast alloy, the loss in creep ductility is more intense in the ESR wrought alloy. Increasing the oxidation time beyond 1 hour has a minimal effect on creep strengthening of both the alloys, though it lowers significantly the creep ductility of the wrought alloy. The observed differences in creep behavior of the alloy in the two different conditions could be attributed to the differences in grain size as well as morphology and related oxidation-induced damage.

  7. The effect of twinning on the work hardening behavior in Hafnium

    SciTech Connect

    Cerreta, E. K.; Gray, G. T. , III; Yablinsky, C.

    2004-01-01

    In many HCP metals, both twinning and slip are known to be important modes of deformation. However, the interaction of the two mechanisms and their effect on work hardening is not well understood. In hafnium, twinning and work hardening rates increase with increasing strain, increasing strain rate, and decreasing temperature. At low strains and strain rates and at higher temperatures, slip dominates deformation and rates of work hardening are relatively lower. To characterize the interaction of slip and twinning, Hf specimens were prestrained quasi-statically in compression at 77K, creating specimens that were heavily twinned. These specimens were subsequently reloaded at room temperature. Twinning within the microstructures was characterized optically and using transmission electron microscopy. The interaction of slip with the twins was investigated as a function of prestrain and correlated with the observed rates of work hardening.

  8. Aging behavior and mechanical properties of maraging steels in the presence of submicrocrystalline Laves phase particles

    SciTech Connect

    Mahmoudi, A.; Ghavidel, M.R. Zamanzad; Nedjad, S. Hossein; Heidarzadeh, A.; Ahmadabadi, M. Nili

    2011-10-15

    Cold rolling and annealing of homogenized Fe-Ni-Mn-Mo-Ti-Cr maraging steels resulted in the formation of submicrocrystalline Fe{sub 2}(Mo,Ti) Laves phase particles. Optical and scanning electron microscopy, X-ray diffraction, tensile and hardness tests were used to study the microstructure, aging behavior and mechanical properties of the annealed steels. The annealed microstructures showed age hardenability during subsequent isothermal aging at 753 K. Ultrahigh fracture stress but poor tensile ductility was obtained after substantial age hardening in the specimens with 2% and 4% chromium. Increasing chromium addition up to 6% toughened the aged microstructure at the expense of the fracture stress by increasing the volume fraction of retained austenite. The Laves phase particles acted as crack nucleation sites during tensile deformation. - Highlights: {yields} Laves phases dispersed in a BCC iron matrix by annealing of cold rolled samples. {yields} The samples showed age hardenability during subsequent isothermal aging at 753 K. {yields} Ultrahigh fracture stress but poor ductility was obtained after age hardening. {yields} Increasing chromium addition toughened the aged microstructure. {yields} Laves phase particles acting as crack nucleation sites during tensile deformation.

  9. [Study on the age-hardenable silver alloy (3 rd report). III. On the ageing process of dental Ag-Pd-Cu-Au alloy (author's transl)].

    PubMed

    Ota, M; Hisatsune, K; Yamane, M

    1975-05-01

    The precipitation hardening process of a dental silver base alloy, Ag-28 Pd-10 Cu-12 wt % Au, was studied by means of X-ray diffraction, hardness measurement and metallographic observations. After solution treatment at 900 degrees C for 30 min, specimens were subjected to anisothermal annealing at the rate of 1 degrees C/min. PdCu ordered phase and alpha2 solid solution (Ag rich phase) precipitated hetelogeneously at the grain boundaries and then grew up into each grain. Drastic increase in hardness was recognized with the spread of nodular region. Electron microscopic observation of these precipitates showed very fine lamellar structure. It is concluded that the age hardening of this alloy could be attributed to this grain boundary precipitation and the softening at the overaged stage to the second grain boundary reaction which produced very coarse lamellar structure. PMID:1058263

  10. Significant contribution of stacking faults to the strain hardening behavior of Cu-15%Al alloy with different grain sizes

    NASA Astrophysics Data System (ADS)

    Tian, Y. Z.; Zhao, L. J.; Chen, S.; Shibata, A.; Zhang, Z. F.; Tsuji, N.

    2015-11-01

    It is commonly accepted that twinning can induce an increase of strain-hardening rate during the tensile process of face-centered cubic (FCC) metals and alloys with low stacking fault energy (SFE). In this study, we explored the grain size effect on the strain-hardening behavior of a Cu-15 at.%Al alloy with low SFE. Instead of twinning, we detected a significant contribution of stacking faults (SFs) irrespective of the grain size even in the initial stage of tensile process. In contrast, twinning was more sensitive to the grain size, and the onset of deformation twins might be postponed to a higher strain with increasing the grain size. In the Cu-15 at.%Al alloy with a mean grain size of 47 μm, there was a stage where the strain-hardening rate increases with strain, and this was mainly induced by the SFs instead of twinning. Thus in parallel with the TWIP effect, we proposed that SFs also contribute significantly to the plasticity of FCC alloys with low SFE.

  11. Significant contribution of stacking faults to the strain hardening behavior of Cu-15%Al alloy with different grain sizes

    PubMed Central

    Tian, Y. Z.; Zhao, L. J.; Chen, S.; Shibata, A.; Zhang, Z. F.; Tsuji, N.

    2015-01-01

    It is commonly accepted that twinning can induce an increase of strain-hardening rate during the tensile process of face-centered cubic (FCC) metals and alloys with low stacking fault energy (SFE). In this study, we explored the grain size effect on the strain-hardening behavior of a Cu-15 at.%Al alloy with low SFE. Instead of twinning, we detected a significant contribution of stacking faults (SFs) irrespective of the grain size even in the initial stage of tensile process. In contrast, twinning was more sensitive to the grain size, and the onset of deformation twins might be postponed to a higher strain with increasing the grain size. In the Cu-15 at.%Al alloy with a mean grain size of 47 μm, there was a stage where the strain-hardening rate increases with strain, and this was mainly induced by the SFs instead of twinning. Thus in parallel with the TWIP effect, we proposed that SFs also contribute significantly to the plasticity of FCC alloys with low SFE. PMID:26582568

  12. Hardening of the arteries

    MedlinePlus

    Atherosclerosis; Arteriosclerosis; Plaque buildup - arteries; Hyperlipidemia - atherosclerosis; Cholesterol - atherosclerosis ... Hardening of the arteries often occurs with aging. As you grow older, ... narrows your arteries and makes them stiffer. These changes ...

  13. Unveiling the Origin of Work Hardening Behavior in an Ultrafine-Grained Manganese Transformation-Induced Plasticity Steel by Hydrogen Investigation

    NASA Astrophysics Data System (ADS)

    Zhu, Xu; Li, Wei; Zhao, Hongshan; Han, Qihang; Wang, Li; Jiao, Huisheng; Jin, Xuejun

    2016-09-01

    To reveal the origin of work hardening behavior in an ultrafine-grained manganese transformation-induced plasticity (TRIP) steel, specific experiments were designed with the assistance of hydrogen. Although the effect of hydrogen on the austenite transformation was negligible, the work hardening rate ( Θ) was apparently reduced for hydrogenated samples, indicating that TRIP effect cannot account for the high Θ alone. The collaborative effect of dislocation accumulation in ferrite and austenite transformation is proposed to explain the responsible mechanism.

  14. Unveiling the Origin of Work Hardening Behavior in an Ultrafine-Grained Manganese Transformation-Induced Plasticity Steel by Hydrogen Investigation

    NASA Astrophysics Data System (ADS)

    Zhu, Xu; Li, Wei; Zhao, Hongshan; Han, Qihang; Wang, Li; Jiao, Huisheng; Jin, Xuejun

    2016-07-01

    To reveal the origin of work hardening behavior in an ultrafine-grained manganese transformation-induced plasticity (TRIP) steel, specific experiments were designed with the assistance of hydrogen. Although the effect of hydrogen on the austenite transformation was negligible, the work hardening rate (Θ) was apparently reduced for hydrogenated samples, indicating that TRIP effect cannot account for the high Θ alone. The collaborative effect of dislocation accumulation in ferrite and austenite transformation is proposed to explain the responsible mechanism.

  15. The Strain-Hardening Behavior of Partially Austenitized and the Austempered Ductile Irons with Dual Matrix Structures

    NASA Astrophysics Data System (ADS)

    Kilicli, Volkan; Erdogan, Mehmet

    2008-04-01

    In the current study, an unalloyed ductile iron containing 3.50 C wt.%, 2.63 Si wt.%, 0.318 Mn wt.%, and 0.047 Mg wt.% was intercritically austenitized (partially austenitized) in two-phase regions (α + γ) at different temperatures for 20 min and then was quenched into salt bath held at austempering temperature of 365 °C for various times to obtain different ausferrite plus proeutectoid ferrite volume fractions. Fine and coarse dual matrix structures (DMS) were obtained from two different starting conditions. Some specimens were also conventionally austempered from 900 °C for comparison. The results showed that a structure having proeutectoid ferrite plus ausferrite (bainitic ferrite + high-carbon austenite (retained or stabilized austenite)) has been developed. Both of the specimens with ˜75% ausferrite volume fraction (coarse structure) and the specimen with ˜82% ausferrite volume fraction (fine structure) exhibited the best combination of high strength and ductility compared to the pearlitic grades, but their ductility is slightly lower than the ferritic grades. These materials also satisfy the requirements for the strength of the quenched and tempered grades and their ductility is superior to this grade. The correlation between the strain-hardening rates of the various austempered ductile iron (ADI) with DMS and conventionally heat-treated ADI microstructures as a function of strain was conducted by inspection of the respective tensile curves. For this purpose, the Crussard-Jaoul (C-J) analysis was employed. The test results also indicate that strain-hardening behavior of ADI with dual matrix is influenced by the variations in the volume fractions of the phases, and their morphologies, the degree of ausferrite connectivity and the interaction intensities between the carbon atoms and the dislocations in the matrix. The ADI with DMS generally exhibited low strain-hardening rates compared to the conventionally ADI.

  16. The effects of solution treatment on the mechanical properties of age-hardened A-286 bar stock at elevated and cryogenic temperature

    NASA Technical Reports Server (NTRS)

    Montano, J. W.

    1972-01-01

    The mechanical properties are presented of solution treated and age hardened A-286 corrosion resistant steel bar stock. Material solution treated at 899 C or 982 C, each followed by an age hardening treatment of 718 C, was evaluated. Test specimens manufactured from 1.50 inch (3.81 cm) diameter bar stock were tested at temperatures from +649 C to -253 C. The test data indicated excellent tensile, yield, elongation and reduction-in-area properties at all testing temperatures for both solution treated and aged materials. Cryogenic temperature notched tensile, impact, and shear tests indicated excellent notch strength, ductility, and shear values. There was very little difference in the mechanical properties of the two solution treated and aged materials. The only exception was that the 962 C solution treated and aged material had superior stress rupture properties at 649 C.

  17. Age Related Changes in Preventive Health Behavior.

    ERIC Educational Resources Information Center

    Leventhal, Elaine A.; And Others

    Health behavior may be influenced by age, beliefs, and symptomatology. To examine age-related health beliefs and behaviors with respect to six diseases (the common cold, colon-rectal cancer, lung cancer, heart attack, high blood pressure, and senility), 396 adults (196 males, 200 females) divided into three age groups completed a questionnaire…

  18. Impact properties and hardening behavior of laser and electron-beam welds of V-4Cr-4Ti

    SciTech Connect

    Chung, H.M.; Strain, R.V.; Tsai, H.C.; Park, J.H.; Smith, D.L.

    1996-10-01

    The authors are conducting a program to develop an optimal laser welding procedure that can be applied to large-scale fusion-reactor structural components to be fabricated from vanadium-base alloys. Results of initial investigation of mechanical properties and hardening behavior of laser and electron-beam (EB) welds of the production-scale heat of V-4Cr-4Ti (500-kg Heat 832665) in as-welded and postwelding heat-treated (PWHT) conditions are presented in this paper. The laser weld was produced in air using a 6-kW continuous CO{sub 2} laser at a welding speed of {approx}45 mm/s. Microhardness of the laser welds was somewhat higher than that of the base metal, which was annealed at a nominal temperature of {approx}1050{degrees}C for 2 h in the factory. In spite of the moderate hardening, ductile-brittle transition temperatures (DBTTs) of the initial laser ({approx}80{degrees}C) and EB ({approx}30{degrees}C) welds were significantly higher than that of the base metal ({approx}{minus}170{degrees}C). However, excellent impact properties, with DBTT < {minus}80{degrees}C and similar to those of the base metal, could be restored in both the laser and EB welds by postwelding annealing at 1000{degrees}C for 1 h in vacuum.

  19. Healthy Behaviors or Age Denials?

    ERIC Educational Resources Information Center

    Palmore, Erdman B.

    2007-01-01

    There is considerable confusion in the media and the public about healthy behaviors in contrast to "antiaging" behaviors designed to make one look "younger." As an aid in clarifying the differences between these two types of behaviors, we have developed a questionnaire called the Health Behavior Inventory (HBI). We also wanted to estimate…

  20. Pulse wave velocity and age- and gender-dependent aortic wall hardening in fowl

    PubMed Central

    Ruiz-Feria, Ciro A.; Yang, Yimu; Thomason, Donald B.; White, Jarred; Su, Guibin; Nishimura, Hiroko

    2009-01-01

    Before sexual maturation, chickens (Gallus gallus) show high blood pressure (BP) and neointimal plaques in the lower abdominal aortae (AbA). We investigated age/sex-related changes in pulse wave velocity (PWV), elastin, collagen, and protein levels in AbA, and cardiac morphology to determine whether PWV increases during incremental increases in BP of maturing fowl, while arterial stiffness becomes dominant with aging. PWV (m/s) was significantly greater in male chicks (6-7 wk, 9.3 ± 0.8; females, 6.1 ± 0.5) and remained high in cockerels (13 wk), young (27-28 wk), and adults (44-66 wk). PWV increased in prepubertal pullets (10.0 ± 0.9), dropped significantly in young hens, and remained low in adults. In contrast, medial thickness, protein levels, and collagen levels increased, while elastin/collagen ratios decreased, with maturation/aging. Males had heavier ventricular mass and thicker ventricular walls than females at all ages; left ventricular thickness decreased with maturation/aging. Thus, sustained high BP may have caused progressive medial hypertrophy, increased aortic rigidity, and enlarged hearts with left ventricular dilation. PWV of AbA was already greater in male chicks at an age when both sexes have similar collagen levels and low protein levels, suggesting that a factor other than structural stiffness may be an important determinant of PWV. PMID:19689927

  1. Measurement of Work Hardening Behavior of Pure Titanium Sheet Using A Servo-Controlled Tube Bulge Testing Apparatus

    SciTech Connect

    Sumita, Takeshi; Kuwabara, Toshihiko; Hayashida, Yasuhiro

    2011-05-04

    Biaxial stress tests of rolled pure titanium sheet (JIS 1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure titanium sheet was bent and welded to make tubular specimens. Combined tension-internal pressure was applied to the tubular specimens using the servo-controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101-117 (2002)], so that the strain rate ratio, {epsilon}{sub {phi}}:{epsilon}{theta}, in the axial ({phi}) and circumferential ({theta}) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.

  2. Measurement of Work Hardening Behavior of Pure Titanium Sheet Using A Servo-Controlled Tube Bulge Testing Apparatus

    NASA Astrophysics Data System (ADS)

    Sumita, Takeshi; Kuwabara, Toshihiko; Hayashida, Yasuhiro

    2011-05-01

    Biaxial stress tests of rolled pure titanium sheet (JIS ♯1, 0.5 mm thick) have been carried out in order to investigate the anisotropic plastic deformation under biaxial tension. Rolled pure titanium sheet was bent and welded to make tubular specimens. Combined tension-internal pressure was applied to the tubular specimens using the servo-controlled tube bulge testing apparatus developed by one of the authors [Kuwabara, T., Yoshida, K., Narihara, K., Takahashi S., Int. J. Plasticity 21 (1), 101-117 (2002)], so that the strain rate ratio, ɛ˙φ:ɛ˙θ, in the axial (φ) and circumferential (θ) directions of the specimen was controlled to be constant. Contours of plastic work at different levels of plastic strain and stress paths under constant strain rate ratios have been observed in the first quadrant of stress space. It is found that the test material exhibits significant differential work hardening behavior with the increase of plastic work.

  3. The Effect of Physical Aging on the Deformation Behavior of Gelatin Films

    NASA Astrophysics Data System (ADS)

    Dai, Chi-An; Tsou, Andy H.

    1998-03-01

    Deformation behavior of gelatin as a function of its relaxation enthalpy (resulted from physical aging), its gel structure, and its hardener level is evaluated based on the uniaxial tensile testing of gelatin films. Optical microscopy examination of the fracture samples from the tensile testing at 20C and 50%RH (relative humidity) revealed that both brittle frature of crazing or cracking and shear yielding of shear cracking or shear banding are present in gelatin films. We have found that these deformation mechanisms are strongly dependent on the extent of physical aging and gel structure, but are not dependent on the hardener level. For low gel structure, gelatin deforms exclusively by crazing. For medium gel structure, there is a critical aging enthalpy above which gelatin deforms by craing and below which gelatin deforms by shear. For high gel structure, gelatin deforms exclusively by shear mechanism.

  4. Friction Stir Welding of Age-Hardenable Aluminum Alloys: A Parametric Approach Using RSM Based GRA Coupled With PCA

    NASA Astrophysics Data System (ADS)

    Vijayan, D.; Rao, V. S.

    2014-04-01

    Age-hardenable aluminum alloys, primarily used in the aerospace, automobile and marine industries (2×××, 6××× and 7×××), can be welded using solid-state welding techniques. Friction stir welding is an emerging solid-state welding technique used to join both similar and dissimilar materials. The strength of a friction stir welded joint depends on the joining process parameters. Therefore, a combination of the statistical techniques of a response surface methodology based on a grey relational analysis coupled to a principal component analysis was proposed to select the process parameters suitable for joining AA 2024 and AA 6061 aluminum alloys via friction stir welding. The significant process parameters, such as rotational speed, welding speed, axial load and pin shapes (PS) were considered during the statistical experiment. The results indicate that the square PS plays a vital role and yields an ultimate tensile strength of 141 MPa for an elongation of 12 % versus cylinder and taper pin profiles. The root cause for joint strength loss and fracture mode was analyzed using scanning electron microscopy. Severe material flow during macro defects, such as pin holes and porosity, degrades the joint strength by approximately 44 % for AA 2024 and 51 % for AA 6061 fabricated FS-welded aluminum alloys relative to the base material. The results of this approach are useful for accurately controlling the response and optimize the process parameters.

  5. Initial precipitation and hardening mechanism during non-isothermal aging in an Al–Mg–Si–Cu 6005A alloy

    SciTech Connect

    Yang, Wenchao; Ji, Shouxun; Huang, Lanping; Sheng, Xiaofei; Li, Zhou; Wang, Mingpu

    2014-08-15

    The characterization of precipitation and hardening mechanism during non-isothermal aging had been investigated using high resolution transmission electron microscopy for an Al–Mg–Si–Cu 6005A alloy. It was proposed that the needle-shaped β″ precipitates with a three-dimension coherency strain-field and an increased number density in the Al matrix provided the maximum strengthening effect for the Al–Mg–Si–Cu 6005A alloy. Simultaneously, it was also found that the formation and evolution of clusters in the early precipitation were associated with the vacancy binding energy, during which Si atoms played an important role in controlling the numbers density of Mg/Si co-clusters, and the excess Si atoms provided the increased number of nucleation sites for the subsequent precipitates to strengthen and improve the precipitation rate. Finally, based on the experimental observation and theoretical analysis, the precipitation sequence during the early precipitation in the Al–Mg–Si–Cu 6005A alloy was proposed as: supersaturated solid solution → Si-vacancy pairs, Mg-vacancy pairs and Mg clusters → Si clusters, and dissolution of Mg clusters → Mg atoms diffusion into the existing Si clusters → Mg/Si co-clusters → GP zone. - Highlights: • β″ precipitates provide the maximum strengthening effect for the 6005A alloy. • Si atoms play an important role in controlling the numbers of Mg/Si co-clusters. • The early aging sequence is deduced based on the solute-vacancy binding energy.

  6. Effect of numerical parameters on characterizing the hardening behavior of ductile uniaxial tension specimens.

    SciTech Connect

    Cordova, Theresa Elena; Dion, Kristin; Laing, John Robert; Corona, Edmundo; Breivik, Nicole L.; Wellman, Gerald William; Shelton, Timothy R.

    2010-11-01

    Many problems of practical importance involve ductile materials that undergo very large strains, in many cases to the point of failure. Examples include structures subjected to impact or blast loads, energy absorbing devices subjected to significant crushing, cold-forming manufacturing processes and others. One of the most fundamental pieces of data that is required in the analysis of this kind of problems is the fit of the uniaxial stress-strain curve of the material. A series of experiments where mild steel plates were punctured with a conical indenter provided a motivation to characterize the true stress-strain curve until the point of failure of this material, which displayed significant ductility. The hardening curve was obtained using a finite element model of the tensile specimens that included a geometric imperfection in the form of a small reduction in the specimen width to initiate necking. An automated procedure iteratively adjusted the true stress-strain curve fit used as input until the predicted engineering stress-strain curve matched experimental measurements. Whereas the fitting is relatively trivial prior to reaching the ultimate engineering stress, the fit of the softening part of the engineering stress-stain curve is highly dependent on the finite element parameters such as element formulation and initial geometry. Results by two hexahedral elements are compared. The first is a standard, under-integrated, uniform-strain element with hourglass control. The second is a modified selectively-reduced-integration element. In addition, the effects of element size, aspect ratio and hourglass control characteristics are investigated. The effect of adaptively refining the mesh based on the aspect ratio of the deformed elements is also considered. The results of the study indicate that for the plate puncture problem, characterizing the material with the same element formulation and size as used in the plate models is beneficial. On the other hand, using

  7. Evaluation of Solute Clusters Associated with Bake-Hardening Response in Isothermal Aged Al-Mg-Si Alloys Using a Three-Dimensional Atom Probe

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Kozuka, Masaya; Takaki, Yasuo; Sato, Tatsuo

    2014-12-01

    Temporal changes in the number density, size distribution, and chemical composition of clusters formed during natural aging at room temperature and pre-aging at 363 K (90 °C) in an Al-0.62Mg-0.93Si (mass pct) alloy were evaluated using atom probe tomography. More than 10 million atoms were examined in the cluster analysis, in which about 1000 clusters were obtained for each material after various aging treatments. The statistically proven records show that both number density and the average radius of clusters in pre-aged materials are larger than in naturally aged materials. It was revealed that the fraction of clusters with a low Mg/Si ratio after natural aging for a short time is higher than with other aging treatments, regardless of cluster size. This indicates that Si-rich clusters form more easily after short-period natural aging, and that Mg atoms can diffuse into the clusters or possibly form another type of Mg-Si cluster after prolonged natural aging. The formation of large clusters with a uniform Mg/Si ratio is encouraged by pre-aging. It can be concluded that an increase of small clusters with various Mg/Si ratios does not promote the bake-hardening (BH) response, whereas large clusters with a uniform Mg/Si ratio play an important role in hardening during the BH treatment at 443 K (170 °C).

  8. Evaluation of Solute Clusters Associated with Bake-Hardening Response in Isothermal Aged Al-Mg-Si Alloys Using a Three-Dimensional Atom Probe

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Kozuka, Masaya; Takaki, Yasuo; Sato, Tatsuo

    2014-09-01

    Temporal changes in the number density, size distribution, and chemical composition of clusters formed during natural aging at room temperature and pre-aging at 363 K (90 °C) in an Al-0.62Mg-0.93Si (mass pct) alloy were evaluated using atom probe tomography. More than 10 million atoms were examined in the cluster analysis, in which about 1000 clusters were obtained for each material after various aging treatments. The statistically proven records show that both number density and the average radius of clusters in pre-aged materials are larger than in naturally aged materials. It was revealed that the fraction of clusters with a low Mg/Si ratio after natural aging for a short time is higher than with other aging treatments, regardless of cluster size. This indicates that Si-rich clusters form more easily after short-period natural aging, and that Mg atoms can diffuse into the clusters or possibly form another type of Mg-Si cluster after prolonged natural aging. The formation of large clusters with a uniform Mg/Si ratio is encouraged by pre-aging. It can be concluded that an increase of small clusters with various Mg/Si ratios does not promote the bake-hardening (BH) response, whereas large clusters with a uniform Mg/Si ratio play an important role in hardening during the BH treatment at 443 K (170 °C).

  9. Aging Behavior of Al 6061 Alloy Processed by High-Pressure Torsion and Subsequent Aging

    NASA Astrophysics Data System (ADS)

    Mohamed, Intan Fadhlina; Lee, Seungwon; Edalati, Kaveh; Horita, Zenji; Hirosawa, Shoichi; Matsuda, Kenji; Terada, Daisuke

    2015-06-01

    A process to achieve strengthening in an Al 6061 alloy by grain refinement to ~200 nm using high-pressure torsion (HPT) and fine precipitation using aging treatment is studied. It is shown that although aging of the HPT-processed sample is effective for extra strengthening of the alloy, the imposed shear strain and the aging temperature should be selected carefully. The HPT processing after 5 turns leads high saturation hardness and tensile strength of 163 Hv and 470 MPa, respectively. The hardness at the saturation level remains the same during aging at 373 K (100 °C), while the hardness decreases by aging at 423 K (150 °C). When the disks are processed for 0.75 turns (lower shear strains) and aged at 373 K (100 °C), the hardness increases above the hardness level at the saturation because of the formation of B' and β' precipitates. Quantitative analyses indicate that three major hardening mechanisms contribute to the total hardening: grain boundary hardening through the Hall-Petch relationship, dislocation hardening through the Bailey-Hirsch relationship and precipitation hardening through the Orowan relationship. This study shows that the contribution of different strengthening mechanisms can be estimated using a linear additive relationship in ultrafine-grained aluminum alloys.

  10. Multi-stage Modeling of Lüders Elongation and Work-Hardening Behaviors of Ferrite Steels Under Tension

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongyang; Liao, Yiliang

    2016-04-01

    For structural and engineering steels, accurate modeling of stress-strain relation of ferrite phase is of particular importance, since the modeling results could benefit new material system design and process-microstructure-property analysis. Several modeling efforts have been made to achieve this target. However, few efforts have been put on the Lüders elongation behavior of ferrite. As a result, the modeling results from proposed models do not match well with experimental data, particularly at a relatively low-strain range. Furthermore, without the consideration of yield point elongation due to the formation of Lüders bands, additional calibration parameters are required to capture the stress level of stress-strain curves. In this work, a multi-stage model is developed to predict the stress-strain relation of ferrite phase steel under room temperature tension. This model is capable of capturing the grain size effect on both Lüders elongation and work-hardening behaviors of ferrite. The modeling results are extensively validated by experimental data.

  11. Thermomechanical deformation behavior of a dynamic strain aging alloy, Hastelloy X

    NASA Technical Reports Server (NTRS)

    Castelli, Michael G.; Miner, Robert V.; Robinson, David N.

    1992-01-01

    An experimental study was performed to identify the effects of dynamic strain aging (solute drag) and metallurgical instabilities under thermomechanical loading conditions. The study involved a series of closely controlled thermomechanical deformation tests on the solid-solution-strenghened nickel-base superalloy, Hastelloy X. This alloy exhibits a strong isothermal strain aging peak at approximately 600 C, promoted by the effects of solute drag and precipitation hardening. Macroscopic thermomechanical hardening trends are correlated with microstructural characteristics through the use of transmission electron microscopy. These observations are compared and contrasted with isothermal conditions. Thermomechanical behavior unique to the isothermal database is identified and discussed. The microstructural characteristics were shown to be dominated by effects associated with the highest temperature of the thermomechanical cycle. Results indicate that the deformation behavior of Hastelloy X is thermomechanically path dependent. In addition, guidance is given pertaining to deformation modeling in the context of macroscopic unified theory. An internal state variable is formulated to qualitatively reflect the isotropic hardening trends identified in the TMD experiments.

  12. Preconsolidation versus aging behavior of kaolinite clay

    SciTech Connect

    Athanasopoulos, G.A. )

    1993-06-01

    Results of resonant column tests were used to determine the effects of overconsolidation ratio (OCR) and of aging on the normalized rate of secondary increase N[sub G] of low-amplitude shear modulus G[sub 0] of a remolded kaolinite clay. The value of N[sub G] decreased approximately linearly with the logarithm of OCR and with the logarithm of duration of aging of the clay. The similarity of behavior provided a basis for establishing an equivalency between age-and-stress-induced equivalent overconsolidation for the clay in question. It was concluded that up to a certain limiting duration of aging the age-induced OCR increases linearly with elapsed time, whereas the effect starts diminishing for longer durations of aging. It is suggested that the results of similar studies on natural clay soils be used for predicting the long-term behavior of clays from the results of short-duration tests.

  13. Ageing behaviour of an Fe-20Ni-1.8Mn-1.6Ti-0.59Al (wt%) maraging alloy: clustering, precipitation and hardening

    SciTech Connect

    Pereloma, E.V. . E-mail: elena.pereloma@spme.monash.edu.au; Shekhter, A.; Miller, M.K.; Ringer, S.P.

    2004-11-08

    Changes in the solute distribution as well as the evolution of precipitation, microstructure and mechanical properties have been studied in an experimental maraging Fe-20Ni-1.8Mn-1.5Ti-0.59Al (wt%) alloy during ageing at 550 deg C. An initial hardening reaction within 5 s is reported, which is remarkable in terms of extent and rapidity. This strengthening was caused by the formation of complex multi-component atomic co-clusters containing primarily Ni-Ti-Al as well as some Mn. This cluster strengthened condition produced the optimum toughness observed throughout the ageing sequence. After 60 s ageing, the appearance of discrete precipitation of needle-shaped {eta}-Ni{sub 3}Ti particles was associated with a second rise in hardness towards an eventual peak at 600 s. This precipitation hardening was accompanied by an increase in tensile strength and a decrease in ductility. A reverse transformation of martensite to austenite occurs progressively during ageing and this contributes to the initial and secondary softening.

  14. Aging behavior and lifetime modeling for polycarbonate

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.

    2010-05-15

    In this paper, polycarbonate (PC) as a material candidate for solar absorber applications is investigated as to the aging behavior at different temperatures in air and water. The aging conditioning was performed in air in the temperature range from 120 to 140 C and in water between 70 and 95 C. Tensile tests were performed on unaged and aged PC film specimens at ambient temperature using strain-to-break values as a performance indicator for the degree of aging. For PC the effect of aging was found to strongly depend on the aging conditions. Activation energy based lifetime prediction models according to various methods described in the literature were applied. The activation energies and corresponding lifetime predictions for the temperature range from 40 to 60 C in water and from 90 to 110 C in air derived from these models are compared and interpreted as to their practical relevance. (author)

  15. Structural improvement of age-hardened gypsum-treated bauxite red mud waste using readily decomposable phyto-organics

    NASA Astrophysics Data System (ADS)

    Harris, Mark Anglin

    2009-02-01

    Several years (7) after incidental lithification by added gypsum, the effect of crushing and phyto-organics on some physical properties of red mud wastes (RMW) was examined under laboratory conditions. It was hypothesized that mechanically breaking up the hardened masses would increase their permeability. However, on the contrary, crushing these rock-hard masses into <2-mm particles did not increase permeability. A phyto-organic treatment on the other hand greatly improved permeability of the crushed entities such that infiltration rates increased from 0 to 10 cm/h. After 24 weeks of incubation, the structure of the newly formed phyto-organically treated gypsum-hardened RMW aggregates was also substantially improved over that of the controls, as a >3-fold increase in resistance to disintegration during wet sieving was exhibited by the phyto-organically treated samples. The increase in water infiltration by combining crushing with phyto-organic applications was ascribed to a decrease in particle dispersion, creating more stable clay clusters, which in turn stabilized channels and pores. Conversely, it was concluded that the singular crushing of gypsum-hardened bauxite waste in the waste dumps is potentially wasteful and ineffective.

  16. An Extended Age-Hardening Model for Al-Mg-Si Alloys Incorporating the Room-Temperature Storage and Cold Deformation Process Stages

    NASA Astrophysics Data System (ADS)

    Myhr, Ole Runar; Grong, Øystein; Schäfer, Carmen

    2015-12-01

    In this article, a new age-hardening model for Al-Mg-Si alloys is presented (named NaMo-Version 2), which takes into account the combined effect of cold deformation and prolonged room-temperature storage on the subsequent response to artificial aging. As a starting point, the original physical framework of NaMo-Version 1 is revived and used as a basis for the extension. This is permissible, since a more in-depth analysis of the underlying particle-dislocation interactions confirms previous expectations that the simplifying assumption of spherical precipitates is not crucial for the final outcome of the calculations, provided that the yield strength model is calibrated against experimental data. At the same time, the implementation of the Kampmann-Wagner formalism means that the different microstructure models can be linked together in a manner that enforces solute partitioning and competition between the different hardening phases which form during aging ( e.g., clusters, β″ and β'). In a calibrated form, NaMo-Version 2 exhibits a high degree of predictive power, as documented by comparison with experiments, using both dedicated nanostructure and yield strength data as a basis for the validation. Hence, the model is deemed to be well-suited for simulation of thermomechanical processing of Al-Mg-Si alloys involving cold-working operations like sheet forming and stretch bending in combination with heat treatment and welding.

  17. Behavioral Reputation: A Cross-Age Perspective.

    ERIC Educational Resources Information Center

    Zeller, Meg; Vannatta, Kathryn; Schafer, John; Noll, Robert B.

    2003-01-01

    Used the Revised Class Play measure to examine measurement of peer perceptions of behavioral reputation in elementary, middle, and high school environments. Found that data did not fit the original 3-factor structure; cross-loading of items and different patterns of association between subscales across age groups contributed to poor fit.…

  18. Precipitation hardening in 350 grade maraging steel

    SciTech Connect

    Viswanathan, U.K. . Radiometallurgy Div.); Dey, G.K. . Metallurgy Division); Asundi, M.K. )

    1993-11-01

    Evolution of microstructure in 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni[sub 3] (Ti, Mo) and Fe[sub 2]Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  19. Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions.

    PubMed

    Kurtz, S M; Pruitt, L A; Jewett, C W; Foulds, J R; Edidin, A A

    1999-08-01

    The mechanical behavior and evolution of crystalline morphology during large deformation of eight types of virgin and crosslinked ultra high molecular weight polyethylene (UHMWPE) were studied using the small punch test and transmission electron microscopy (TEM). We investigated the hypothesis that both radiation and chemical crosslinking hinder molecular mobility at large deformations, and hence promote strain hardening and molecular alignment during the multiaxial loading of the small punch test. Chemical crosslinking of UHMWPE was performed using 0.25% dicumyl peroxide (GHR 8110, GUR 1020 and 1050), and radiation crosslinking was performed using 150 kGy of electron beam radiation (GUR 1150). Crosslinking increased the ultimate load at failure and decreased the ultimate displacement of the polyethylenes during the small punch test. Crosslinking also increased the near-ultimate hardening behavior of the polyethylenes. Transmission electron microscopy was used to characterize the crystalline morphology of the bulk material, undeformed regions of the small punch test specimens, and deformed regions of the specimens oriented perpendicular and parallel to the punch direction. In contrast with the virgin polyethylenes, which showed only subtle evidence of lamellar alignment, the crosslinked polyethylenes exhibited enhanced crystalline lamellae orientation after the small punch test, predominantly in the direction parallel to the punch direction or deformation axis. Thus, the results of this study support the hypothesis that crosslinking promotes strain hardening during multiaxial loading because of increased resistance to molecular mobility at large deformations effected by molecular alignment. The data also illustrate the sensitivity of large deformation mechanical behavior and crystalline morphology to the method of crosslinking and resin of polyethylene. PMID:10458558

  20. Comparative Tensile Flow and Work-Hardening Behavior of 9 Pct Chromium Ferritic-Martensitic Steels in the Framework of the Estrin-Mecking Internal-Variable Approach

    NASA Astrophysics Data System (ADS)

    Choudhary, B. K.; Christopher, J.

    2016-06-01

    The comparative tensile flow and work-hardening behavior of P9 steel in two different product forms, normalized and tempered plate and thick section tube plate forging, and P91 steel were investigated in the framework of the dislocation dynamics based Estrin-Mecking (E-M) one-internal-variable approach. The analysis indicated that the flow behavior of P9 and P91 steels was adequately described by the E-M approach in a wide range of temperatures. It was suggested that dislocation dense martensite lath/cell boundaries and precipitates together act as effective barriers to dislocation motion in P9 and P91 steels. At room and intermediate temperatures, the evolution of the internal-state variable, i.e., the dislocation density with plastic strain, exhibited insignificant variations with respect to temperature. At high temperatures, a rapid evolution of dislocation density with plastic strain toward saturation with increasing temperature was observed. The softer P9 steel tube plate forging exhibited higher work hardening in terms of larger gains in the dislocation density and flow stress contribution from dislocations than the P9 steel plate and P91 steel at temperatures ranging from 300 K to 873 K (27 °C to 600 °C). The evaluation of activation energy suggests that the deformation is controlled by cross-slip of dislocations at room and intermediate temperatures, and climb of dislocations at high temperatures. The relative influence of initial microstructure on flow and work-hardening parameters associated with the E-M approach was discussed in the three temperature regimes displayed by P9 and P91 steels.

  1. Yield Behavior of Solution Treated and Aged Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Ring, Andrew J.; Baker, Eric H.; Salem, Jonathan A.; Thesken, John C.

    2014-01-01

    Post yield uniaxial tension-compression tests were run on a solution treated and aged (STA), titanium 6-percent aluminum 4-percent vanadium (Ti-6Al-4V) alloy to determine the yield behavior on load reversal. The material exhibits plastic behavior almost immediately on load reversal implying a strong Bauschinger effect. The resultant stress-strain data was compared to a 1D mechanics model and a finite element model used to design a composite overwrapped pressure vessel (COPV). Although the models and experimental data compare well for the initial loading and unloading in the tensile regime, agreement is lost in the compressive regime due to the Bauschinger effect and the assumption of perfect plasticity. The test data presented here are being used to develop more accurate cyclic hardening constitutive models for future finite element design analysis of COPVs.

  2. Dynamic strain aging influence on the cyclic behavior of Zircaloy-4

    SciTech Connect

    Armas, A.F.; Alvarez-Armas, I.; Moscato, G.

    1996-01-15

    Dynamic strain aging is a very important factor in the plastic deformation of zirconium and zirconium alloys and its aspects in uniaxial tensile tests have been the subject of several studies. Evidence of yield points in the stress-strain curve, appearance of plateaus or peaks in the flow stress-temperature diagram, discontinuous plastic flow, abnormal strain rate sensitivity have been reported in the literature. These anomalous mechanical behaviors were observed in these metals within the temperature range 473 to 823 K. The purpose of the present study is to examine the cyclic deformation characteristics of Zircaloy-4 in the temperature range 573--873 K and to show that the abnormal cyclic hardening observed in this material can be considered as a new aspect of dynamic strain aging.

  3. Microstructures, Mechanical Properties, and Strain Hardening Behavior of an Ultrahigh Strength Dual Phase Steel Developed by Intercritical Annealing of Cold-Rolled Ferrite/Martensite

    NASA Astrophysics Data System (ADS)

    Mazaheri, Y.; Kermanpur, A.; Najafizadeh, A.

    2015-07-01

    A dual phase (DP) steel was produced by a new process utilizing an uncommon cold-rolling and subsequent intercritical annealing of a martensite-ferrite duplex starting structure. Ultrafine grained DP steels with an average grain size of about 2 μm and chain-networked martensite islands were achieved by short intercritical annealing of the 80 pct cold-rolled duplex microstructure. The strength of the low carbon steel with the new DP microstructure was reached about 1300 MPa (140 pct higher than that of the as-received state, e.g., 540 MPa), without loss of ductility. Tensile testing revealed good strength-elongation balance for the new DP steels (UTS × UE ≈ 11,000 to 15,000 MPa pct) in comparison with the previous works and commercially used high strength DP steels. Two strain hardening stages with comparable exponents were observed in the Holloman analysis of all DP steels. The variations of hardness, strength, elongation, and strain hardening behavior of the specimens with thermomechanical parameters were correlated to microstructural features.

  4. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    NASA Astrophysics Data System (ADS)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-04-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  5. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    NASA Astrophysics Data System (ADS)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-06-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  6. Temperamental Origins of Child and Adolescent Behavior Problems: From Age Three to Age Fifteen.

    ERIC Educational Resources Information Center

    Caspi, Avshalom; And Others

    1995-01-01

    Assessed relationships between early temperament and behavior problems in a longitudinal study of 850 children from age 3 to 15. Temperament dimensions at ages 3 and 5 were correlated in theoretically coherent ways with behavior problems that were independently evaluated by parents and teachers at ages 9 and 11 and by parents as ages 13 and 15.…

  7. Birth Order and Maladaptive Behavior in School-Aged Children.

    ERIC Educational Resources Information Center

    Carmichael, Karla D.

    Drawing on Alfred Adler's theories on the effect of birth order on maladaptive behavior in children, this study focused on the relationship between birth order and the referral to counseling of school-aged children with maladaptive disorder. School-aged children (N=217) with academic or behavioral problems, ages 5 to 18, were referred to the staff…

  8. Microstructure and aging behavior of conventional and nanocrystalline aluminum-copper-magnesium alloys with scandium additions

    NASA Astrophysics Data System (ADS)

    Zuniga, Alejandro

    The influence of small amounts of scandium (0.15 and 0.3 wt.%) on the microstructure, aging behavior and mechanical properties of 2618 (Al-Cu-Mg-Fe-Ni) and C416 (Al-Cu-Mg-Ag-Mn) alloys was studied. It was observed the overall precipitation sequence and the general morphology of the aging curve were not affected by the addition of small amounts of Sc. It was also observed that a separate population of small Al3Sc particles improved the aging response and mechanical properties of low-Cu, low-Sc Al-Cu-Mg alloys, while the formation of Al5-8Cu7-4Sc particles resulted in a decrease of the mechanical properties in high-Cu Sc-containing alloys. The Sc-modified with the best aging response (2618 + 0.15 % Sc) was cryomilled in order to produce Al-Cu-Mg-Fe-Ni-Sc nanocrystalline powders. Bulk nanocrystalline samples were consolidated from the cryomilled powder using three different techniques: hot isostatic pressing and extrusion, spark plasma sintering, cold spraying. The influence of consolidation technique on the microstructure, aging behavior and mechanical properties was analyzed. The extruded and spark plasma sintered Al-Cu-Mg-Fe-Ni-Sc nanocrystalline samples presented a bimodal grain structure consisting of coarse-grained regions located at the inter-particle region, and nanocrystalline regions at the particle interiors. The aging behavior of the nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy was characterized by softening instead of hardening. This behavior was rationalized on the basis of changes in the precipitation processes that occur in the nanocrystalline state. On the other hand, the cold spray process promoted the formation of truly nanocrystalline coatings. The mechanisms influencing the coating formation of conventional and nanocrystalline Al-Cu-Mg-Fe-Ni-Sc samples were analyzed.

  9. Adulthood Predictors of Health Promoting Behavior in Later Aging

    ERIC Educational Resources Information Center

    Holahan, Carole K.; Suzuki, Rie

    2004-01-01

    This study investigated adulthood predictors of health-promoting behavior in later aging. The participants were 162 members of the Terman Study of the Gifted (Terman et al., 1925), who responded in 1999 at an average age of 86 to a mailout questionnaire which included questions concerning their positive health behavior. Adulthood variables were…

  10. Behavioral neuroscience of emotion in aging.

    PubMed

    Kaszniak, Alfred W; Menchola, Marisa

    2012-01-01

    Recent research on emotion and aging has revealed a stability of emotional experience from adulthood to older age, despite aging-related decrements in the perception and categorization of emotionally relevant stimuli. Research also shows that emotional expression remains intact with aging. In contrast, other studies provide evidence for an age-related decrease in autonomic nervous system physiological arousal, particularly in response to emotionally negative stimuli, and for shifts in central nervous system physiologic response to emotional stimuli, with increased prefrontal cortex activation and decreased amygdala activation in aging. Research on attention and memory for emotional information supports a decreased processing of negative emotional stimuli (i.e., a decrease in the negativity effect seen in younger adults), and a relative increase in the processing of emotionally positive stimuli (positivity effect). These physiological response and attentional/memory preference differences across increasingly older groups have been interpreted, within socioemotional selectivity theory, as reflecting greater motivation for emotion regulation with aging. According to this theory, as persons age, their perceived future time horizon shrinks, and a greater value is placed upon cultivating close, familiar, and meaningful relationships and other situations that give rise to positive emotional experience, and avoiding, or shifting attention from, those people and situations that are likely to elicit negative emotion. Even though there are central nervous system structural changes in emotion-relevant brain regions with aging, this shift in socioemotional selectivity, and perhaps the decreased autonomic nervous system physiological arousal of emotion with aging, facilitate enhanced emotion regulation with aging. PMID:21910076

  11. [Hardening of dental instruments].

    PubMed

    Gerasev, G P

    1981-01-01

    The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented. PMID:7300627

  12. Ethical Behavior in the Information Age

    ERIC Educational Resources Information Center

    Lincoln, Margaret

    2009-01-01

    In the months following AASL's 13th National Conference, the author has begun to process the new learning standards. The invitation to write about ethical behavior, identified as a Common Belief in the learning standards, has enabled her to reflect on how she is coming to grips with this important professional concept in her own practice. Analysis…

  13. Aggressive versus nonaggressive antisocial behavior: distinctive etiological moderation by age.

    PubMed

    Burt, S Alexandra; Neiderhiser, Jenae M

    2009-07-01

    Research has supported the existence of distinct behavioral patterns, demographic correlates, and etiologic mechanisms for aggressive (AGG) versus nonaggressive but delinquent (DEL) antisocial behavior. Though behavioral genetic studies have the potential to further crystallize these dimensions, inconsistent results have limited their contribution. These inconsistencies may stem in part from the limited attention paid to the impact of age. In the current study, the authors thus examined age-related etiological moderation of AGG and DEL antisocial behavior in a sample of 720 sibling pairs (ranging in age from 10 to 18 years) with varying degrees of genetic relatedness. Results reveal that the magnitude of genetic and environmental influences on AGG remained stable across adolescence. By contrast, genetic influences on DEL increased dramatically with age, whereas shared environmental influences decreased. Subsequent longitudinal analyses fully replicated these results. Such findings highlight etiological distinctions between aggression and delinquency, and offer insights into the expression of genetic influences during development. PMID:19586186

  14. Age and Employee Green Behaviors: A Meta-Analysis

    PubMed Central

    Wiernik, Brenton M.; Dilchert, Stephan; Ones, Deniz S.

    2016-01-01

    Recent economic and societal developments have led to an increasing emphasis on organizational environmental performance. At the same time, demographic trends are resulting in increasingly aging labor forces in many industrialized nations. Commonly held stereotypes suggest that older workers are less likely to be environmentally responsible than younger workers. To evaluate the degree to which such age differences are present, we meta-analyzed 132 independent correlations and 336 d-values based on 4676 professional workers from 22 samples in 11 countries. Contrary to popular stereotypes, age showed small positive relationships with pro-environmental behaviors, suggesting that older adults engaged in these workplace behaviors slightly more frequently. Relationships with age appeared to be linear for overall, Conserving, Avoiding Harm, and Taking Initiative pro-environmental behaviors, but non-linear trends were observed for Transforming and Influencing Others behaviors. PMID:26973550

  15. Children's Social Behavior in Relationship to Participation in Mixed-Age or Same-Age Classrooms.

    ERIC Educational Resources Information Center

    McClellan, Diane E.; Kinsey, Susan

    Research on the social and cognitive effects of grouping children in mixed-age versus same-age classrooms is gaining interest among practitioners and researchers. This investigation used a teacher rating scale to assess children's prosocial, aggressive, and friendship behaviors in mixed- and same-age classrooms. Confounding variables such as the…

  16. Behavior analysis and the study of human aging

    PubMed Central

    Derenne, Adam; Baron, Alan

    2002-01-01

    As the population of older adults continues to rise, psychologists along with other behavioral and social scientists have shown increasing interest in this age group. Although behavior analysts have contributed to research on aging, the focus has been on applications that remedy age-related deficits, rather than a concern with aging as a developmental process. In particular, there has been little interest in the central theoretical questions that have guided gerontologists. How does behavior change with advancing years, and what are the sources of those changes? We consider the possibility that this neglect reflects the long-standing commitment of behavior analysts to variables that can be experimentally manipulated, a requirement that excludes the key variable—age itself. We review the options available to researchers and present strategies that minimize deviations from the traditional features of behavior-analytic designs. Our comments are predicated on the view that aging issues within contemporary society are far too important for behavior analysts to ignore. PMID:22478383

  17. X-Ray Spectral and Timing Behavior of Scorpius X-1. Spectral Hardening during the Flaring Branch

    NASA Astrophysics Data System (ADS)

    Titarchuk, Lev; Seifina, Elena; Shrader, Chris

    2014-07-01

    We present an analysis of the spectral and timing properties of X-ray emission from the Z-source Sco X-1 during its evolution between the horizontal (HB) and flaring (FB) branches observed with the Rossi X-ray Timing Explorer during the 1996-2002 period. We find that the broadband (3-250 keV) energy spectra during all spectral states can be adequately reproduced by a model, consisting of two Comptonized components and an iron line. We suggest that the seed photons of kT s1 <~ 0.7 keV coming from the disk and of temperature kT s2 <~ 1.8 keV coming from the neutron star (NS) are each upscattered by hot electrons of a "Compton cloud" (hereafter the Comptb1 and Comptb2 components, respectively, which are associated with the similarly subscripted parameters). The photon power-law index Γ2 is almost constant (Γ2 ~ 2) for all spectral states. In turn, Γ1 demonstrates a two-phase behavior with the spectral state: Γ1 is quasi-constant at the level Γ1 ~ 2 for the HB-NB and Γ1 is less than 2, namely in the range of 1.3 < Γ1 < 2, when the source traces the FB. We also detect a decrease kT s2 from 1.8 keV to 0.7 keV during the FB. We interpret this apparent quasi-stability of the indices during the HB-NB in the framework of the model in which the spectrum is determined by the Comptonized thermal components. This effect established for the Comptonized spectral components of the Z-source Sco X-1 is similar to what was previously found in the atoll sources 4U 1728-34, GX 3+1 and 4U 1820-30 and the Z-source GX 340+0 through all spectral states. However, we interpret the index reduction phase detected during the FB in Sco X-1 within the framework of a model in which the spectrum at the FB is determined by high radiation pressure from the NS surface.

  18. X-ray spectral and timing behavior of Scorpius X-1. Spectral hardening during the flaring branch

    SciTech Connect

    Titarchuk, Lev; Seifina, Elena

    2014-07-10

    We present an analysis of the spectral and timing properties of X-ray emission from the Z-source Sco X-1 during its evolution between the horizontal (HB) and flaring (FB) branches observed with the Rossi X-ray Timing Explorer during the 1996-2002 period. We find that the broadband (3-250 keV) energy spectra during all spectral states can be adequately reproduced by a model, consisting of two Comptonized components and an iron line. We suggest that the seed photons of kT{sub s1} ≲ 0.7 keV coming from the disk and of temperature kT{sub s2} ≲ 1.8 keV coming from the neutron star (NS) are each upscattered by hot electrons of a 'Compton cloud' (hereafter the Comptb1 and Comptb2 components, respectively, which are associated with the similarly subscripted parameters). The photon power-law index Γ{sub 2} is almost constant (Γ{sub 2} ∼ 2) for all spectral states. In turn, Γ{sub 1} demonstrates a two-phase behavior with the spectral state: Γ{sub 1} is quasi-constant at the level Γ{sub 1} ∼ 2 for the HB–NB and Γ{sub 1} is less than 2, namely in the range of 1.3 < Γ{sub 1} < 2, when the source traces the FB. We also detect a decrease kT{sub s2} from 1.8 keV to 0.7 keV during the FB. We interpret this apparent quasi-stability of the indices during the HB–NB in the framework of the model in which the spectrum is determined by the Comptonized thermal components. This effect established for the Comptonized spectral components of the Z-source Sco X-1 is similar to what was previously found in the atoll sources 4U 1728-34, GX 3+1 and 4U 1820-30 and the Z-source GX 340+0 through all spectral states. However, we interpret the index reduction phase detected during the FB in Sco X-1 within the framework of a model in which the spectrum at the FB is determined by high radiation pressure from the NS surface.

  19. Helium Release Behavior of Aged Titanium Tritides

    SciTech Connect

    SHANAHAN, KIRKL.

    2004-07-27

    One sample of bulk Ti has been loaded with a 50 per cent / 50 per cent deuterium/tritium mixture and statically aged for 6.5 years. Thermal desorption of the sample shows an initial release of hydrogen isotopes followed by 3He release. Subsequent D2 loading/desorption was used to quantify the trapped tritium heel. The sample shows an excess hydrogen capacity as a second thermal desorption peak that partially disappears and shifts with annealing at 923-973K. The main hydrogen desorption peak also shifts to higher temperature, indicating a partial reversal of the tritium-decay induced damage by annealing.

  20. The Child Behavior Profile: I. Boys Aged 6-11.

    ERIC Educational Resources Information Center

    Achenbach, Thomas M.

    1978-01-01

    Reports standardization of the Child Behavior Checklist for boys aged 6-11. Analysis of CBCLs of disturbed boys yielded behavior problem scales labeled schizoid, depressed, uncommunicative, obsessive-compulsive, somatic complaints, social withdrawal, hyperactive, aggressive, and delinquent. Second-order factors are Internalizing and Externalizing.…

  1. Walnuts improve neuronal and behavioral function in aging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction Walnuts are rich in polyunsaturated fatty acids (PUFAs) and polyphenols which have been shown to improve neurochemical and behavioral function. Objectives This study investigated the mechanisms associated with age-related behavioral improvements in rats fed diets supplemented with walnu...

  2. An Adolescent Age Group Approach to Examining Youth Risk Behaviors.

    ERIC Educational Resources Information Center

    Oman, Roy F.; McLeroy, Kenneth R.; Vesely, Sara; Aspy, Cheryl B.; Smith, David W.; Penn, David A.

    2002-01-01

    Investigated relationships among youth risk behaviors and demographic factors. Data on risk behaviors (delinquency, truancy, weapon carrying, fighting, sexuality, substance use, demographics, and family structure) were compared within specific demographic factors and by age group for diverse inner-city adolescents. Survey and interview data…

  3. Nonequilibrium grain-boundary segregation and ductile-brittle-ductile transition in Fe-Mn-Ni-Ti age-hardening alloy

    SciTech Connect

    Heo, N.H.

    1996-10-01

    Nonequilibrium segregation kinetics of alloying elements and a ductile-brittle-ductile transition behavior have been investigated in an Fe-8.4Mn-7.4Ni-1.7Ti alloy. The alloy experienced a ductile-brittle-ductile (DBD) transition during isothermal aging. In the brittle region, the alloy showed a decrease in intergranular fracture strength and a subsequent increase with aging time. This is due to the segregation of titanium to the grain boundaries and its desegregation into the matrix. The intergranular fracture strength was higher on the zero tensile elongation finish curve than on the start curve. This is because the grain-boundary segregation level of titanium is relatively lower on the finish curve. The lowest intergranular fracture strength increased with increasing aging temperature, which was attributed to a lower grain-boundary segregation level of titanium at higher temperature. Manganese caused an overall reduction in intergranular fracture strength and, as a result, the delayed occurrence of the zero tensile elongation (ZTE) finish curve in a temperature and long-time plot.

  4. Aging Behavior and Performance Projections for a Polysulfide Elastomer

    SciTech Connect

    Celina, Mathias C.; Giron, Nicholas Henry; Quintana, Adam

    2015-05-01

    The accelerated aging behavior and aging state of a 30 year old field retrieved polysulfide elastomer was examined. The material is used as an environmental thread sealant for a stainless steel bolt in a steel threaded insert in an aluminum assembly. It is a two component curable polysulfide elastomer that is commercially available in a similar formulation as was applied 30 years ago. The primary goal of this study was to establish if aging over 30 years under moderate aging conditions (mostly ambient temperature and humidity) resulted in significant property changes, or if accelerated aging could identify developing aging pathways which would prevent the extended use of this material. The aging behavior of this material was examined in three ways: A traditional accelerated thermo-oxidative aging study between 95 to 140°C which focused on physical and chemical properties changes, an evaluation of the underlying oxidation rates between RT and 125°C, and an assessment of the aging state of a small 30 year old sample. All three data sets were used to establish aging characteristics, their time evolution, and to extrapolate the observed behavior to predict performance limits at RT. The accelerated aging study revealed a relatively high average activation energy of ~130 kJ/mol which gives overconfident performance predictions. Oxidation rates showed a decreasing behavior with aging time and a lower E a of ~84 kJ/mol from time - temperature superposition , but also predicted sufficient additional performance at RT. Consistent with these projections for extended RT performance, only small changes were observed for the 30 year old material. Extrapolations using this partially aged material also predict ongoing use as a viable option. Unexpected RT degradation could only develop into a concern should the oxidation rate not trend lower over time as was observed at elevated temperature. Considering all data acquired in this limited aging study , there are no immediately

  5. Prosocial Behavior Increases with Age across Five Economic Games

    PubMed Central

    Matsumoto, Yoshie; Yamagishi, Toshio; Li, Yang; Kiyonari, Toko

    2016-01-01

    Ontogenic studies of human prosociality generally agree on that human prosociality increases from early childhood through early adulthood; however, it has not been established if prosociality increases beyond early adulthood. We examined a sample of 408 non-student residents from Tokyo, Japan, who were evenly distributed across age (20–59) and sex. Participants played five economic games each separated by a few months. We demonstrated that prosocial behavior increased with age beyond early adulthood and this effect was shown across all five economic games. A similar, but weaker, age-related trend was found in one of three social value orientation measures of prosocial preferences. We measured participants’ belief that manipulating others is a wise strategy for social success, and found that this belief declined with age. Participants’ satisfaction with the unilateral exploitation outcome of the prisoner’s dilemma games also declined with age. These two factors—satisfaction with the DC outcome in the prisoner’s dilemma games and belief in manipulation—mediated the age effect on both attitudinal and behavioral prosociality. Participants’ age-related socio-demographic traits such as marriage, having children, and owning a house weakly mediated the age effect on prosociality through their relationships with satisfaction with the DC outcome and belief in manipulation. PMID:27414803

  6. Prosocial Behavior Increases with Age across Five Economic Games.

    PubMed

    Matsumoto, Yoshie; Yamagishi, Toshio; Li, Yang; Kiyonari, Toko

    2016-01-01

    Ontogenic studies of human prosociality generally agree on that human prosociality increases from early childhood through early adulthood; however, it has not been established if prosociality increases beyond early adulthood. We examined a sample of 408 non-student residents from Tokyo, Japan, who were evenly distributed across age (20-59) and sex. Participants played five economic games each separated by a few months. We demonstrated that prosocial behavior increased with age beyond early adulthood and this effect was shown across all five economic games. A similar, but weaker, age-related trend was found in one of three social value orientation measures of prosocial preferences. We measured participants' belief that manipulating others is a wise strategy for social success, and found that this belief declined with age. Participants' satisfaction with the unilateral exploitation outcome of the prisoner's dilemma games also declined with age. These two factors-satisfaction with the DC outcome in the prisoner's dilemma games and belief in manipulation-mediated the age effect on both attitudinal and behavioral prosociality. Participants' age-related socio-demographic traits such as marriage, having children, and owning a house weakly mediated the age effect on prosociality through their relationships with satisfaction with the DC outcome and belief in manipulation. PMID:27414803

  7. Privacy and human behavior in the age of information.

    PubMed

    Acquisti, Alessandro; Brandimarte, Laura; Loewenstein, George

    2015-01-30

    This Review summarizes and draws connections between diverse streams of empirical research on privacy behavior. We use three themes to connect insights from social and behavioral sciences: people's uncertainty about the consequences of privacy-related behaviors and their own preferences over those consequences; the context-dependence of people's concern, or lack thereof, about privacy; and the degree to which privacy concerns are malleable—manipulable by commercial and governmental interests. Organizing our discussion by these themes, we offer observations concerning the role of public policy in the protection of privacy in the information age. PMID:25635091

  8. Effects of long-term thermal aging on the stress corrosion cracking behavior of cast austenitic stainless steels in simulated PWR primary water

    NASA Astrophysics Data System (ADS)

    Li, Shilei; Wang, Yanli; Wang, Hui; Xin, Changsheng; Wang, Xitao

    2016-02-01

    The stress corrosion cracking (SCC) behavior of cast austenitic stainless steels of unaged and thermally aged at 400 °C for as long as 20,000 h were studied by using a slow strain rate testing (SSRT) system. Spinodal decomposition in ferrite during thermal aging leads to hardening in ferrite and embrittlement of the SSRT specimen. Plastic deformation and thermal aging degree have a great influence on the oxidation rate of the studied material in simulated PWR primary water environments. In the SCC regions of the aged SSRT specimen, the surface cracks, formed by the brittle fracture of ferrite phases, are the possible locations for SCC. In the non-SCC regions, brittle fracture of ferrite phases also occurs because of the effect of thermal aging embrittlement.

  9. [Organic factors in behavior disorders in the developmental age].

    PubMed

    Mitrović, D; Popov, I; Nikolić, V

    1990-01-01

    The problem of bad behavior in the young is as old as the written history of mankind. It is always a current problem in a practical and theoretical sense as well. While everyday life is filled with various forms of criminal offense, drug addiction, the forming of gangs-especially in dynamic societies, theoretical opinions tend to oscillate between biological factors and the psychological-social ones which are always unsuitable for a person in the course of its development. The authors have presented a review of the basic theoretical directions, and after that the results of their own research. Children with behavior disorders were investigated: parallely by psychological-psychiatric investigation as well as with an up-to-date biological approach, examining subclinical semiotics, EEG and REG. On the basis of these comparisons we have come to the following principal opinions: the suggested psycho-neuro-vegetative subclinical syndrome, recommended by the same authors, does not take the behavior disorder upon itself. Also, not every behavior disorder includes the obligatory psycho-neuro-vegetative subclinical syndrome (PNVSS). Nevertheless, PNVSS presents a risk factor for behavior disorder, in the case that the personality in development is growing up under unfavorable psycho-social conditions. Finally, in the younger ages PNVSS, by its primary features, determines the behavior disorder also, while at an older age (after 11) behavior has all the more of an asocial and antisocial character. PMID:2233559

  10. The effects of gender and age on health related behaviors

    PubMed Central

    Deeks, Amanda; Lombard, Catherine; Michelmore, Janet; Teede, Helena

    2009-01-01

    Background Lifestyle-related diseases, including diabetes, cardiovascular disease, and some cancers represent the greatest global health threat. Greater insight into health needs and beliefs, using broad community samples, is vital to reduce the burden of chronic disease. This study aimed to investigate gender, age, screening practices, health beliefs, and perceived future health needs for healthy ageing. Methods Random probability sampling using self-completion surveys in 1456 adults residing in Australia. Results Screening behaviors were associated with gender and age. Men and women >51 years were more likely (27%) to have screening health checks than those <50 years (2%). Factors nominated to influence health were lifestyle (92%), relationships (82%), and environment (80%). Women were more likely to nominate preparedness to have an annual health check, willingness to seek advice from their medical practitioner and to attend education sessions. Numerous health fears were associated with ageing, however participants were more likely to have a financial (72%) rather than a health plan (42%). More women and participants >51 years wanted information regarding illness prevention than men or those aged <30 years. Conclusion Age and gender are associated with health related behaviors. Optimal health is perceived as a priority, yet often this perception is not translated into preventative action. These findings will inform future research and policy makers as we strive towards a healthier ageing society and the prevention of chronic disease. PMID:19563685

  11. Reward components of feeding behavior are preserved during mouse aging

    PubMed Central

    Harb, Mazen R.; Sousa, Nuno; Zihl, Joseph; Almeida, Osborne F. X.

    2014-01-01

    Eating behavior depends on associations between the sensory and energetic properties of foods. Healthful balance of these factors is a challenge for industrialized societies that have an abundance of food, food choices and food-related cues. Here, we were interested in whether appetitive conditioning changes as a function of age. Operant and pavlovian conditioning experiments (rewarding stimulus was a palatable food) in male mice (aged 3, 6, and 15 months) showed that implicit (non-declarative) memory remains intact during aging. Two other essential components of eating behavior, motivation and hedonic preference for rewarding foods, were also found not to be altered in aging mice. Specifically, hedonic responding by satiated mice to isocaloric foods of differing sensory properties (sucrose, milk) was similar in all age groups; importantly, however, this paradigm disclosed that older animals adjust their energy intake according to energetic need. Based on the assumption that the mechanisms that control feeding are conserved across species, it would appear that overeating and obesity in humans reflects a mismatch between ancient physiological mechanisms and today's cue-laden environment. The implication of the present results showing that aging does not impair the ability to learn stimulus-food associations is that the risk of overeating in response to food cues is maintained through to old age. PMID:25278876

  12. X-Ray Diffraction Profile Analysis for Characterizing Isothermal Aging Behavior of M250 Grade Maraging Steel

    NASA Astrophysics Data System (ADS)

    Mahadevan, S.; Jayakumar, T.; Rao, B. P. C.; Kumar, Anish; Rajkumar, K. V.; Raj, Baldev

    2008-08-01

    X-ray diffraction (XRD) studies were carried out to characterize aging behavior of M250 grade maraging steel samples subjected to isothermal aging at 755 K for varying durations of 0.25, 1, 3, 10, 40, 70, and 100 hours. Earlier studies had shown typical features of precipitation hardening, wherein the hardness increased to a peak value due to precipitation of intermetallics and decreased upon further aging (overaging) due to reversion of martensite to austenite. Intermetallic precipitates, while coherent, are expected to increase the microstrain in the matrix. Hence, an attempt has been made in the present study to understand the microstructural changes in these samples using XRD line profile analysis. The anisotropic broadening with diffraction angle observed in the simple Williamson Hall (WH) plot has been addressed using the modified WH (mWH) approach, which takes into account the contrast caused by dislocations on line profiles, leading to new scaling factors in the WH plot. The normalized mean square strain and crystallite size estimated from mWH have been used to infer early precipitation and to characterize aging behavior. The normalized mean square strain has been used to determine the Avrami exponent in the Johnson Mehl Avrami (JMA) equation, which deals with the kinetics of precipitation. The Avrami exponent thus determined has matched well with values found by other methods, as reported in literature.

  13. Age Sensitivity of Behavioral Tests and Brain Substrates of Normal Aging in Mice

    PubMed Central

    Kennard, John A.; Woodruff-Pak, Diana S.

    2011-01-01

    Knowledge of age sensitivity, the capacity of a behavioral test to reliably detect age-related changes, has utility in the design of experiments to elucidate processes of normal aging. We review the application of these tests in studies of normal aging and compare and contrast the age sensitivity of the Barnes maze, eyeblink classical conditioning, fear conditioning, Morris water maze, and rotorod. These tests have all been implemented to assess normal age-related changes in learning and memory in rodents, which generalize in many cases to age-related changes in learning and memory in all mammals, including humans. Behavioral assessments are a valuable means to measure functional outcomes of neuroscientific studies of aging. Highlighted in this review are the attributes and limitations of these measures in mice in the context of age sensitivity and processes of brain aging. Attributes of these tests include reliability and validity as assessments of learning and memory, well-defined neural substrates, and sensitivity to neural and pharmacological manipulations and disruptions. These tests engage the hippocampus and/or the cerebellum, two structures centrally involved in learning and memory that undergo functional and anatomical changes in normal aging. A test that is less well represented in studies of normal aging, the context pre-exposure facilitation effect (CPFE) in fear conditioning, is described as a method to increase sensitivity of contextual fear conditioning to changes in the hippocampus. Recommendations for increasing the age sensitivity of all measures of normal aging in mice are included, as well as a discussion of the potential of the under-studied CPFE to advance understanding of subtle hippocampus-mediated phenomena. PMID:21647305

  14. 42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN AND TEMPER THE NAILS; WEST TUBES IN FOREGRPUND AND DRAWBACK TUBE IN THE CENTER - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

  15. Respiratory and sniffing behaviors throughout adulthood and aging in mice

    PubMed Central

    Wesson, Daniel W.; Varga-Wesson, Adrienn G.; Borkowski, Anne H.; Wilson, Donald A.

    2011-01-01

    Orienting responses are physiological and active behavioral reactions evoked by novel stimulus perception and are critical for survival. We explored whether odor orienting responses are impacted throughout both adulthood and normal and pathological aging in mice. Novel odor investigation (including duration and bout numbers) and its subsequent habituation as assayed in the odor habituation task were preserved in adult C57BL/6J mice up to 12mo of age with <6% variability between age groups in investigation time. Separately, using whole-body plethysmography we found that both spontaneous respiration and odor-evoked sniffing behaviors were strikingly preserved in wildtype (WT) mice up to 26mo of age. In contrast, mice accumulating amyloid-β protein in the brain by means of overexpressing mutations in the human amyloid precursor protein gene (APP) showed preserved spontaneous respiration up to 12mo, but starting at 14mo showed significant differences from WT. Similar to WTs, odor-evoked sniffing was not impacted in APP mice up to 26mo. These results show that odor-orienting responses are minimally impacted throughout aging in mice, and suggest that the olfactomotor network is mostly spared of insults due to aging. PMID:21524667

  16. An assessment of behavioral aging in the Mongolian gerbil.

    PubMed

    Spangler, E L; Hengemihle, J; Blank, G; Speer, D L; Brzozowski, S; Patel, N; Ingram, D K

    1997-01-01

    Male Mongolian gerbils (Meriones unguiculatus) 14-54 months old (n = 77) were evaluated in a battery of psychomotor (open field, locomotor, and runwheel activity, rotorod performance) and learning (one-way active avoidance in a straight runway and in 14-unit T-maze performance) tests. Body weight and seizure activity were also monitored. According to linear regression analysis, runwheel activity decreased with age; and the number of errors in the 14-unit T-maze increased as a function of age (ps < 0.05). None of the other behavioral measures or body weight were significantly correlated with age. This gerbil strain (Tumblebrook Farms; West Brookfield, MA) tended to be very prone to seizures with 64% of the gerbils experiencing at least one seizure while being tested. Seizures tended to occur when the gerbil was exposed to a novel situation (e.g., initial weighing, placement on the rotorod). An age-related decline in some aspects of psychomotor and learning performance was observed, suggesting the gerbil as an additional mammalian model of aging. The high incidence of seizure activity presented a complicating and confounding variable to the interpretation of the results of the behavioral tests used in the present study. Interventions to control seizure activity (e.g., systematic, controlled breeding; adaptation to apparati) in this model will likely increase its viability as a mammalian model of aging. PMID:9785096

  17. Age differences in the impact of employment on antisocial behavior.

    PubMed

    Monahan, Kathryn C; Steinberg, Laurence; Cauffman, Elizabeth

    2013-01-01

    While research suggests that working more than 20 hr weekly is associated with greater antisocial behavior among middle- and upper-class youth, some have argued that employment benefits at-risk youth and leads to desistance from crime among youthful offenders. This study investigates the relation between hours worked, school attendance, and employment characteristics on antisocial behavior in a sample of approximately 1,300 juvenile offenders (ages 14-17 at baseline) tracked over 5 years. The combinations of high-intensity employment and irregular school attendance, unemployment and irregular school attendance, and unemployment and not being enrolled in school are associated with significantly greater antisocial behavior, particularly during early adolescence. High-intensity employment diminishes antisocial behavior only when accompanied by attending school. PMID:23278700

  18. Modeling of Irradiation Hardening of Polycrystalline Materials

    SciTech Connect

    Li, Dongsheng; Zbib, Hussein M.; Garmestani, Hamid; Sun, Xin; Khaleel, Mohammad A.

    2011-09-14

    High energy particle irradiation of structural polycrystalline materials usually produces irradiation hardening and embrittlement. The development of predict capability for the influence of irradiation on mechanical behavior is very important in materials design for next generation reactors. In this work a multiscale approach was implemented to predict irradiation hardening of body centered cubic (bcc) alpha-iron. The effect of defect density, texture and grain boundary was investigated. In the microscale, dislocation dynamics models were used to predict the critical resolved shear stress from the evolution of local dislocation and defects. In the macroscale, a viscoplastic self-consistent model was applied to predict the irradiation hardening in samples with changes in texture and grain boundary. This multiscale modeling can guide performance evaluation of structural materials used in next generation nuclear reactors.

  19. Behavioral Assessment of the Aging Mouse Vestibular System

    PubMed Central

    Tung, Victoria W. K.; Burton, Thomas J.; Dababneh, Edward; Quail, Stephanie L.; Camp, Aaron J.

    2014-01-01

    Age related decline in balance performance is associated with deteriorating muscle strength, motor coordination and vestibular function. While a number of studies show changes in balance phenotype with age in rodents, very few isolate the vestibular contribution to balance under either normal conditions or during senescence. We use two standard behavioral tests to characterize the balance performance of mice at defined age points over the lifespan: the rotarod test and the inclined balance beam test. Importantly though, a custom built rotator is also used to stimulate the vestibular system of mice (without inducing overt signs of motion sickness). These two tests have been used to show that changes in vestibular mediated-balance performance are present over the murine lifespan. Preliminary results show that both the rotarod test and the modified balance beam test can be used to identify changes in balance performance during aging as an alternative to more difficult and invasive techniques such as vestibulo-ocular (VOR) measurements. PMID:25045963

  20. Age-Related Changes in Demand-Withdraw Communication Behaviors.

    PubMed

    Holley, Sarah R; Haase, Claudia M; Levenson, Robert W

    2013-08-01

    Demand-withdraw communication is a set of conflict-related behaviors in which one partner blames or pressures while the other partner withdraws or avoids. The present study examined age-related changes in these behaviors longitudinally over the course of later life stages. One hundred twenty-seven middle-aged and older long-term married couples were observed at 3 time points across 13 years as they engaged in a conversation about an area of relationship conflict. Husbands' and wives' demand-withdraw behaviors (i.e., blame, pressure, withdrawal, avoidance) were objectively rated by trained coders at each time point. Data were analyzed using dyad-level latent growth curve models in a structural equation modeling framework. For both husbands and wives, the results showed a longitudinal pattern of increasing avoidance behavior over time and stability in all other demand and withdraw behaviors. This study supports the notion that there is an important developmental shift in the way that conflict is handled in later life. PMID:23913982

  1. Age-Related Changes in Demand–Withdraw Communication Behaviors

    PubMed Central

    Holley, Sarah R.; Haase, Claudia M.; Levenson, Robert W.

    2013-01-01

    Demand–withdraw communication is a set of conflict-related behaviors in which one partner blames or pressures while the other partner withdraws or avoids. The present study examined age-related changes in these behaviors longitudinally over the course of later life stages. One hundred twenty-seven middle-aged and older long-term married couples were observed at 3 time points across 13 years as they engaged in a conversation about an area of relationship conflict. Husbands’ and wives’ demand–withdraw behaviors (i.e., blame, pressure, withdrawal, avoidance) were objectively rated by trained coders at each time point. Data were analyzed using dyad-level latent growth curve models in a structural equation modeling framework. For both husbands and wives, the results showed a longitudinal pattern of increasing avoidance behavior over time and stability in all other demand and withdraw behaviors. This study supports the notion that there is an important developmental shift in the way that conflict is handled in later life. PMID:23913982

  2. Aging behavior of polymeric solar absorber materials: Aging on the component level

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.; Meir, M.; Rekstad, J.

    2010-03-15

    Within this study, the aging behavior of a PPE + PS absorber material was investigated on the absorber component level. To indicate aging, characteristic mechanical values were determined by indentation tests of specimens taken from components and exposed to laboratory aging (140 C in air, 80 C in water) and service near outdoor aging conditions (stagnation in northern climate). In addition to the mechanical tests, the unaged and aged specimens were also characterized thermo-analytically via differential scanning calorimetry (DSC). The results indicate that reductions in both characteristic mechanical values of the indentation tests, i.e., load of the first transition and ultimate indentation, reflect at least some physical aging although chemical aging may also be of importance based on previous analytical investigations of laboratory aged polymer films. While laboratory aging in air at 140 C and service exposure at a test facility in Oslo (N) under stagnation conditions led to a significant reduction in the mechanical indentation resistance, no influence of laboratory aging in water at 80 C on the mechanical behavior of the absorber sheet was found. Depending on the ultimate failure criterion applied (reduction of characteristic mechanical values to 80% and 50%, respectively), the technical service life found for hot air laboratory and stagnation service conditions was found to be less than 51 and 159 h, respectively. As these durations are significantly below the estimated stagnation conditions accumulated in the desired operation lifetime for such a collector, the PPE + PS type investigated does not seem to be a proper material candidate for solar thermal absorbers. Finally, based on the results obtained, a relation between laboratory aging time in air at 140 C and cumulated irradiation energy during exposure on the test facility in Oslo was established. (author)

  3. Deformation in metals after low temperature irradiation: Part II - Irradiation hardening, strain hardening, and stress ratios

    SciTech Connect

    Byun, Thak Sang; Li, Meimei

    2008-03-01

    Effects of irradiation at temperatures 200oC on tensile stress parameters are analyzed for dozens of bcc, fcc, and hcp pure metals and alloys, focusing on irradiation hardening, strain hardening, and relationships between the true stress parameters. Similar irradiation-hardening rates are observed for all the metals irrespective of crystal type; typically, the irradiation-hardening rates are large, in the range 100 - 1000 GPa/dpa, at the lowest dose of <0.0001 dpa and decrease with dose to a few tens of MPa/dpa or less at about 10 dpa. However, average irradiation-hardening rates over the dose range of 0 dpa − (the dose to plastic instability at yield) are considerably lower for stainless steels due to their high uniform ductility. It is shown that whereas low temperature irradiation increases the yield stress, it does not significantly change the strain-hardening rate of metallic materials; it decreases the fracture stress only when non-ductile failure occurs. Such dose independence in strain hardening behavior results in strong linear relationships between the true stress parameters. Average ratios of plastic instability stress to unirradiated yield stress are about 1.4, 3.9, and 1.3 for bcc metals (and precipitation hardened IN718 alloy), annealed fcc metals (and pure Zr), and Zr-4 alloy, respectively. Ratios of fracture stress to plastic instability stress are calculated to be 2.2, 1.7, and 2.1, respectively. Comparison of these values confirms that the annealed fcc metals and other soft metals have larger uniform ductility but smaller necking ductility when compared to other materials.

  4. Behavior Management for School Aged Children with ADHD

    PubMed Central

    Pfiffner, Linda J.; Haack, Lauren M.

    2014-01-01

    Synopsis Behavior management treatments are the most commonly used nonpharmacological approaches for treating ADHD and associated impairments. This review focuses on behavioral parent training interventions for school age children in the home setting and adjunctive treatments developed to extend effects across settings. The underlying theoretical basis and content of these interventions are described. Empirical support includes numerous randomized clinical trials, systematic reviews, and meta-analyses showing positive effects of these interventions on child compliance, ADHD symptoms and impairments, parent-child interactions, parenting and parenting stress. These studies support categorization of behavior management treatment as a well-established, evidence-based treatment for ADHD. Factors for consideration in clinical decision-making and future directions for research are provided. PMID:25220083

  5. RHOBOT: Radiation hardened robotics

    SciTech Connect

    Bennett, P.C.; Posey, L.D.

    1997-10-01

    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

  6. Precipitation hardening austenitic superalloys

    DOEpatents

    Korenko, Michael K.

    1985-01-01

    Precipitation hardening, austenitic type superalloys are described. These alloys contain 0.5 to 1.5 weight percent silicon in combination with about 0.05 to 0.5 weight percent of a post irradiation ductility enhancing agent selected from the group of hafnium, yttrium, lanthanum and scandium, alone or in combination with each other. In addition, when hafnium or yttrium are selected, reductions in irradiation induced swelling have been noted.

  7. Nuclear effects hardened shelters

    NASA Astrophysics Data System (ADS)

    Lindke, Paul

    1990-11-01

    The Houston Fearless 76 Government Projects Group has been actively engaged for more than twenty-five years as a sub-contractor and currently as a prime contractor in the design, manufacture, repair and logistics support of custom mobile ground stations and their equipment accommodations. Other associated products include environmental control units (ECU's), mobilizers for shelters and a variety of mobile power generation units (MPU's). Since 1984, Houston Fearless 76 has designed and manufactured four 8' x 8' x 22' nuclear hardened mobile shelters. These shelters were designed to contain electronic data processing/reduction equipment. One shelter is currently being operated by the Air Force as a Defense Intelligence Agency (DIA) approved and certified Special Corrpartmented Information Facility (SCIF). During the development and manufacturing process of the shelters, we received continual technical assistance and design concept evaluations from Science Applications International Corporation (SAIC) Operations Analysis and Logistics Engineering Division and the Nondestructive Inspection Lab at McClellan AFB. SAIC was originally employed by the Air Force to design the nuclear hardening specifications applied to these shelters. The specific levels of hardening to which the shelters were designed are classified and will not be mentioned during this presentation.

  8. Aging and generational effects on drinking behaviors in men: results from the normative aging study.

    PubMed Central

    Glynn, R J; Bouchard, G R; LoCastro, J S; Laird, N M

    1985-01-01

    The effects of aging on alcohol consumption behaviors are unclear because of confounding with period and cohort effects. In 1973, 1,859 male participants in the Normative Aging Study, born between 1892 and 1945, described their drinking behaviors by responding to a mailed questionnaire. In 1982, 1,713 of the participants in this study responded to a similar questionnaire. We used multivariate techniques, adjusting regression coefficients for the correlations between repeated responses of the same individuals, to assess the effects of birth cohort and aging on mean alcohol consumption level, on the prevalence of problems with drinking, and on the prevalence of averaging three or more drinks per day. Older men drank significantly less than younger men at both times yet there was no tendency for men to decrease their consumption levels over time. Each successively older birth cohort had a prevalence of problems with drinking estimated to be 0.037 lower than the prevalence of the next youngest cohort (95 per cent confidence interval: 0.029-0.045), yet there was no decrease in drinking problems over nine years. Interpretation of these findings requires consideration of the changes in attitudes as well as the increases in per capita consumption occurring in the United States throughout the 1970s. Results suggest that aging is not as important a factor in changes in drinking behaviors as generational or attitudinal changes. PMID:4061714

  9. Neuropathic pain in aged rats: behavioral responses and astrocytic activation.

    PubMed

    Stuesse, S L; Crisp, T; McBurney, D L; Schechter, J B; Lovell, J A; Cruce, W L

    2001-03-01

    We used the Bennett and Xie (1988) model of chronic neuropathic pain to study the effect of age on thermal and tactile sensitivity and on astrocytic activation in the dorsal horn of the spinal cord after nerve injury. Fischer 344 FBNF1 hybrid rats in three age groups, 4-6, 14-16, and 24-26 months, were studied. Rats were either unligated (day 0, control) or the left sciatic nerve was loosely ligated to cause a chronic constriction injury (CCI). CCI causes a neuropathic pain condition characterized by tactile allodynia and thermal hyperalgesia. Rats were behaviorally assessed for tactile and thermal sensitivity of their ligated and unligated hind paws up to 35 days postligation. Rats were sacrificed before or at various days postligation, and activated astrocytes were identified at the L4-L5 levels of their spinal cords by use of an antibody to glial fibrillary acid protein (GFAP). The number of GFAP-ir astrocytes in the dorsal horn of the spinal cord in the control, uninjured condition decreased with age (P < or = 0.001) but increased after CCI in all three age groups. After CCI, astrocytic activation in the cord was less robust in aged rats than in younger ones (P < or = 0.01). Not all the CCI rats displayed hyperalgesia to touch and to heat. Rats with an increased sensitivity to heat had increased levels of GFAP-ir in their cords; however, rats with decreased thermal sensitivity also displayed increased GFAP-ir. Thus the presence of activated astrocytes was not correlated with a single behavioral manifestation of neuropathic pain. PMID:11315551

  10. Age-concordant and age-discordant sexual behavior among gay and bisexual male adolescents.

    PubMed

    Bruce, Douglas; Harper, Gary W; Fernández, M Isabel; Jamil, Omar B

    2012-04-01

    There is evidence that risks for HIV and sexually transmitted infections among adolescent females are higher for those with older male sexual partners. Yet, little empirical research has been conducted with male adolescents who engage in sexual activity with older men. In this article, we summarize in a number of ways the range of sexual activity reported by an ethnically diverse sample of 200 gay and bisexual male youth (15-22 years old) in Chicago and Miami. A general pattern of progression from oral sex with men to both receptive and insertive anal sex with men appeared to characterize the sample during their adolescence. Further, there appeared to be a high degree of "versatile" positioning among the sexually active gay and bisexual young men, in both age-discrepant and age-concordant dyads. Risk analysis revealed having primarily age-concordant partners to be a significant predictor of sexual risk behavior. HIV risk among young gay and bisexual men engaging in sexual activity with older men may occur not only within a distinct biological context from their heterosexual counterparts, but also in a social context that may not as rigidly bound to traditional assumptions about age, gender, and power. The significant associations among participants with partners who were the same age and the risk behavior measures in this analysis have implications for HIV prevention efforts. PMID:21290255

  11. Young Girls' and Caretakers' Reports of Problem Behavior: Comprehension and Concordance across Age, Race, and Behavior

    ERIC Educational Resources Information Center

    Slocum, Lee Ann; Simpson, Sally S.; Hipwell, Alison E.; Loeber, Rolf

    2011-01-01

    The article discusses a research instrument developed and utilized by the Pittsburgh Girls Study that asked young girls (ages 7 and 8) and their caretakers to report on the girls' involvement in a variety of problem behaviors. In this article, the authors evaluate whether comprehension, prevalence, and caretaker-child concordance of problem…

  12. Intensive Behavioral Intervention for School-Aged Children with Autism: Una Breccia nel Muro (UBM)--A Comprehensive Behavioral Model

    ERIC Educational Resources Information Center

    Fava, Leonardo; Vicari, Stefano; Valeri, Giovanni; D'Elia, Lidia; Arima, Serena; Strauss, Kristin

    2012-01-01

    Although, reviews and outcome research supports empirical evidence for Early Intensive Behavior Intervention in pre-scholars, intensive behavioral service provision for school-aged children with autism spectrum disorders (ASD) are less subject to research studies. In order to provide effective behavioral interventions for school-aged children it…

  13. Practical aspects of systems hardening

    SciTech Connect

    Shepherd, W.J.

    1989-01-01

    Applications of hardening technology in a practical system require a balance between the factors governing affordability, producibility, and survivability of the finished design. Without careful consideration of the top-level system operating constraints, a design engineer may find himself with a survivable but overweight, unproductive, expensive design. This paper explores some lessons learned in applying hardening techniques to several laser communications programs and is intended as an introductory guide to novice designers faced with the task of hardening a space system.

  14. Thermal desorption behavior of helium in aged titanium tritide films

    NASA Astrophysics Data System (ADS)

    Cheng, G. J.; Shi, L. Q.; Zhou, X. S.; Liang, J. H.; Wang, W. D.; Long, X. G.; Yang, B. F.; Peng, S. M.

    2015-11-01

    The desorption behavior of helium in TiT(1.5∼1.8)-x3Hex film samples (x = 0.0022-0.22) was investigated by thermal desorption technique in vacuum condition in this paper. The thermal helium desorption spectrometry (THDS) of aging titanium tritide films prepared by electron beam evaporation revealed that, depending on the decayed 3He concentration in the samples, there are more than four states of helium existing in the films. The divided four zones in THDS based on helium states represent respectively: (1) the mobile single helium atoms with low activation energy in all aging samples resulted from the interstitial sites or dissociated from interstitial clusters, loops and dislocations, (2) helium bubbles inside the grain lattices, (3) helium bubbles in the grain boundaries and interconnected networks of dislocations in the helium concentration of 3Hegen/Ti > 0.0094, and (4) helium bubbles near or linked to the film surface by interconnected channel for later aging stage with 3Hegen/Ti > 0.18. The proportion of helium desorption in each zone was estimated, and dissociated energies of helium for different trapping states were given.

  15. Nutritional interventions protect against age-related deficits in behavior: from animals to humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aged rats show impaired performance on motor and cognitive tasks. Similar changes in behavior occur in humans with age, and the development of methods to retard or reverse these age-related neuronal and behavioral deficits could increase healthy aging and decrease health care costs. In the present s...

  16. Method and apparatus for welding precipitation hardenable materials

    DOEpatents

    Murray, Jr., Holt; Harris, Ian D.; Ratka, John O.; Spiegelberg, William D.

    1994-01-01

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined.

  17. Method and apparatus for welding precipitation hardenable materials

    DOEpatents

    Murray, H. Jr.; Harris, I.D.; Ratka, J.O.; Spiegelberg, W.D.

    1994-06-28

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined. 5 figures.

  18. Flow and fracture of particle hardened copper-titanium alloys: Interplay of slip and twinning

    NASA Astrophysics Data System (ADS)

    Radetic, Tamara

    The flow and fracture behavior of Cu-rich Cu-Ti alloys hardened by ordered, metastable, coherent betasp' precipitates (Cusb4Ti,\\ D1sb{a} superstructure) are particularly interesting because these alloys show an unusual propensity to twin profusely after small amounts of plastic flow by slip. The mechanical behavior was studied using standard tensile testing along with modern electron optical techniques including CTEM, SEM and HREM. The deformation substructure in the early stages of aging and in samples aged for longer times is characterized by the coupled motion of five dislocations of the same Burgers vector (superdislocations in the D1sb{a} structure) after small degrees of deformation. Characterization of the fine-scale structure of the mechanical twins which form in the particle hardened Cu-Ti alloys is also reported in this study. The growth of deformation twins occurs via the motion of so-called G-ledges at twin/matrix interfaces and via a coalescence of fine twins. The atomic structure of the coherent twin/matrix interfaces and associated single and multiple layer ledges are also elucidated. Incoherent interfaces at the tip of deformation twins generated by 90sp° and 30sp° twinning dislocations have been investigated. The twin/twin and slip/twin interactions have been studied and analyzed as well as the effect of grain boundaries on deformation twinning. Deformation twins appear to nucleate at dislocation pile-ups serving as a stress relaxation mechanism. Shear transfer through obstacle twins is effected by slip and twining. The dominant strengthening mechanism is concluded to be coherency strain hardening and the interplay of particle strengthening and grain size hardening is analyzed. The particle dispersion was found to influence the Hall-Petch factor but a detailed understanding of these synergetic effects was not established. The fracture mode of the underaged Cu-Ti alloys was found to be dimpled ductile tearing.

  19. Multipurpose hardened spacecraft insulation

    NASA Technical Reports Server (NTRS)

    Steimer, Carlos H.

    1990-01-01

    A Multipurpose Hardened Spacecraft Multilayer Insulation (MLI) system was developed and implemented to meet diverse survivability and performance requirements. Within the definition and confines of a MLI assembly (blanket), the design: (1) provides environmental protection from natural and induced nuclear, thermal, and electromagnetic radiation; (2) provides adequate electrostatic discharge protection for a geosynchronous satellite; (3) provides adequate shielding to meet radiated emission needs; and (4) will survive ascent differential pressure loads between enclosed volume and space. The MLI design is described which meets these requirements and design evolution and verification is discussed. The application is for MLI blankets which closeout the area between the laser crosslink subsystem (LCS) equipment and the DSP spacecraft cabin. Ancillary needs were implemented to ease installation at launch facility and to survive ascent acoustic and vibration loads. Directional venting accommodations were also incorporated to avoid contamination of LCS telescope, spacecraft sensors, and second surface mirrors (SSMs).

  20. Behavior problems at ages 6 and 11 and high school academic achievement: longitudinal latent variable modeling.

    PubMed

    Breslau, Naomi; Breslau, Joshua; Miller, Elizabeth; Raykov, Tenko

    2011-02-28

    Previous studies documented long-run effects of behavior problems at the start of school on academic achievement. However, these studies did not examine whether the observed effects of early behavior problems are explained by more proximate behavior problems, given the tendency of children's behavior problems to persist. Latent variable modeling was applied to estimate the effects of behavior problems at ages 6 and 11 on academic achievement at age 17, using data from a longitudinal study (n=823). Behavior problems at ages 6 and 11, each stage independently of the other, predicted lower math and reading test scores at age 17, controlling for intelligence quotient (IQ), birth weight, maternal characteristics, family and community environment, and taking into account behavior problems at age 17. Behavior problems at the start of school, independent of later behavior problems, exert lingering effects on achievement by impeding the acquisition of cognitive skills that are the foundation for later academic progress. PMID:20719395

  1. Behavioral activating effects of adrafinil in aged canines.

    PubMed

    Siwak, C T; Gruet, P; Woehrlé, F; Schneider, M; Muggenburg, B A; Murphey, H L; Callahan, H; Milgram, N W

    2000-06-01

    Adrafinil, a vigilance enhancing pharmaceutical, was administered to aged dogs for 14 consecutive days at doses of 10, 20, 30, or 40 mg/kg using a crossover design. The effects on spontaneous behavior in a 10-min canine open-field test were systematically recorded every fourth day, starting with day 1 of treatment. The open field tests were given 2 or 10 h following oral administration of capsules containing either adrafinil or lactose, the placebo control. Adrafinil caused an increase in locomotor activity at the three highest doses at both the 2- and 10-h intervals and during both the first (days 1 and 5) and second treatment week (days 9 and 13). Adrafinil also caused a transient increase in directed sniffing. At the highest dose level, adrafinil caused a decrease in urination frequency. The increased locomotion was generally unaccompanied by stereotypical behavior in the test session. There was some variability; a subpopulation of animals showed either no effect, or decreased locomotion. The individual differences were correlated with changes in serum levels of adrafinil 10 h following treatment. PMID:10880681

  2. Age Differences and Changes of Coping Behavior in Three Age Groups: Findings from the Georgia Centenarian Study

    ERIC Educational Resources Information Center

    Martin, Peter; Kliegel, Matthias; Rott, Christoph; Poon, Leonard W.; Johnson, Mary Ann

    2008-01-01

    With increasing age, older adults are more likely to be challenged by an increasing number of physical, functional and social losses. As a result, coping with losses becomes a central theme in very late life. This study investigated age differences and age changes in active behavioral, active cognitive and avoidance coping and related coping to…

  3. The importance of genotype-by-age interactions for the development of repeatable behavior and correlated behaviors over lifetime

    PubMed Central

    2015-01-01

    Behaviors are highly plastic and one aspect of this plasticity is behavioral changes over age. The presence of age-related plasticity in behavior opens up the possibility of between-individual variation in age-related plasticity (Individual-Age interaction, IxA) and genotype-age interaction (GxA). We outline the available approaches for quantifying GxA. We underline that knowledge of GxA for behaviors is an important step in reaching and understanding of the evolution of plasticity in behavior over lifetime. In particular, the heritability (repeatability) and/or the rank order of behavior across individuals are predicted to change across ages in presence of GxA. We draw on the theory of reaction norms to illustrate that GxA, when present, is likely to lead to developmental changes in the magnitude and possibly sign of the genetic correlation between behaviors (behavioral syndrome). We present an overview of the literature on changes in the ranking of individuals’ behavior across ages, and in the correlation between behaviors. Although all studies were carried out on the phenotypic level, they overall suggest clear scope for increased study of GxA as a process explaining age-related plasticity in behaviors. Lastly, we throughout emphasize that many of the approaches and underlying theory of GxA is applicable to the study of IxA, which is informative as it presents the upper limit of GxA, but is also a more attainable target of study in many systems. Empirical work aimed at understanding IxA and GxA in behavior is needed in order to understand whether patterns predicted by theory on plasticity indeed occur for age-related plasticity of behavior. PMID:26816518

  4. The importance of genotype-by-age interactions for the development of repeatable behavior and correlated behaviors over lifetime.

    PubMed

    Brommer, Jon E; Class, Barbara

    2015-01-01

    Behaviors are highly plastic and one aspect of this plasticity is behavioral changes over age. The presence of age-related plasticity in behavior opens up the possibility of between-individual variation in age-related plasticity (Individual-Age interaction, IxA) and genotype-age interaction (GxA). We outline the available approaches for quantifying GxA. We underline that knowledge of GxA for behaviors is an important step in reaching and understanding of the evolution of plasticity in behavior over lifetime. In particular, the heritability (repeatability) and/or the rank order of behavior across individuals are predicted to change across ages in presence of GxA. We draw on the theory of reaction norms to illustrate that GxA, when present, is likely to lead to developmental changes in the magnitude and possibly sign of the genetic correlation between behaviors (behavioral syndrome). We present an overview of the literature on changes in the ranking of individuals' behavior across ages, and in the correlation between behaviors. Although all studies were carried out on the phenotypic level, they overall suggest clear scope for increased study of GxA as a process explaining age-related plasticity in behaviors. Lastly, we throughout emphasize that many of the approaches and underlying theory of GxA is applicable to the study of IxA, which is informative as it presents the upper limit of GxA, but is also a more attainable target of study in many systems. Empirical work aimed at understanding IxA and GxA in behavior is needed in order to understand whether patterns predicted by theory on plasticity indeed occur for age-related plasticity of behavior. PMID:26816518

  5. General analytical shakedown solution for structures with kinematic hardening materials

    NASA Astrophysics Data System (ADS)

    Guo, Baofeng; Zou, Zongyuan; Jin, Miao

    2016-04-01

    The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems: a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

  6. A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary M11-xM2xB2 alloys with AlB2 type structure

    NASA Astrophysics Data System (ADS)

    Alling, B.; Högberg, H.; Armiento, R.; Rosen, J.; Hultman, L.

    2015-05-01

    Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary M11-xM2xB2 alloys comprising MiB2 (Mi = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1-xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at EF in TiB2, ZrB2, and HfB2.

  7. A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary M11–xM2xB2 alloys with AlB2 type structure

    PubMed Central

    Alling, B.; Högberg, H.; Armiento, R.; Rosen, J.; Hultman, L.

    2015-01-01

    Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary M11–xM2xB2 alloys comprising MiB2 (Mi = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1–xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at EF in TiB2, ZrB2, and HfB2. PMID:25970763

  8. Computed tomographic beam-hardening artefacts: mathematical characterization and analysis

    PubMed Central

    Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun

    2015-01-01

    This paper presents a mathematical characterization and analysis of beam-hardening artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-hardening of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-hardening factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-hardening artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis. PMID:25939628

  9. Computed tomographic beam-hardening artefacts: mathematical characterization and analysis.

    PubMed

    Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun

    2015-06-13

    This paper presents a mathematical characterization and analysis of beam-hardening artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-hardening of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-hardening factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-hardening artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis. PMID:25939628

  10. Influence of Aging Treatments on Alterations of Microstructural Features and Stress Corrosion Cracking Behavior of an Al-Zn-Mg Alloy

    NASA Astrophysics Data System (ADS)

    Rout, Prasanta Kumar; Ghosh, M. M.; Ghosh, K. S.

    2015-07-01

    7xxx series Al-Zn-Mg-(Cu) alloys have higher strength in their peak-aged (T6) states compared with other age-hardenable aluminum alloys; however, the maximum strength peak-aged state is more susceptible to stress corrosion cracking (SCC) which leads to catastrophic failure. The over-aged (T7) temper with 10-15% lower strength has higher resistance to SCC requiring oversized structural aerospace component applications. The medium-strength AA7017 Al-Zn-Mg weldable alloy without Cu is also prone to SCC under certain environmental conditions. In the present investigation, the SCC behaviors of an AA7017 Al-Zn-Mg alloys of different tempers have been assessed. Specific aging schedules have been adapted to an AA7017 alloy to produce various tempers, e.g., under-, peak-(T6), over-(T7), and highly over-aged tempers. Artificial aging behavior of the AA7017 alloy has been characterized by hardness, electrical conductivity measurements, x-ray diffraction, differential scanning calorimetry, and electrochemical studies. Slow strain rate test technique was used to assess the SCC behaviors of the AA7017 alloys of under-, T6, T7, and highly over-aged tempers in 3.5 wt.% NaCl solution at free corrosion potential (FCP) and at applied anodic potential, as well. Results revealed that the AA7017 alloy tempers are not susceptible to SCC in 3.5 wt.% NaCl solution at FCP, but severely damaging to SCC at applied anodic potentials. Microstructural features, showing a non-recrystallized grain structure and the presence of discrete, widely spaced, not-interconnected η precipitates at the grain boundaries, are the contributive factors by virtue of which the alloy tempers at FCP did not exhibit SCC. However, the applied anodic potential resulted in rapid metal dissolution from the grain boundary region and led to SCC. The local anodic dissolution (LAD) is believed to be the associated SCC mechanism.

  11. Age and HIV Risk and Protective Behaviors among African American Women

    ERIC Educational Resources Information Center

    Corneille, Maya A.; Zyzniewski, Linda E.; Belgrave, Faye Z.

    2008-01-01

    Though HIV prevention efforts have focused on young adult women, women of all ages may engage in HIV risk behaviors and experience barriers to condom use. This article examines the effect of age on sexual risk and protective attitudes and behaviors among African American women. Unmarried heterosexual African American women between the ages of 18…

  12. Stage IV work hardening in cubic metals

    SciTech Connect

    Rollett, A.D.; Kocks, U.F.; Doherty, R.D.

    1986-01-01

    The work hardening of fcc metals at large strains is discussed with reference to the linear stress-strain behavior often observed at large strains and known as Stage IV. The experimental evidence shows that Stage IV is a work hardening phenomenon that is found quite generally, even in pure fcc metals subjected to homogeneous deformation. A simple model for Stage IV in pure metals is presented, based on the accumulation of dislocation debris. Experiments are described for large strain torsion tests on four aluminum alloys. The level and extent of Stage IV scaled with the saturation stress that would represent the end of Stage III in the absence of a Stage IV. Reversing the torsion after large prestrains produced transient reductions in the work hardening. The strain rate sensitivity was also measured before and during the transient and found not to vary significantly. The microstructure observed at large strains in an Mg alloy suggest that Stage IV can occur in the absence of microband formation. Previous proposals for the cause of Stage IV are reviewed and found to be not supported by recent experimental data.

  13. Bicycle safety knowledge and behavior in school age children.

    PubMed

    Kimmel, S R; Nagel, R W

    1990-06-01

    The purpose of this study was to examine school age children's knowledge of bicycling rules of the road and their bicycling behaviors. A one-page questionnaire was administered in the classroom to 276 of 300 children in grades 4 through 8 of an upper middle class suburban school district. The children were questioned regarding their knowledge of three basic bicycling rules of the road, prior bicycle safety instruction, use of bicycle helmets, and the occurrence and severity of previous bicycle accidents. Students who reported receiving previous bicycle safety instruction were more knowledgeable than those receiving no instruction regarding rule 2, always stop at a stop sign or red light (90% compared with 74%), and rule 3, always stop and look when approaching a street from a driveway or alley (74% compared with 60%). Students who did not know rule 3 were more likely to have had a recent bicycle accident in which their bicycle was damaged (21% compared with 8%) and to have ever gone to the hospital or a physician because of injuries sustained in a bicycle accident (19% compared with 9%). Children who lacked knowledge of basic bicycling rules were more likely to have had a significant bicycling accident. Bicycle safety instruction increases children's knowledge of these rules and should be promoted by physicians caring for children. PMID:2345336

  14. System-Level Radiation Hardening

    NASA Technical Reports Server (NTRS)

    Ladbury, Ray

    2014-01-01

    Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.

  15. Phase Transformation and Aging Behavior of Al0.5CoCrFeNiSi0.2 High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Wu, G. F.; Dai, P. Q.

    2015-05-01

    An Al0.5CoCrFeNiSi0.2 high-entropy alloy was prepared by vacuum arc melting. The alloy was aged from 700 to 1100 °C. The effects of aging on the phase transformation and mechanical performances were explored. The as-cast alloy showed a dendritic (DR) microstructure. The DR region was an Fe,Cr-rich FCC phase, while the interdendritic (ID) region was a spinodal structure composed of Fe,Cr-rich BCC (A2) and Ni,Al-rich BCC (B2) phases. At aging temperatures between 700 and 900 °C, the Fe,Cr-rich BCC (A2) phase in the ID region transformed into σ and Fe,Cr-rich FCC phases. Meanwhile, some Ni,Al-rich FCC phase particles precipitated from the DR region. During aging at 1100 °C, the DR microstructure disappeared, and a microstructure composed of Fe,Cr-rich FCC and Ni,Al-rich BCC (B2) phases both possessing a lamellar shape was developed. The alloy exhibited evident hardening and lower tensile strain when the aging temperature was lower than 1000 °C, which was mainly attributed to the generation of the σ phase in the ID region. However, a contrasting behavior was observed when the aging temperature was higher than 1000 °C, which was attributed to the redissolution of the σ phase and the microstructure coarsening.

  16. Relating Age Change and Behavior to Job Requirements.

    ERIC Educational Resources Information Center

    Schaie, K. Warner

    The Age Discrimination in Employment Act has been amended to outlaw mandatory retirement at any age. However, the act permits employers to impose a specific retirement age if there is a bona fide occupational qualification (BFOQ) which cannot be met by all or most individuals. Imposition of BFOQ mandatory retirement ages by employers has led to…

  17. Reduced Electrodermal Fear Conditioning from Ages 3 to 8 Years Is Associated with Aggressive Behavior at Age 8 Years

    PubMed Central

    Gao, Yu; Raine, Adrian; Venables, Peter H.; Dawson, Michael E.; Mednick, Sarnoff A.

    2010-01-01

    Background Poor fear conditioning characterizes adult psychopathy and criminality, but it is not known whether it is related to aggressive/antisocial behavior in early childhood. Methods Using a differential, partial reinforcement conditioning paradigm, electrodermal activity was recorded from 200 male and female children at ages 3, 4, 5, 6, and 8 years. Antisocial/aggressive and hyperactive-inattentive measures were collected at age 8, while social adversity was assessed at age 3. Results Poor electrodermal fear conditioning from ages 3 to 8 years was associated with aggressive behavior at age 8 in both males and females. Conclusions Results indicate that the relationship between poor fear conditioning and aggression occurs early in childhood. Enhanced electrodermal fear conditioning may protect children against future aggressive/violent behavior. Abnormal amygdala functioning, as indirectly assessed by fear conditioning, may be one of the factors influencing the development of childhood aggression. PMID:19788551

  18. Solute hardening and softening effects in B2 nickel aluminides

    SciTech Connect

    Pike, L.M.; Liu, C.T.; Anderson, I.M.; Chang, Y.A.

    1998-11-01

    The effect of substitutional solute additions including Fe, Mn, and Pd on the hardness of B2-ordered NiAl alloys was investigated. The solid solution hardening behavior of intermetallics is more complex than that of typical metallic solid solutions because of complications arising from the site preference of the solute as well as the effects of the solute on the concentrations of other point defects, e.g., vacancies and anti-site defects. For this reason, care was taken to experimentally establish solute site preferences and point defect concentrations in the NiAl alloys before analyzing the hardness data. By taking these factors into account it was possible to rationalize the observed unusual hardening effects. Three distinct categories of solid solution hardening behavior were encountered. The first was hardening by the solute addition itself. This was observed in the case of Pd additions to Al-poor NiAl. However, when fe or Mn is added to Al-poor NiAl a second category is observed; these elements are seen to soften the material. The third category of behavior is observed when Fe is added to NiAl with a constant Al concentration of 50 at. %. In this case it is vacancies, rather than solute atoms, which harden the material.

  19. Trajectories of Externalizing Behavior from Age 2 to Age 9: Relations with Gender, Temperament, Ethnicity, Parenting, and Rater

    ERIC Educational Resources Information Center

    Miner, Jennifer L.; Clarke-Stewart, K. Alison

    2008-01-01

    Trajectories of children's externalizing behavior were examined using multilevel growth curve modeling of data from the NICHD Study of Early Child Care and Youth Development. According to ratings by both mothers and caregivers/teachers when children were 2, 3, 4, 7, and 9 years old, externalizing behavior declined with age. However, mothers rated…

  20. Explosive Surface Hardening of Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kovacs-Coskun, T.

    2016-04-01

    In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea mean indirect hardening setup. Austenitic stainless steels have high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

  1. Anisotropic hardening model based on non-associated flow rule and combined nonlinear kinematic hardening for sheet materials

    NASA Astrophysics Data System (ADS)

    Taherizadeh, Aboozar; Green, Daniel E.; Yoon, Jeong W.

    2013-12-01

    A material model for more effective analysis of plastic deformation of sheet materials is presented in this paper. The model is capable of considering the following aspects of plastic deformation behavior of sheet materials: the anisotropy in yielding stresses in different directions by using a quadratic yield function (based on Hill's 1948 model and stress ratios), the anisotropy in work hardening by introducing non-constant flow stress hardening in different directions, the anisotropy in plastic strains in different directions by using a quadratic plastic potential function and non-associated flow rule (based on Hill's 1948 model and plastic strain ratios, r-values), and finally some of the cyclic hardening phenomena such as Bauschinger's effect and transient behavior for reverse loading by using a coupled nonlinear kinematic hardening (so-called Armstrong-Frederick-Chaboche model). Basic fundamentals of the plasticity of the model are presented in a general framework. Then, the model adjustment procedure is derived for the plasticity formulations. Also, a generic numerical stress integration procedure is developed based on backward-Euler method (so-called multi-stage return mapping algorithm). Different aspects of the model are verified for DP600 steel sheet. Results show that the new model is able to predict the sheet material behavior in both anisotropic hardening and cyclic hardening regimes more accurately. By featuring the above-mentioned facts in the presented constitutive model, it is expected that more accurate results can be obtained by implementing this model in computational simulations of sheet material forming processes. For instance, more precise results of springback prediction of the parts formed from highly anisotropic hardened materials or that of determining the forming limit diagrams is highly expected by using the developed material model.

  2. Effect of moisture on the aging behavior of asphalt binder

    NASA Astrophysics Data System (ADS)

    Ma, Tao; Huang, Xiao-Ming; Mahmoud, Enad; Garibaldy, Emil

    2011-08-01

    The moisture aging effect and mechanism of asphalt binder during the in-service life of pavement were investigated by laboratory simulating tests. Pressure aging vessel (PAV) test simulating the long-term aging of binder during the in-service life of pavement was modified to capture the long-term moisture aging effect of binder. Penetration grade tests including penetration test, soften point test, and ductility test as well as Superpave™ performance grade tests including viscosity test, dynamic shear rheometer test, and bending beam rheometer test were conducted to fully evaluate the moisture aging effect of binder. Fourier transform infrared spectroscopy test and Gel-permeation chromatography test were applied to provide a fundamental understanding of the moisture aging mechanism of binder. The results indicate that moisture condition can accelerate the aging of asphalt binder and shorten the service life of asphalt binder. The modified PAV test with moisture condition can well characterize the moisture aging properties of asphalt binder.

  3. Maladaptive Behaviors Related to Adaptive Decline in Aging Adults with Mental Retardation.

    ERIC Educational Resources Information Center

    Urv, Tiina K.; Zigman, Warren B.; Silverman, Wayne

    2003-01-01

    Changes in patterns of maladaptive behavior related to age-associated adaptive declines were investigated in 529 adults with mental retardation (ages 30 to 84), 202 with Down syndrome. Certain maladaptive behaviors were related to the onset of adaptive declines, (e.g., lack of boundaries). Findings suggest similarities in the course of…

  4. Health-Risk Behaviors among Persons Aged 12-21 Years: United States, 1992.

    ERIC Educational Resources Information Center

    Center for Disease Control (DHHS/PHS), Atlanta, GA.

    Noting that health-risk behaviors among youth may result in immediate health problems or extend into adulthood and increase risk for chronic diseases, this report examines the prevalence of health-risk behaviors among a nationally representative sample of persons aged 12 to 21 years and presents age group comparisons of the most important…

  5. Rural Adolescent Health Risk Behaviors: Age, Gender, and Ethnic Differences.

    ERIC Educational Resources Information Center

    Salzman, Stephanie A.; Girvan, James T.

    A survey of health risk behaviors was administered to a representative sample of 7,776 Idaho students in grades 8-12. Respondents were 86% White, 6% Hispanic, 4% American Indian, 3% Asian, and 2% Black. These rural adolescents reported that they had engaged in some health risk behaviors at rates comparable to those of other U.S. adolescents: 57%…

  6. Dynamic bake hardening of interstitial-free steels

    SciTech Connect

    Dehghani, K.; Jonas, J.J.

    2000-05-01

    Two types of dynamic strain aging (DSA) strengthening methods were investigated to determine their potentials for industrial use. They are referred to here as dynamic-static bake hardening (DSBH) and dynamic bake hardening (DBH). For this purpose, a 0.06 pct Ti interstitial-free (IF) steel was reheated to 900 C and cooled at 12 C/s to room temperature. It was then dynamically bake hardened in the temperature range 100 C to 250 C to strains of 2 to 8 pct at a strain rate of 10{sup {minus}3} s{sup {minus}1}. The tensile properties were determined before and after these treatments. It was found that the occurrence of DSA during dynamic baking led to significant increases in work-hardening rate as well as in the final strength. The results indicate that, for a given solute carbon level, the dynamically and then statically aged samples have higher strengths than those that are bake hardened in the conventional way.

  7. Age and sex differences in behaviors mediated by the ventromedial hypothalamus.

    PubMed

    Nisbett, R E; Braver, A; Jusela, G; Kezur, D

    1975-02-01

    Age and sex differences in behaviors mediated by the ventromedial hypothalamus (VMH) were examined in the rat. Circadian rhythm, emotionality, and taste responsiveness (except for responsiveness to quinine adulteration) were found to shift, in one or both sexes, toward a pattern suggesting decreased VMH functioning with increasing age. A post hoc analysis of the configuration of positive and negative results suggests that, for those behaviors known to show both immediate and sustained effects of VMH lesion, male rats show a marked trend toward the lesioned pattern of behavior with increasing age, whereas females show weaker or nonexistent age trends in the same behaviors. For those behaviors that have been shown to change only during the static, obese phase, or for which data re controversial as to whether changes take place as a result of the VMH lesion at all, this age and sex pattern does not emerge. PMID:1150946

  8. Beneficial effects of berryfruit polyphenols on neuronal behavioral aging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is becoming increasingly clear that although there is a great deal of research being devoted to elucidating the molecular mechanisms involved in aging, practical information on how to forestall or reverse the deleterious effects of aging may be years away. Therefore, it may be beneficial to dete...

  9. An Evaluation of the Aberrant Behavior Checklist for Children under Age 5

    ERIC Educational Resources Information Center

    Schmidt, Jonathan D.; Huete, John M.; Fodstad, Jill C.; Chin, Michelle D.; Kurtz, Patricia F.

    2013-01-01

    Severe problem behaviors such as self-injury and aggression are frequently observed in young children under age 5 with intellectual and developmental disabilities (IDD). Although early identification of problem behavior is critical to effective intervention, there are few standardized measures available that identify severe problem behavior in…

  10. Total dose performance of radiation hardened voltage regulators and references

    NASA Technical Reports Server (NTRS)

    McClure, S.; Gorelick, J.; Pease, R.; Rax, B.; Ladbury, R.

    2001-01-01

    Total dose test of commercially available radiation hardened bipolar voltage regulators and references show reduced sensitivity to dose rate and varying sensitivity to bias under pressure. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed.

  11. Production and Precipitation Hardening of Beta-Type Ti-35Nb-10Cu Alloy Foam for Implant Applications

    NASA Astrophysics Data System (ADS)

    Mutlu, Ilven; Yeniyol, Sinem; Oktay, Enver

    2016-04-01

    In this study, beta-type Ti-35Nb-10Cu alloy foams were produced by powder metallurgy method for dental implant applications. 35% Nb was added to stabilize the beta-Ti phase with low Young's modulus. Cu addition enhanced sinterability and gave precipitation hardening capacity to the alloy. Sintered specimens were precipitation hardened in order to enhance the mechanical properties. Electrochemical corrosion behavior of the specimens was examined by electrochemical impedance spectroscopy in artificial saliva. Electrochemical impedance spectroscopy results indicated that the oxide film on the surface of foam is a bi-layer structure consisting of outer porous layer and inner barrier layer. Impedance values of barrier layer were higher than porous layer. Corrosion resistance of specimens decreased at high fluoride concentrations and at low pH of artificial saliva. Corrosion resistance of alloys was slightly decreased with aging. Mechanical properties, microstructure, and surface roughness of the specimens were also examined.

  12. Behavioral Group Work in a Home for the Aged

    ERIC Educational Resources Information Center

    Linsk, N.; And Others

    1975-01-01

    Elderly people in institutions frequently become isolated and noncommunicative. By using behavioral measurements of group workers and group members, the authors have formulated ways of treatment that encourage members to participate more actively. (Author)

  13. Age Differences in Coping, Behavioral Dysfunction and Depression Following Colostomy Surgery.

    ERIC Educational Resources Information Center

    Keyes, Kathryn; And Others

    1987-01-01

    Examined the responses of a group of middle-aged and older adults (N=34) to colostomy surgery. Analyzed the relationship between the method and focus of coping and age, sickness-related dysfunction, and depression. Found that neither a lower level of active behavioral coping nor age itself was correlated with depression or dysfunction. (Author/ABB)

  14. Strain hardening during mechanical twining and dislocation channeling in irradiated 316 stainless steels

    SciTech Connect

    Byun, Thak Sang; Hashimoto, Naoyuki

    2007-01-01

    Localized deformation mechanisms and strain-hardening behaviors in irradiated 316 and 316LN stainless steels were investigated, and a theoretical model was proposed to explain the linear strain-hardening behavior during the localized deformation. After low temperature irradiation to significant doses the deformation microstructure changed from dislocation tangles to channels or to mechanical twins. It was also observed that irradiation hardening straightened gliding dislocations and increased the tendency for forming pileups. Regardless of these microstructural changes, the strain-hardening behavior was relatively insensitive to the irradiation. This dose-independent strain-hardening rate resulted in dose independence of the true stress parameters such as the plastic instability stress and true fracture stress. In the proposed model, the long-range back stress was formulated as a function of the number of pileup dislocations per slip band and the number of slip bands in a grain. The calculation results confirmed the experimental observation that strain-hardening rate was insensitive to the change in deformation mechanism because the long-range back stress hardening became as high as the hardening by tangled dislocations.

  15. Statistical thermodynamics of strain hardening in polycrystalline solids

    SciTech Connect

    Langer, James S.

    2015-09-18

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman. The paper then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  16. Statistical thermodynamics of strain hardening in polycrystalline solids

    SciTech Connect

    Langer, James S.

    2015-01-01

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman. The paper then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  17. Statistical thermodynamics of strain hardening in polycrystalline solids

    NASA Astrophysics Data System (ADS)

    Langer, J. S.

    2015-09-01

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman [Acta Mat. 58, 3718 (2010), 10.1016/j.actamat.2010.03.009]. It then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  18. Grape powder treatment prevents anxiety-like behavior in a rat model of aging.

    PubMed

    Patki, Gaurav; Ali, Quaisar; Pokkunuri, Indira; Asghar, Mohammad; Salim, Samina

    2015-06-01

    Earlier, we have reported that grape powder (GP) treatment prevented pharmacologic and psychological stress-induced anxiety-like behavior and memory impairment in rats. Protective effects of GP were attributed to its antioxidant effects. In this study, we tested the hypothesis that age-associated behavioral and cognitive deficits such as anxiety and memory impairment will be ameliorated with GP treatment. Using a National Institute of Aging recommended rodent model of aging, we examined a potentially protective role of antioxidant-rich GP in age-associated anxiety-like behavior and memory impairment. Male Fischer 344 rats were randomly assigned into 4 groups: young rats (3 months old) provided with tap water or with 15 g/L GP dissolved in tap water for 3 weeks, aged rats (21 months old) provided with tap water or with GP-treated tap water for 3 weeks (AG-GP). Anxiety-like behavior was significantly greater in aged rats compared with young rats, GP-treated young rats, or aged control rats (P < .05). Also, GP treatment prevented age-induced anxiety-like behavior in AG-GP rats (P < .05). Neither short-term nor long-term age-associated memory deficits improved with GP treatment in AG-GP rats. Furthermore, aged rats showed increased level of physiological stress (corticosterone) and increased oxidative stress in the plasma (8-isoprostane) as well as in selected brain areas (protein carbonylation). Grape powder treatment prevented age-induced increase in corticosterone levels and plasma 8-isoprostane levels in aged rats (P < .05), whereas protein carbonylation was recovered in the amygdala region only (P < .05). Grape powder by regulating oxidative stress ameliorates age-induced anxiety-like behavior in rats, whereas age-associated memory deficits seem unaffected with GP treatment. PMID:26022140

  19. Precipitation Behavior During Aging in α Phase Titanium Supersaturated with Cu

    NASA Astrophysics Data System (ADS)

    Mitsuhara, Masatoshi; Masuda, Tomoya; Nishida, Minoru; Kunieda, Tomonori; Fujii, Hideki

    2016-04-01

    Age hardening of Ti-2.3 mass pct Cu (Ti-2.3Cu) at 673 K to 873 K (400 °C to 600 °C) after solution treatment at 1063 K (790 °C) was observed. The relationship between precipitates formed during aging and changes in hardness was investigated. During aging at 673 K (400 °C), the hardness increased rapidly up to 200 hours, and subsequently increased more slowly up to 1000 hours. At 873 K (600 °C), the hardness began to decrease immediately. Transmission electron microscopy showed that fine disk-shaped precipitates of 20 to 40 nm in diameter grew in the α phase. It is concluded that these precipitates interacted with dislocations and increased the hardness. At 873 K (600 °C), precipitates of 1 µm in length and Ti2Cu particles of 200 nm in length were observed. The decrease in hardness may have resulted from the precipitate formation decreasing the concentration of Cu in the α phase. Bright/dark contrast of the three atomic layers and small atomic shift of the hcp structure were observed in the atomic resolution imaging of the precipitates. This suggests that the precipitates are not just Cu-enriched zones and have structures with similar periodicity to the Ti2Cu phase, which is thermally stable at those aging temperatures.

  20. Effects of age, dietary, and behavioral enrichment on brain mitochondria in a canine model of human aging.

    PubMed

    Head, E; Nukala, V N; Fenoglio, K A; Muggenburg, B A; Cotman, C W; Sullivan, P G

    2009-11-01

    Dogs develop cognitive decline and a progressive accumulation of oxidative damage. In a previous longitudinal study, we demonstrated that aged dogs treated with either an antioxidant diet or with behavioral enrichment show cognitive improvement. The antioxidant diet included cellular antioxidants (vitamins E and C, fruits and vegetables) and mitochondrial cofactors (lipoic acid and carnitine). Behavioral enrichment consisted of physical exercise, social enrichment, and cognitive training. We hypothesized that the antioxidant treatment improved neuronal function through increased mitochondrial function. Thus, we measured reactive oxygen species (ROS) production and bioenergetics in mitochondria isolated from young, aged, and treated aged animals. Aged canine brain mitochondria show significant increases in ROS production and a reduction in NADH-linked respiration. Mitochondrial function (ROS and NADH-linked respiration) was improved selectively in aged dogs treated with an antioxidant diet. In contrast, behavioral enrichment had no effect on any mitochondrial parameters. These results suggest that an antioxidant diet improves cognition by maintaining mitochondrial homeostasis, which may be an independent molecular pathway not engaged by behavioral enrichment. PMID:19703441

  1. Fruits, Nuts, and Brain Aging: Nutritional Interventions Targeting Age-Related Neuronal and Behavioral Deficits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    By the year 2050, 30% of the total population of the US will be over 65 years of age. As the aged population expands, the economic burden of care and treatment of those with age-related health disorders also increases, necessitating the immediate implementation of therapeutics to prevent or even rev...

  2. Undergraduate Students' Perceptions and Behaviors Related to the Aged and to Aging Processes

    ERIC Educational Resources Information Center

    Van Dussen, Daniel J.; Weaver, Robert R.

    2009-01-01

    Aging education is relatively new to the university, and our understanding of the perspectives students bring to aging populations is correspondingly limited. This investigation surveys 546 students at a midsized, Midwestern university to explore students' views toward elders, toward serving elders, and toward the relevance of aging education for…

  3. Life on the Hardened Border

    ERIC Educational Resources Information Center

    Miller, Bruce Granville

    2012-01-01

    The many Coast Salish groups distributed on both sides of the United States-Canada border on the Pacific coast today face significant obstacles to cross the international border, and in some cases are denied passage or intimidated into not attempting to cross. The current situation regarding travel by Aboriginal people reflects the "hardening" of…

  4. Onycholysis induced by nail hardener.

    PubMed

    Helsing, Per; Austad, Joar; Talberg, Hans Jørgen

    2007-10-01

    Nail hardeners appeared in the market during the 1960s. They were basically solutions of formaldehyde. The first adverse effects were published in 1966 (1). Reactions were onycholysis, chromonychia, subungual haemorrhage, and hyperkeratosis. Onycholysis may be non-inflammatory or inflammatory, and is accompanied by throbbing pain. Inflammatory reactions are followed by paronychia and occasional dermatitis on the digital pulpa. PMID:17868227

  5. Behavioral deficits during early stages of aging in Caenorhabditis elegans result from locomotory deficits possibly linked to muscle frailty.

    PubMed Central

    Glenn, Charles F.; Chow, David K.; Gami, Minaxi S.; Iser, Wendy B.; Hanselman, Keaton B.; Wolkow, Catherine A.; David, Lawrence; Goldberg, Ilya G.; Cooke, Carol A.

    2005-01-01

    Many behavioral responses require the coordination of sensory inputs with motor outputs. Aging is associated with progressive declines in both motor function and muscle structure. However, the consequences of age-related motor deficits upon behavior have not been clearly defined. Here, we examined the effects of aging on behavior in the nematode, Caenorhabditis elegans. As animals aged, mild locomotory deficits appeared that were sufficient to impair behavioral responses to sensory cues. In contrast, sensory ability appeared well-maintained during aging. Age-related behavioral declines were delayed in animals with mutations in the daf-2/insulin-like pathway governing longevity. A decline in muscle tissue integrity was correlated with the onset of age-related behavioral deficits, although significant muscle deterioration did not. Treatment with a muscarinic agonist significantly improved locomotory behavior in aged animals, indicating that improved neuromuscular signaling may be one strategy for reducing the severity of age-related behavioral impairments. PMID:15699524

  6. Behavioral deficits during early stages of aging in Caenorhabditis elegans result from locomotory deficits possibly linked to muscle frailty.

    PubMed

    Glenn, Charles F; Chow, David K; David, Lawrence; Cooke, Carol A; Gami, Minaxi S; Iser, Wendy B; Hanselman, Keaton B; Goldberg, Ilya G; Wolkow, Catherine A

    2004-12-01

    Many behavioral responses require the coordination of sensory inputs with motor outputs. Aging is associated with progressive declines in both motor function and muscle structure. However, the consequences of age-related motor deficits on behavior have not been clearly defined. Here, we examined the effects of aging on behavior in the nematode, Caenorhabditis elegans. As animals aged, mild locomotory deficits appeared that were sufficient to impair behavioral responses to sensory cues. In contrast, sensory ability appeared well maintained during aging. Age-related behavioral declines were delayed in animals with mutations in the daf-2/insulin-like pathway governing longevity. A decline in muscle tissue integrity was correlated with the onset of age-related behavioral deficits, although significant muscle deterioration was not. Treatment with a muscarinic agonist significantly improved locomotory behavior in aged animals, indicating that improved neuromuscular signaling may be one strategy for reducing the severity of age-related behavioral impairments. PMID:15699524

  7. Behavior Correlates of Rorschach Response in School Age Children.

    ERIC Educational Resources Information Center

    Martin, Frances G.

    Teachers in a private special education school for students with learning and/or adjustment difficulties completed Bristol Social Adjustment Guides (BSAGs), an observation scale for identifying maladaptive classroom behaviors, for 157 students (7-21 years old). Rorschachs were administered to the same group of students. Data from each test were…

  8. Age Differences in the Impact of Employment on Antisocial Behavior

    ERIC Educational Resources Information Center

    Monahan, Kathryn C.; Steinberg, Laurence; Cauffman, Elizabeth

    2013-01-01

    While research suggests that working more than 20 hr weekly is associated with greater antisocial behavior among middle- and upper-class youth, some have argued that employment benefits at-risk youth and leads to desistance from crime among youthful offenders. This study investigates the relation between hours worked, school attendance, and…

  9. Reduced Electrodermal Fear Conditioning from Ages 3 to 8 Years Is Associated with Aggressive Behavior at Age 8 Years

    ERIC Educational Resources Information Center

    Gao, Yu; Raine, Adrian; Venables, Peter H.; Dawson, Michael E.; Mednick, Sarnoff A.

    2010-01-01

    Background: Poor fear conditioning characterizes adult psychopathy and criminality, but it is not known whether it is related to aggressive/antisocial behavior in early childhood. Methods: Using a differential, partial reinforcement conditioning paradigm, electrodermal activity was recorded from 200 male and female children at ages 3, 4, 5, 6, and…

  10. Grape juice, berries and walnuts affect brain aging and behavior

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Numerous studies have indicated that individuals consuming a diet containing high amounts of fruits and vegetables exhibit fewer age-related diseases such as Alzheimer Disease (AD). A recent report has indicated that individuals who consumed a diet containing 2.5 servings of fruit and vegetables/day...

  11. Sex Differences in the Play Behavior of Three Age Groups.

    ERIC Educational Resources Information Center

    Clance, Pauline Rose; And Others

    Erik Erikson concluded that differences in the play constructions of young children are largely determined by psychosexual differences in the subjects and not by cultural influence. He suggested that additional observation of younger and older subjects could determine whether the differences were true for all ages or whether they were restricted…

  12. An Attachment Model of Sibling Helping Behavior in Old Age.

    ERIC Educational Resources Information Center

    Cicirelli, Victor G.

    Sibling relationships are not only maintained throughout life in most cases, but assume considerable importance in old age. Siblings provide psychological support for each other as well as more tangible forms of helping and caregiving. In order to investigate variables leading to sibling help in the area of psychological support, a path model…

  13. The Age of Initiation of Drug Use and Sexual Behavior May Influence Subsequent HIV Risk Behavior: A Systematic Review

    PubMed Central

    Potrepka, Jessica; Copenhaver, Michael

    2013-01-01

    Researchers examining injection drug users (IDUs) in drug treatment have been trying for decades to determine the optimal way to intervene to prevent the transmission and spread of human immunodeficiency virus (HIV) in this population. Although efficacious HIV risk reduction interventions are widely available, questions remain about what specific factors are most related to HIV risk behavior and defined as unprotected sexual activity and/or high risk drug use. This review involved an evaluation of the research literature in order to better understand the association between drug use and sexual behavior debut on HIV risk behavior. Findings suggest that drug use debut and sexual behavior debut may be related to subsequent HIV risk behavior. Evidence to date implies that intervening at an earlier age to assist youth to avoid or delay these high risk behaviors may be an additional means of reducing subsequent HIV risk. PMID:24381791

  14. Prenatal and Early Childhood Bisphenol A Concentrations and Behavior in School-Aged Children

    PubMed Central

    Harley, Kim G.; Gunier, Robert B.; Kogut, Katherine; Johnson, Caroline; Bradman, Asa; Calafat, Antonia M.; Eskenazi, Brenda

    2013-01-01

    Introduction Early life exposure to bisphenol A (BPA), an endocrine disrupting chemical used in some food and beverage containers, receipts, and dental sealants, has been associated with anxiety and hyperactivity in animal studies. A few human studies also show prenatal and childhood BPA exposure to be associated with behavior problems in children. Methods We measured BPA in urine from mothers during pregnancy and children at 5 years of age (N = 292). Child behavior was assessed by mother and teacher report at age 7 years and direct assessment at age 9 years. Results Prenatal urinary BPA concentrations were associated with increased internalizing problems in boys, including anxiety and depression, at age 7. No associations were seen with prenatal BPA concentrations and behaviors in girls. Childhood urinary BPA concentrations were associated with increased externalizing behaviors, including conduct problems, in girls at age 7 and increased internalizing behaviors and inattention and hyperactivity behaviors in boys and girls at age 7. Conclusions This study adds to the existing literature showing associations of early life BPA exposure with behavior problems, including anxiety, depression, and hyperactivity in children. Additional information about timing of exposure and sex differences in effect is still needed. PMID:23870093

  15. Aging and Autophagic Function Influences the Progressive Decline of Adult Drosophila Behaviors.

    PubMed

    Ratliff, Eric P; Mauntz, Ruth E; Kotzebue, Roxanne W; Gonzalez, Arysa; Achal, Madhulika; Barekat, Ayeh; Finley, Kaelyn A; Sparhawk, Jonathan M; Robinson, James E; Herr, Deron R; Harris, Greg L; Joiner, William J; Finley, Kim D

    2015-01-01

    Multiple neurological disorders are characterized by the abnormal accumulation of protein aggregates and the progressive impairment of complex behaviors. Our Drosophila studies demonstrate that middle-aged wild-type flies (WT, ~4-weeks) exhibit a marked accumulation of neural aggregates that is commensurate with the decline of the autophagy pathway. However, enhancing autophagy via neuronal over-expression of Atg8a (Atg8a-OE) reduces the age-dependent accumulation of aggregates. Here we assess basal locomotor activity profiles for single- and group-housed male and female WT flies and observed that only modest behavioral changes occurred by 4-weeks of age, with the noted exception of group-housed male flies. Male flies in same-sex social groups exhibit a progressive increase in nighttime activity. Infrared videos show aged group-housed males (4-weeks) are engaged in extensive bouts of courtship during periods of darkness, which is partly repressed during lighted conditions. Together, these nighttime courtship behaviors were nearly absent in young WT flies and aged Atg8a-OE flies. Previous studies have indicated a regulatory role for olfaction in male courtship partner choice. Coincidently, the mRNA expression profiles of several olfactory genes decline with age in WT flies; however, they are maintained in age-matched Atg8a-OE flies. Together, these results suggest that middle-aged male flies develop impairments in olfaction, which could contribute to the dysregulation of courtship behaviors during dark time periods. Combined, our results demonstrate that as Drosophila age, they develop early behavior defects that are coordinate with protein aggregate accumulation in the nervous system. In addition, the nighttime activity behavior is preserved when neuronal autophagy is maintained (Atg8a-OE flies). Thus, environmental or genetic factors that modify autophagic capacity could have a positive impact on neuronal aging and complex behaviors. PMID:26182057

  16. Aging and Autophagic Function Influences the Progressive Decline of Adult Drosophila Behaviors

    PubMed Central

    Kotzebue, Roxanne W.; Gonzalez, Arysa; Achal, Madhulika; Barekat, Ayeh; Finley, Kaelyn A.; Sparhawk, Jonathan M.; Robinson, James E.; Herr, Deron R.; Harris, Greg L.; Joiner, William J.; Finley, Kim D.

    2015-01-01

    Multiple neurological disorders are characterized by the abnormal accumulation of protein aggregates and the progressive impairment of complex behaviors. Our Drosophila studies demonstrate that middle-aged wild-type flies (WT, ~4-weeks) exhibit a marked accumulation of neural aggregates that is commensurate with the decline of the autophagy pathway. However, enhancing autophagy via neuronal over-expression of Atg8a (Atg8a-OE) reduces the age-dependent accumulation of aggregates. Here we assess basal locomotor activity profiles for single- and group-housed male and female WT flies and observed that only modest behavioral changes occurred by 4-weeks of age, with the noted exception of group-housed male flies. Male flies in same-sex social groups exhibit a progressive increase in nighttime activity. Infrared videos show aged group-housed males (4-weeks) are engaged in extensive bouts of courtship during periods of darkness, which is partly repressed during lighted conditions. Together, these nighttime courtship behaviors were nearly absent in young WT flies and aged Atg8a-OE flies. Previous studies have indicated a regulatory role for olfaction in male courtship partner choice. Coincidently, the mRNA expression profiles of several olfactory genes decline with age in WT flies; however, they are maintained in age-matched Atg8a-OE flies. Together, these results suggest that middle-aged male flies develop impairments in olfaction, which could contribute to the dysregulation of courtship behaviors during dark time periods. Combined, our results demonstrate that as Drosophila age, they develop early behavior defects that are coordinate with protein aggregate accumulation in the nervous system. In addition, the nighttime activity behavior is preserved when neuronal autophagy is maintained (Atg8a-OE flies). Thus, environmental or genetic factors that modify autophagic capacity could have a positive impact on neuronal aging and complex behaviors. PMID:26182057

  17. Effects of moderate prenatal ethanol exposure and age on social behavior, spatial response perseveration errors and motor behavior.

    PubMed

    Hamilton, Derek A; Barto, Daniel; Rodriguez, Carlos I; Magcalas, Christy M; Fink, Brandi C; Rice, James P; Bird, Clark W; Davies, Suzy; Savage, Daniel D

    2014-08-01

    Persistent deficits in social behavior are among the major negative consequences associated with exposure to ethanol during prenatal development. Prior work from our laboratory has linked deficits in social behavior following moderate prenatal alcohol exposure (PAE) in the rat to functional alterations in the ventrolateral frontal cortex [21]. In addition to social behaviors, the regions comprising the ventrolateral frontal cortex are critical for diverse processes ranging from orofacial motor movements to flexible alteration of behavior in the face of changing consequences. The broader behavioral implications of altered ventrolateral frontal cortex function following moderate PAE have, however, not been examined. In the present study we evaluated the consequences of moderate PAE on social behavior, tongue protrusion, and flexibility in a variant of the Morris water task that required modification of a well-established spatial response. PAE rats displayed deficits in tongue protrusion, reduced flexibility in the spatial domain, increased wrestling, and decreased investigation, indicating that several behaviors associated with ventrolateral frontal cortex function are impaired following moderate PAE. A linear discriminant analysis revealed that measures of wrestling and tongue protrusion provided the best discrimination of PAE rats from saccharin-exposed control rats. We also evaluated all behaviors in young adult (4-5 months) or older (10-11 months) rats to address the persistence of behavioral deficits in adulthood and possible interactions between early ethanol exposure and advancing age. Behavioral deficits in each domain persisted well into adulthood (10-11 months), however, there was no evidence that aging enhances the effects of moderate PAE within the age ranges that were studied. PMID:24769174

  18. Aging behavior and life prediction of graphite composites

    NASA Technical Reports Server (NTRS)

    Ramohalli, Kumar; Raasch, David

    1989-01-01

    This paper presents experimental data from two independent tests, designed to determine the long-term reliability of composite materials. The technique of accelerated aging at elevated temperatures is employed. In the first set, graphite fiber, epoxy composites in five ply layups are manufactured and tested in the standard short-beam shear mode. In the second set, Nomex honeycomb, graphite fiber/epoxy composite face and rear sheet sandwich coupons are tested. After satisfying simple consistency checks, data interpretation is attempted within the framework of an Arrhenius degradation model. The elevated temperature is assumed to influence the degradation according to this temperature-dependent rate law. From these tests on five-ply composites and honeycomb sandwiches, it is concluded that aging is not a serious problem.

  19. Behavior of Fe-ODS Alloys After Thermal Aging Treatments

    NASA Astrophysics Data System (ADS)

    Serrano Garcia, Marta; Hernández-Mayoral, Mercedes; Esparraguera, Elvira Oñorbe

    2016-03-01

    Oxide dispersion alloys are one of the candidates as cladding materials for Gen IV fast reactors, due to their high strength at high temperature, good creep properties, and swelling resistance. This good performance is mainly due to a fine dispersion of nano-oxide particles on the microstructure and to non-grained structure. The microstructural stability and the mechanical properties of a Fe-ODS alloy are studied after different thermal aging experiments at 973 K (700 °C), 5000 hours; 973 K (700 °C), 10,000 hours; and 1123 K (850 °C), 10,000 hours. SEM/EBSD and TEM together with tensile and impact tests on the as-received and thermally aged material have been carried out. In general, for all the tested conditions, a slight softening effect is observed attributed to the changes in the grain structure as well as to the changes in the amount and size of nano-oxide particles. In addition, the aged material shows a lower impact USE value while the DBTT is maintained.

  20. Behavior of Fe-ODS Alloys After Thermal Aging Treatments

    NASA Astrophysics Data System (ADS)

    Serrano Garcia, Marta; Hernández-Mayoral, Mercedes; Esparraguera, Elvira Oñorbe

    2016-06-01

    Oxide dispersion alloys are one of the candidates as cladding materials for Gen IV fast reactors, due to their high strength at high temperature, good creep properties, and swelling resistance. This good performance is mainly due to a fine dispersion of nano-oxide particles on the microstructure and to non-grained structure. The microstructural stability and the mechanical properties of a Fe-ODS alloy are studied after different thermal aging experiments at 973 K (700 °C), 5000 hours; 973 K (700 °C), 10,000 hours; and 1123 K (850 °C), 10,000 hours. SEM/EBSD and TEM together with tensile and impact tests on the as-received and thermally aged material have been carried out. In general, for all the tested conditions, a slight softening effect is observed attributed to the changes in the grain structure as well as to the changes in the amount and size of nano-oxide particles. In addition, the aged material shows a lower impact USE value while the DBTT is maintained.

  1. Adrafinil: effects on behavior and cognition in aged canines.

    PubMed

    Siwak, C T; Callahan, H; Milgram, N W

    2000-07-01

    1. Adrafmil is a novel vigilance promoting agent developed in France by Louis Lafon Laboratories. 2. Adrafinil causes increased locomotion without producing stereotypical activity in canines tested in an open field. 3. The effectiveness of a single treatment is long-lasting, and the effectiveness persists over repeated treatments. 4. Acquisition of a size discrimination problem is enhanced by adrafinil. This may be linked to performance motivation. 5. Adrafinil causes a long-lasting increase in high frequency electroencephalographic activity recorded from cortical electrodes. 6. These results indicate that adrafinil is novel behavioral stimulant with cognitive enhancing potential. The underlying mechanisms of action are still unknown. PMID:11191710

  2. Kids, candy, brain and behavior: age differences in responses to candy gains and losses.

    PubMed

    Luking, Katherine R; Luby, Joan L; Barch, Deanna M

    2014-07-01

    The development of reward-related neural systems, from adolescence through adulthood, has received much recent attention in the developmental neuroimaging literature. However, few studies have investigated behavioral and neural responses to both gains and losses in pre-pubertal child populations. To address this gap in the literature, in the present study healthy children aged 7-11 years and young-adults completed an fMRI card-guessing game using candy pieces delivered post-scan as an incentive. Age differences in behavioral and neural responses to candy gains/losses were investigated. Adults and children displayed similar responses to gains, but robust age differences were observed following candy losses within the caudate, thalamus, insula, and hippocampus. Interestingly, when task behavior was included as a factor in post hoc mediation analyses, activation following loss within the caudate/thalamus related to task behavior and relationships with age were no longer significant. Conversely, relationships between response to loss and age within the hippocampus and insula remained significant even when controlling for behavior, with children showing heightened loss responses within the dorsal/posterior insula. These results suggest that both age and task behavior influence responses within the extended reward circuitry, and that children seem to be more sensitive than adults to loss feedback particularly within the dorsal/posterior insula. PMID:24534632

  3. Scintillation-Hardened GPS Receiver

    NASA Technical Reports Server (NTRS)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  4. Surface Fatigue Resistance with Induction Hardening

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis; Turza, Alan; Chapman, Mike

    1996-01-01

    Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

  5. Age differences in the Attention Network Test: Evidence from behavior and event-related potentials.

    PubMed

    Williams, Ryan S; Biel, Anna Lena; Wegier, Pete; Lapp, Leann K; Dyson, Benjamin J; Spaniol, Julia

    2016-02-01

    The Attention Network Test (ANT) is widely used to capture group and individual differences in selective attention. Prior behavioral studies with younger and older adults have yielded mixed findings with respect to age differences in three putative attention networks (alerting, orienting, and executive control). To overcome the limitations of behavioral data, the current study combined behavioral and electrophysiological measures. Twenty-four healthy younger adults (aged 18-29years) and 24 healthy older adults (aged 60-76years) completed the ANT while EEG data were recorded. Behaviorally, older adults showed reduced alerting, but did not differ from younger adults in orienting or executive control. Electrophysiological components related to alerting and orienting (P1, N1, and CNV) were similar in both age groups, whereas components related to executive control (N2 and P3) showed age-related differences. Together these results suggest that comparisons of network effects between age groups using behavioral data alone may not offer a complete picture of age differences in selective attention, especially for alerting and executive control networks. PMID:26760449

  6. Behavioral and Emotional Problems Reported by Parents of Children Ages 6 to 16 in 31 Societies

    ERIC Educational Resources Information Center

    Rescorla, Leslie; Achenbach, Thomas; Ivanova, Masha Y.; Dumenci, Levent; Almqvist, Fredrik; Bilenberg, Niels; Bird, Hector; Chen, Wei; Dobrean, Anca; Dopfner, Manfred; Erol, Nese; Fombonne, Eric; Fonseca, Antonio; Frigerio, Alessandra; Grietens, Hans; Hannesdottir, Helga; Kanbayashi, Yasuko; Lambert, Michael; Larsson, Bo; Leung, Patrick; Liu, Xianchen; Minaei, Asghar; Mulatu, Mesfin S.; Novik, Torunn S.; Oh, Kyung-Ja; Roussos, Alexandra; Sawyer, Michael; Simsek, Zeynep; Steinhausen, Hans-Christoph; Weintraub, Sheila; Weisz, John; Metzke, Christa Winkler; Wolanczyk, Tomasz; Yang, Hao-Jan; Zilber, Nelly; Zukauskiene, Rita; Verhulst, Frank

    2007-01-01

    This study compared parents' ratings of behavioral and emotional problems on the "Child Behavior Checklist" (Achenbach, 1991; Achenbach & Rescorla, 2001) for general population samples of children ages 6 to 16 from 31 societies (N = 55,508). Effect sizes for society ranged from 0.03 to 0.14. Effect sizes for gender were less than or equal to 0.01,…

  7. Health Promoting Behaviors of Older Americans versus Young and Middle Aged Adults

    ERIC Educational Resources Information Center

    Becker, Craig; Arnold, William

    2004-01-01

    Health promoting behaviors have become increasingly important as Americans attempt to retain their youth and health. This study collected self-reported data from 559 participants in the Southwest United States using the Health Promoting Lifestyle Profile II to compare the health promoting behaviors of older adults (60-92 years), middle-aged adults…

  8. Health Promoting Behaviors of Older Americans Versus Young and Middle Aged Adults

    ERIC Educational Resources Information Center

    Becker, Craig M.; Arnold, William

    2004-01-01

    Health promoting behaviors have become increasingly important as Americans attempt to retain their youth and health. This study collected self-reported data from 559 participants in the Southwest United States using the Health Promoting Lifestyle Profile II to compare the health promoting behaviors of older adults (60-92 years), middle-aged adults…

  9. Childhood Fears, Neurobehavioral Functioning and Behavior Problems in School-Age Children

    ERIC Educational Resources Information Center

    Kushnir, Jonathan; Sadeh, Avi

    2010-01-01

    The objective is to examine underlying associations between childhood fears, behavior problems and neurobehavioral functioning (NBF) in school-age children. Healthy, regular school children (N = 135), from second, fourth and sixth grade classes were assessed. Data regarding children's fears and behavioral problems were obtained with the Revised…

  10. Early Development of Stereotyped and Self-Injurious Behaviors: II. Age Trends.

    ERIC Educational Resources Information Center

    Berkson, Gershon

    2002-01-01

    A longitudinal study of 39 infants who engaged in stereotyped or self-injurious behaviors that were served in early intervention programs found these behaviors increased and declined over age more slowly than in typical babies. Head-banging seemed to be related to tantrums, whereas eye-poking developed early and seemed to be self-stimulatory.…

  11. Pupillary behavior in relation to wavelength and age.

    PubMed

    Lobato-Rincón, Luis-Lucio; Cabanillas-Campos, Maria Del Carmen; Bonnin-Arias, Cristina; Chamorro-Gutiérrez, Eva; Murciano-Cespedosa, Antonio; Sánchez-Ramos Roda, Celia

    2014-01-01

    Pupil light reflex can be used as a non-invasive ocular predictor of cephalic autonomic nervous system integrity. Spectral sensitivity of the pupil's response to light has, for some time, been an interesting issue. It has generally, however, only been investigated with the use of white light and studies with monochromatic wavelengths are scarce. This study investigates the effects of wavelength and age within three parameters of the pupil light reflex (amplitude of response, latency, and velocity of constriction) in a large sample of younger and older adults (N = 97), in mesopic conditions. Subjects were exposed to a single light stimulus at four different wavelengths: white (5600°K), blue (450 nm), green (510 nm), and red (600 nm). Data was analyzed appropriately, and, when applicable, using the General Linear Model (GLM), Randomized Complete Block Design (RCBD), Student's t-test and/or ANCOVA. Across all subjects, pupillary response to light had the greatest amplitude and shortest latency in white and green light conditions. In regards to age, older subjects (46-78 years) showed an increased latency in white light and decreased velocity of constriction in green light compared to younger subjects (18-45 years old). This study provides data patterns on parameters of wavelength-dependent pupil reflexes to light in adults and it contributes to the large body of pupillometric research. It is hoped that this study will add to the overall evaluation of cephalic autonomic nervous system integrity. PMID:24795595

  12. Pupillary behavior in relation to wavelength and age

    PubMed Central

    Lobato-Rincón, Luis-Lucio; Cabanillas-Campos, Maria del Carmen; Bonnin-Arias, Cristina; Chamorro-Gutiérrez, Eva; Murciano-Cespedosa, Antonio; Sánchez-Ramos Roda, Celia

    2014-01-01

    Pupil light reflex can be used as a non-invasive ocular predictor of cephalic autonomic nervous system integrity. Spectral sensitivity of the pupil's response to light has, for some time, been an interesting issue. It has generally, however, only been investigated with the use of white light and studies with monochromatic wavelengths are scarce. This study investigates the effects of wavelength and age within three parameters of the pupil light reflex (amplitude of response, latency, and velocity of constriction) in a large sample of younger and older adults (N = 97), in mesopic conditions. Subjects were exposed to a single light stimulus at four different wavelengths: white (5600°K), blue (450 nm), green (510 nm), and red (600 nm). Data was analyzed appropriately, and, when applicable, using the General Linear Model (GLM), Randomized Complete Block Design (RCBD), Student's t-test and/or ANCOVA. Across all subjects, pupillary response to light had the greatest amplitude and shortest latency in white and green light conditions. In regards to age, older subjects (46–78 years) showed an increased latency in white light and decreased velocity of constriction in green light compared to younger subjects (18–45 years old). This study provides data patterns on parameters of wavelength-dependent pupil reflexes to light in adults and it contributes to the large body of pupillometric research. It is hoped that this study will add to the overall evaluation of cephalic autonomic nervous system integrity. PMID:24795595

  13. The Effects of Music on Age Group Swimmers' Motivation and Practice Behavior.

    ERIC Educational Resources Information Center

    Stoeckel, Bryan D.

    This study examined the effects of music on the motivation of 22 female and 5 male swimmers ages 10-13 years. These age-group swimmers practiced 2.0-2.5 hours per day and had six training sessions per week. Using observation logs, surveys, and open-ended questions, the study analyzed swimmers' perceptions of, and behavior when, listening to music…

  14. Adaptive Behavior and Cognitive Function of Adults with Down Syndrome: Modeling Change with Age.

    ERIC Educational Resources Information Center

    Hawkins, Barbara A.; Eklund, Susan J.; James, David R.; Foose, Alice K.

    2003-01-01

    Fifty-eight adults with Down syndrome were assessed longitudinally over 10 years for the purpose of modeling aging-related change in cognitive function and adaptive behavior. Findings provide further evidence of changes in performance with age and include selected effects for participants who completed the study and those lost to follow-up.…

  15. Aging behavior of polymeric solar absorber materials - Part 1: Engineering plastics

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.

    2010-09-15

    In this series of two papers, various polymeric materials are investigated as to their potential applicability as absorber materials for solar thermal collectors. The focus of the investigation is to study the aging behavior of these materials under maximum operating conditions (80 C in water up to 16,000 h) and stagnation conditions (140 C in air up to 500 h) typical for northern climate. The materials supplied or produced as polymer films were first characterized in the unaged state and then for different states of aging by differential scanning calorimetry (DSC), by size exclusion chromatography (SEC) and by mechanical tensile tests. Physical aging phenomena were studied by DSC, SEC analysis provided information on chemical degradation of the materials. In addition, physical and chemical aging were both analyzed via the small and large strain mechanical behavior. While the present Part 1 of this paper series deals with the aging behavior of engineering plastics, including two amorphous polymers (a polyphenylene ether polystyrene blend (PPE + PS) and polycarbonate (PC)) and two semi-crystalline polymers (two types of polyamide 12 (PA12)), the aging behavior of so-called ''commodity'' plastics (PE and PP) is the subject of Part 2. Comparing the two aging conditions, the amorphous materials (PPE + PS and PC) turned out to be more prone to physical and chemical aging at 140 C in air. In contrast, the semi-crystalline PA12 materials were more strongly affected by exposure to water at 80 C, although to different degrees, depending on the modification. (author)

  16. [Phototactic behavior of Acheta domestica and Musca domestica in relation to aging processes].

    PubMed

    Stoll, S; Blösch, M; Kleider, H

    1990-01-01

    Individual phototactical behavior with age depends on sex and temperature in Acheta domesticus; its running time increases continually with age, whereas Musca domestica exhibits a minimum in young animals. There may be a connection in the mortality kinetics of populations of these insects. PMID:2392873

  17. Attachment Style, Home-Leaving Age and Behavioral Problems among Residential Care Children

    ERIC Educational Resources Information Center

    Shechory, Mally; Sommerfeld, Eliane

    2007-01-01

    In a prospective study, the attachment style, home-leaving age, length of time in residential care, and behavioral problems among Israeli residential care children (N=68), were studied. Data analyses showed that children removed from their homes at a later age suffered from higher levels of anxiety, depression and social problems compared to…

  18. Hardening and yielding in colloidal gels

    NASA Astrophysics Data System (ADS)

    Del Gado, Emanuela; Colombo, Jader; Bouzid, Mehdi

    Attractive colloidal gel networks are disordered elastic solids that can form even in extremely dilute particle suspensions. With interaction strengths comparable to the thermal energy, their stress-bearing network can locally restructure via breaking and reforming inter-particle bonds. We use molecular dynamics simulations of a model system to investigate the strain hardening and the yielding process. During shear start up protocol, the system exhibits strong localization of tensile stresses that may be released through the breaking and formation of new bonds. In this regime, the small amplitude oscillatory shear analysis shows that the storage and the loss modulus follow a power law behavior that are closely reminiscent of experimental observations. At large accumulated strains, the strain-induced reorganization of the gel may trigger flow heterogeneities and eventually lead to the yielding of the gel via a quasi brittle damage of its structure.

  19. Dilatant hardening of fluid-saturated sandstone

    NASA Astrophysics Data System (ADS)

    Makhnenko, Roman Y.; Labuz, Joseph F.

    2015-02-01

    The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response. Confined compression experiments, both conventional triaxial and plane strain, were performed on water-saturated Berea sandstone to investigate poroelastic and inelastic behavior. Measured drained response was used to calibrate an elasto-plastic constitutive model that predicts undrained inelastic deformation. The experimental data show good agreement with the model: dilatant hardening in undrained triaxial and plane strain compression tests under constant mean stress was predicted and observed.

  20. Precipitation hardening in a dental low-gold alloy.

    PubMed

    Kim, Hyung-Il; Park, Young-Hwan; Lee, Hee-Kyung; Seol, Hyo-Joung; Shiraishi, Takanobu; Hisatsune, Kunihiro

    2003-03-01

    Age-hardening characteristics in a dental low-gold alloy composed of 40.0 wt% Au-35.0 wt% Ag-7.9 wt% Pd-7.0 wt% Cu-5.0 wt% In-3.5 wt% Zn-1.5 wt% Sn, were investigated by means of the hardness test, XRD study, SEM observations and EPMA. The following results were obtained. The age-hardening was characterized by a precipitation of Cu-rich alpha2 phase in the a phase. The softening that occurred following prolonged ageing was due to the heterogeneous formation of the fine nodular precipitates composed of the Ag-rich alpha1 phase and the Cu-rich alpha2 phase at the grain boundaries of the a phase. PMID:12790292

  1. Beliefs About Behavior Account for Age Differences in the Correspondence Bias

    PubMed Central

    Blanchard-Fields, Fredda

    2011-01-01

    Objectives. Older adults tend to exhibit the correspondence bias to a greater extent than young adults. The current study examined whether these age differences are a function of the degree to which an individual subscribes to a lay theory of attitude–behavior consistency. Methods. First, participants responded to questions regarding their beliefs about attitude–behavior consistency. Approximately 2 weeks later, 144 (67 young adults and 77 older adults) participants completed the correspondence bias task. Results. As expected, older adults were more biased than young adults. Analyses revealed that the degree to which an individual holds attitude–behavior consistency beliefs in the dishonesty domain accounted for age-related differences in the correspondence bias. Discussion. The results of this study suggest that age differences in the correspondence bias task are in part driven by older adults holding stronger attitude–behavior consistency beliefs than young adults. PMID:21071624

  2. Who Should Report Abnormal Behavior at Preschool Age? The Case of Behavioral Inhibition

    ERIC Educational Resources Information Center

    Ballespi, Sergi; Jane, Ma Claustre; Riba, Ma Dolors

    2012-01-01

    Children who are behaviorally "inhibited"--a condition at the extreme of the behavioral inhibition dimension--experience distress in uncertain social situations. Although parents and teachers are in the best position to detect this condition, they rarely agree. This study aims to analyze the agreement between parents and teachers and to examine…

  3. Aging and the Effects of Exploratory Behavior on Spatial Memory.

    PubMed

    Varner, Kaitlin M; Dopkins, Stephen; Philbeck, John W

    2016-03-01

    The present research examined the effect of encoding from multiple viewpoints on scene recall in a group of younger (18-22 years) and older (65-80 years) adults. Participants completed a visual search task, during which they were given the opportunity to examine a room using two sets of windows that partitioned the room differently. Their choice of window set was recorded, to determine whether an association between these choices and spatial memory performance existed. Subsequently, participants were tested for spatial memory of the domain in which the search task was completed. Relative to younger adults, older adults demonstrated an increased tendency to use a single set of windows as well as decreased spatial memory for the domain. Window-set usage was associated with spatial memory, such that older adults who relied more heavily on a single set of windows also had better performance on the spatial memory task. These findings suggest that, in older adults, moderation in exploratory behavior may have a positive effect on memory for the domain of exploration. PMID:26758675

  4. Consistency condition for isotropic-kinematic hardening of anisotropic yield functions

    NASA Astrophysics Data System (ADS)

    Chung, Kwansoo

    2013-05-01

    For the combined type isotropic-kinematic hardening law to account for the Bauschinger, transient and permanent softening behaviors observed in reverse loading, formulations have been initially developed for isotropic yield functions, mainly based on the von Mises criterion, and then later extended for anisotropic yield functions. Among the efforts to introduce anisotropic yield functions to the combined type hardening formulation, however, some inconsistency has been encountered in manipulating the kinematic hardening law, especially for the nonlinear type law, even though their von Mises yield function versions have been consistent. Therefore, theoretical clarification and clearance of such inconsistency were attempted in this work by imposing the following (consistency) condition: the combined type hardening law is expected to behave the same as the full isotropic hardening for monotonously proportional loading, regardless of (anisotropic) yield functions coupled with the combined type hardening law. An example to account for the anisotropic hardening of an anisotropic yield function utilizing the combined type hardening law, but for which the consistency condition was partially released, was also demonstrated.

  5. The Predictive Utility of Early Childhood Disruptive Behaviors for School-Age Social Functioning

    PubMed Central

    Shaw, Daniel S.; Dishion, Thomas J.; Wilson, Melvin N.

    2016-01-01

    Research suggests that school-age children with disruptive behavior (DB) problems frequently demonstrate impaired social skills and experience rejection from peers, which plays a crucial role in the pathway to more serious antisocial behavior. A critical question is which DB problems in early childhood are prognostic of impaired social functioning in school-age children. This study examines the hypothesis that aggression in early childhood will be the more consistent predictor of compromised social functioning than inattentive, hyperactive-impulsive, or oppositional behavior. Participants included an ethnically diverse sample of 725 high-risk children from 3 geographically distinct areas followed from ages 2 to 8.5. Four latent growth models of DB from child ages 2 to 5, and potential interactions between dimensions, were used to predict latent parent and teacher ratings of school-age social dysfunction. Analyses were conducted in a multi-group format to examine potential differences between intervention and control group participants. Results showed that age 2 aggression was the DB problem most consistently associated with both parent- and teacher-rated social dysfunction for both groups. Early starting aggressive behavior may be particularly important for the early identification of children at risk for school-age social difficulties. PMID:25526865

  6. Effects of Aging Treatments on the Mechanical Behavior of Ti-15V-3Cr-3Sn-3Al Alloy

    NASA Astrophysics Data System (ADS)

    Chou, Y.-K.; Tsay, L. W.; Chen, C.

    2015-09-01

    The effect of aging treatments on the mechanical properties and microstructures of Ti-15V-3Cr-3Sn-3Al (Ti-15-3) alloy was evaluated using tensile, notched tensile, and J-integral tests. The properties for the one-step aged specimens (371 to 648 °C for 8 h) were compared with those for the two-step aged specimens (one-step aged + 426 °C/24 h). An increase in aging temperature of one-step aging resulted in increased notched tensile strength and fracture toughness of the Ti-15-3 alloy. The second-step aging at 426 °C for 24 h caused various degrees of hardening in the group of double aged specimens. Comparing to the one-step aged specimens, increased notch brittleness and decreased fracture toughness were observed in the two-step aged specimens. For the specimens subjected to aging at 648 °C, the formation of thick α layer at β grain boundaries resulted in lower tensile properties and fracture toughness. The fracture modes of the notch-brittle specimens were strongly affected by the distribution, size, and morphology of the α precipitates.

  7. Homeostatic and injury-induced microglia behavior in the aging brain

    PubMed Central

    Hefendehl, Jasmin K; Neher, Jonas J; Sühs, Rafael B; Kohsaka, Shinichi; Skodras, Angelos; Jucker, Mathias

    2014-01-01

    Microglia cells are essential for brain homeostasis and have essential roles in neurodegenerative diseases. Aging is the main risk factor for most neurodegenerative diseases, and age-related changes in microglia may contribute to the susceptibility of the aging brain to dysfunction and neurodegeneration. We have analyzed morphology and dynamic behavior of neocortical microglia in their physiological environment in young adult (3-month-old), adult (11- to 12-month-old), and aged (26- to 27-month-old) C57BL/6J-Iba1-eGFP mice using in vivo 2-photon microscopy. Results show that surveying microglial cells in the neocortex exhibit age-related soma volume increase, shortening of processes, and loss of homogeneous tissue distribution. Furthermore, microglial process speed significantly decreased with age. While only a small population of microglia showed soma movement in adult mice, the microglia population with soma movement was increased in aged mice. However, in response to tissue injury, the dynamic microglial response was age-dependently diminished. These results provide novel insights into microglial behavior and indicate that microglial dysfunction in the aging brain may contribute to age-related cognitive decline and neurodegenerative diseases. PMID:23953759

  8. A vulnerable age: environment, behavior and the spread of diarrhoea.

    PubMed

    1986-09-01

    In Bangladesh diarrhea occurs most often in children between the ages of 6-11 months. Crawling infants in rural areas come into contact with chicken feces and other animal dung on the ground both inside and outside the home. Additionally, the ground is contaminated with the baby's own feces and those of its brothers and sisters. Many infants put earth and feces in their mouths and most suck their fingers, which have touched and will pass on germs and fecal matter. Infants in 2 villages near Dhaka were found to have high rates of illness and malnutrition. Those whose families were poor and did not own land were affected more severely; they had worse malnutrition and a higher incidence of diarrhea. In both villages most infants were put down to play for most of the day. Most mothers said they rarely or never put a mat or jute sack down for their baby to lie on or crawl around on, and only a third of mothers were able to watch their babies continuously. The ground on which these infants were crawling was found to be highly contaminated. It was learned that while most mothers knew that feces were dirty, they were unaware that feces can cause disease. Poor traditional weaning practices and poor food hygiene also contributed to high attack rates of diarrhea. Basic messages and a range of interventions to improve traditional hygiene and health care practices were developed. First, mothers need to understand about germs and the fact that these cause diseases. Local materials and ideas were used to demonstrate this to a mainly illiterate audience. Interventions to keep the baby from touching and eating feces include: sweeping the baby's play area 4 times a day; using a dirt disposer, like a trowel, to remove feces from the ground; using a covered pit or latrine to dispose of feces; using a special place for disposing of garbage; and keeping crawling infants in a playpen. Interventions to reduce transmission of germs include: washing hands with ashes or soap after defecating

  9. Does early establishment of favorable oral health behavior influence caries experience at age 5 years?

    PubMed Central

    Wigen, Tove I.; Wang, Nina J.

    2015-01-01

    Objective The purpose was to study associations between tooth brushing frequency, use of fluoride lozenges and consumption of sugary drinks at 1.5 year of age and having caries experience at 5 years of age. Methods This study was based on data from the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health and by the Public Dental Services. A total of 1095 children were followed from pregnancy to the age of 5 years. Questionnaires regarding oral health behavior were completed by the parents at 1.5 and 5 years of age. Clinical and radiographic examination of the children was performed at the age of 5 years. Results In multiple logistic regression, having caries experience at 5 years of age was associated with; at 1.5 year of age having the teeth brushed less than twice daily (OR 2.1, CI 1.3–3.6) and being offered sugary drinks at least once a week (OR 1.8, CI 1.1–2.9) when controlled for family characteristics and oral health behavior at 5 years of age. Conclusions Tooth brushing frequency and consumption of sugary drinks in early childhood were related to caries development during preschool age independent of family characteristics and oral health behavior at 5 years of age. The results indicate that early established habits regarding tooth brushing and consumption of sugary drinks have long term effects on caries development. Parents encountering difficulties in establishing favorable oral health behavior in children’s first years of life should receive special attention from health personnel. PMID:25385683

  10. Aging behavior of polymeric solar absorber materials - Part 2: Commodity plastics

    SciTech Connect

    Kahlen, S.; Wallner, G.M.; Lang, R.W.

    2010-09-15

    In this series of two papers, various polymeric materials are investigated as to their potential applicability as absorber materials for solar thermal collectors. While Part 1 of this paper series deals with the aging behavior of engineering plastics, including two amorphous polymers (PPE + PS) and (PC) and two semi-crystalline polymers (two types of PA12), the present Part 2 treats the aging behavior of semi-crystalline so-called ''commodity'' plastics (two types of crosslinked polyethylene (PE-X) and two types of polypropylene (PP)). As in Part 1, the focus of the investigation is to study the aging behavior of these materials under maximum operating conditions (80 C in water up to 16,000 h) and stagnation conditions (140 C in air up to 500 h) typical for northern climate. The materials supplied or produced as polymer films were first characterized in the unaged state and then for different states of aging by differential scanning calorimetry (DSC), by size exclusion chromatography (SEC) and by mechanical tensile tests. DSC was applied primarily to obtain information on physical aging phenomena, whereas SEC analysis was used to characterize chemical degradation of the materials. In addition, physical and chemical aging were both analyzed via the small and large strain mechanical behavior. Comparing the two aging conditions in hot air and hot water, a rather stable mechanical performance profile was found for both PP types over the investigated aging time, which was interpreted in terms of competing physical and chemical aging mechanisms. Analogously such competing mechanisms were also inferred for one of the PE-X materials, while the other exhibited substantial degradation in terms of strain-to-break values for both aging conditions. In principle, both PP and PE-X are promising candidates for black absorber applications in northern climates if proper measures against overheating are taken and when adequately modified. (author)

  11. Age-related striatal BOLD changes without changes in behavioral loss aversion

    PubMed Central

    Viswanathan, Vijay; Lee, Sang; Gilman, Jodi M.; Kim, Byoung Woo; Lee, Nick; Chamberlain, Laura; Livengood, Sherri L.; Raman, Kalyan; Lee, Myung Joo; Kuster, Jake; Stern, Daniel B.; Calder, Bobby; Mulhern, Frank J.; Blood, Anne J.; Breiter, Hans C.

    2015-01-01

    Loss aversion (LA), the idea that negative valuations have a higher psychological impact than positive ones, is considered an important variable in consumer research. The literature on aging and behavior suggests older individuals may show more LA, although it is not clear if this is an effect of aging in general (as in the continuum from age 20 and 50 years), or of the state of older age (e.g., past age 65 years). We also have not yet identified the potential biological effects of aging on the neural processing of LA. In the current study we used a cohort of subjects with a 30 year range of ages, and performed whole brain functional MRI (fMRI) to examine the ventral striatum/nucleus accumbens (VS/NAc) response during a passive viewing of affective faces with model-based fMRI analysis incorporating behavioral data from a validated approach/avoidance task with the same stimuli. Our a priori focus on the VS/NAc was based on (1) the VS/NAc being a central region for reward/aversion processing; (2) its activation to both positive and negative stimuli; (3) its reported involvement with tracking LA. LA from approach/avoidance to affective faces showed excellent fidelity to published measures of LA. Imaging results were then compared to the behavioral measure of LA using the same affective faces. Although there was no relationship between age and LA, we observed increasing neural differential sensitivity (NDS) of the VS/NAc to avoidance responses (negative valuations) relative to approach responses (positive valuations) with increasing age. These findings suggest that a central region for reward/aversion processing changes with age, and may require more activation to produce the same LA behavior as in younger individuals, consistent with the idea of neural efficiency observed with high IQ individuals showing less brain activation to complete the same task. PMID:25983682

  12. Age-related striatal BOLD changes without changes in behavioral loss aversion.

    PubMed

    Viswanathan, Vijay; Lee, Sang; Gilman, Jodi M; Kim, Byoung Woo; Lee, Nick; Chamberlain, Laura; Livengood, Sherri L; Raman, Kalyan; Lee, Myung Joo; Kuster, Jake; Stern, Daniel B; Calder, Bobby; Mulhern, Frank J; Blood, Anne J; Breiter, Hans C

    2015-01-01

    Loss aversion (LA), the idea that negative valuations have a higher psychological impact than positive ones, is considered an important variable in consumer research. The literature on aging and behavior suggests older individuals may show more LA, although it is not clear if this is an effect of aging in general (as in the continuum from age 20 and 50 years), or of the state of older age (e.g., past age 65 years). We also have not yet identified the potential biological effects of aging on the neural processing of LA. In the current study we used a cohort of subjects with a 30 year range of ages, and performed whole brain functional MRI (fMRI) to examine the ventral striatum/nucleus accumbens (VS/NAc) response during a passive viewing of affective faces with model-based fMRI analysis incorporating behavioral data from a validated approach/avoidance task with the same stimuli. Our a priori focus on the VS/NAc was based on (1) the VS/NAc being a central region for reward/aversion processing; (2) its activation to both positive and negative stimuli; (3) its reported involvement with tracking LA. LA from approach/avoidance to affective faces showed excellent fidelity to published measures of LA. Imaging results were then compared to the behavioral measure of LA using the same affective faces. Although there was no relationship between age and LA, we observed increasing neural differential sensitivity (NDS) of the VS/NAc to avoidance responses (negative valuations) relative to approach responses (positive valuations) with increasing age. These findings suggest that a central region for reward/aversion processing changes with age, and may require more activation to produce the same LA behavior as in younger individuals, consistent with the idea of neural efficiency observed with high IQ individuals showing less brain activation to complete the same task. PMID:25983682

  13. Natural aging and reversion behavior of Al-Cu-Li-Ag-Mg alloy Weldalite (tm) 049

    NASA Technical Reports Server (NTRS)

    Gayle, Frank W.; Heubaum, Frank H.; Pickens, Joseph R.

    1991-01-01

    This study was initiated to understand the natural aging and reversion behavior of Weldalite (trademark) 049 in tempers without cold work. Of particular interest are: (1) the microstructural basis for the high strength in the T4 condition; (2) an explanation of the reversion phenomenon; and (3) the effect of re-aging at room temperature after a reversion treatment. Mechanical properties were measured and transmission electron microscopy (TEM) analysis performed at various stages of microstructural development during aging, reversion, and subsequent re-aging.

  14. DISPERSION HARDENING OF URANIUM METAL

    DOEpatents

    Arbiter, W.

    1963-01-15

    A method of hardening U metal involves the forming of a fine dispersion of UO/sub 2/. This method consists of first hydriding the U to form a finely divided powder and then exposing the powder to a very dilute O gas in an inert atmosphere under such pressure and temperature conditions as to cause a thin oxide film to coat each particle of the U hydride, The oxide skin prevents agglomeration of the particles as the remaining H is removed, thus preserving the small particle size. The oxide skin coatings remain as an oxide dispersion. The resulting product may be workhardened to improve its physical characteristics. (AEC)

  15. Iron supplementation in infancy contributes to more adaptive behavior at 10 years of age.

    PubMed

    Lozoff, Betsy; Castillo, Marcela; Clark, Katy M; Smith, Julia B; Sturza, Julie

    2014-06-01

    Most studies of behavioral/developmental effects of iron deficiency anemia (IDA) or iron supplementation in infancy have found social-emotional differences. Differences could relate to behavioral inhibition or lack of positive affect and altered response to reward. To determine long-term behavioral effects, the study was a follow-up of a randomized controlled trial of behavioral/developmental effects of preventing IDA in infancy. Healthy Chilean infants free of IDA at age 6 mo were randomly assigned to iron supplementation or no added iron (formula with iron/powdered cow milk, vitamins with/without iron) from ages 6 to 12 mo. At age 10 y, 59% (666 of 1123) and 68% (366 of 534) of iron-supplemented and no-added-iron groups were assessed. Social-emotional outcomes included maternal-reported behavior problems, self-reported behavior, examiner ratings, and video coding of a social stress task and gamelike paradigms. Examiners rated the iron-supplemented group as more cooperative, confident, persistent after failure, coordinated, and direct and reality-oriented in speech and working harder after praise compared with the no-added-iron group. In a task designed to elicit positive affect, supplemented children spent more time laughing and smiling together with their mothers and started smiling more quickly. In the social stress task they smiled and laughed more and needed less prompting to complete the task. All P values were <0.05; effect sizes were 0.14-0.36. There were no differences in behaviors related to behavioral inhibition, such as anxiety/depression or social problems. In sum, iron supplementation in infancy was associated with more adaptive behavior at age 10 y, especially in affect and response to reward, which may improve performance at school and work, mental health, and personal relationships. PMID:24717366

  16. Cracking behavior of thermally aged and irradiated CF-8 cast austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Alexandreanu, B.; Chen, W.-Y.; Natesan, K.; Li, Z.; Yang, Y.; Rao, A. S.

    2015-11-01

    To assess the combined effect of thermal aging and neutron irradiation on the cracking behavior of CF-8 cast austenitic stainless steel, crack growth rate (CGR) and fracture toughness J-R curve tests were carried out on compact-tension specimens in high-purity water with low dissolved oxygen. Both unaged and thermally aged specimens were irradiated at ∼320 °C to 0.08 dpa. Thermal aging at 400 °C for 10,000 h apparently had no effect on the corrosion fatigue and stress corrosion cracking behavior in the test environment. The cracking susceptibility of CF-8 was not elevated significantly by neutron irradiation at 0.08 dpa. Transgranular cleavage-like cracking was the main fracture mode during the CGR tests, and a brittle morphology of delta ferrite was often seen on the fracture surfaces at the end of CGR tests. The fracture toughness J-R curve tests showed that both thermal aging and neutron irradiation can induce significant embrittlement. The loss of fracture toughness due to neutron irradiation was more pronounced in the unaged than aged specimens. After neutron irradiation, the fracture toughness values of the unaged and aged specimens were reduced to a similar level. G-phase precipitates were observed in the aged and irradiated specimens with or without prior aging. The similar microstructural changes resulting from thermal aging and irradiation suggest a common microstructural mechanism of inducing embrittlement in CF-8.

  17. Age-Dependent Changes in the Inflammatory Nociceptive Behavior of Mice

    PubMed Central

    King-Himmelreich, Tanya S.; Möser, Christine V.; Wolters, Miriam C.; Olbrich, Katrin; Geisslinger, Gerd; Niederberger, Ellen

    2015-01-01

    The processing of pain undergoes several changes in aging that affect sensory nociceptive fibers and the endogenous neuronal inhibitory systems. So far, it is not completely clear whether age-induced modifications are associated with an increase or decrease in pain perception. In this study, we assessed the impact of age on inflammatory nociception in mice and the role of the hormonal inhibitory systems in this context. We investigated the nociceptive behavior of 12-month-old versus 6–8-week-old mice in two behavioral models of inflammatory nociception. Levels of TRP channels, and cortisol as well as cortisol targets, were measured by qPCR, ELISA, and Western blot in the differently aged mice. We observed an age-related reduction in nociceptive behavior during inflammation as well as a higher level of cortisol in the spinal cord of aged mice compared to young mice, while TRP channels were not reduced. Among potential cortisol targets, the NF-κB inhibitor protein alpha (IκBα) was increased, which might contribute to inhibition of NF-κB and a decreased expression and activity of the inducible nitric oxide synthase (iNOS). In conclusion, our results reveal a reduced nociceptive response in aged mice, which might be at least partially mediated by an augmented inflammation-induced increase in the hormonal inhibitory system involving cortisol. PMID:26593904

  18. Energy-Efficient Thermomagnetic and Induction Hardening

    SciTech Connect

    2009-02-01

    This factsheet describes a research project that will develop and test a hybrid thermomagnetic and induction hardening technology to replace conventional heat treatment processes in forging applications.

  19. Radiation Hardened Electronics for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Watson, Michael D.

    2007-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

  20. Executive Function Mediates Effects of Gestational Age on Functional Outcomes and Behavior in Preschoolers

    PubMed Central

    Loe, Irene M.; Feldman, Heidi M.; Huffman, Lynne C.

    2014-01-01

    Objective To investigate the role of executive function (EF) skills, measured by parent-rating and performance-based instruments, as mediators of the effects of gestational age on functional outcomes and behavior symptoms in preterm and full term preschoolers. Patients and methods Children born preterm (n=70; mean gestational age 29.6 weeks and mean birth weight 1365g) were compared to children born full term (n=79) on composite measures of EF (using the Behavior Rating Inventory of Executive Function and a performance-based EF battery), adaptive function, prereading skills, and behavior symptoms. For the entire sample, mediation analyses examined the effect of gestational age on outcomes with EF as mediator. Results Compared to children born full term, children born preterm had significantly higher parent-rated EF scores and lower performance-based EF scores, both indicating more problems; further, children born preterm had lower adaptive function and prereading scores and more problematic behavior. Gestational age contributed to adaptive function, prereading skills, and behavior symptoms for all children. EF acted as a mediator of gestational age for all three outcomes; different patterns emerged for parent-rated and performance-based EF evaluations. For adaptive function, both EF measures significantly mediated effects of gestational age; for prereading skills, only performance-based EF was significant; for behavior symptoms, only parent-rated EF was significant. Conclusions We propose standard assessment of EF, using both parent-rating and performance-based EF measures, in young preterm children and other children at risk of EF impairments. EF skills are measurable, mediate important functional outcomes, and may serve as intervention targets. PMID:24906034

  1. COSMIC-RAY HELIUM HARDENING

    SciTech Connect

    Ohira, Yutaka; Ioka, Kunihito

    2011-03-01

    Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 10{sup 15}eV, and (2) all CR spectra become hard at {approx}>10{sup 11}eV nucleon{sup -1}. We propose a new idea, that higher energy CRs are generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium. The helium-to-proton ratio at {approx}100 TeV exceeds the Big Bang abundance Y = 0.25 by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in an energy-dependent way. We provide a simple analytical spectrum that also fits well the hardening due to the decreasing Mach number in the hot superbubble with {approx}10{sup 6} K. Our model predicts hard and concave spectra for heavier CR elements.

  2. Effect of thermal aging on the fatigue crack growth behavior of cast duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Lü, Xu-ming; Li, Shi-lei; Zhang, Hai-long; Wang, Yan-li; Wang, Xi-tao

    2015-11-01

    The effect of thermal aging on the fatigue crack growth (FCG) behavior of Z3CN20?09M cast duplex stainless steel with low ferrite content was investigated in this study. The crack surfaces and crack growth paths were analyzed to clarify the FCG mechanisms. The microstructure and micromechanical properties before and after thermal aging were also studied. Spinodal decomposition in the aged ferrite phase led to an increase in the hardness and a decrease in the plastic deformation capacity, whereas the hardness and plastic deformation capacity of the austenite phase were almost unchanged after thermal aging. The aged material exhibited a better FCG resistance than the unaged material in the near-threshold regime because of the increased roughness-induced crack closure associated with the tortuous crack path and rougher fracture surface; however, the tendency was reversed in the Paris regime because of the cleavage fracture in the aged ferrite phases.

  3. West Virginia Adolescents' Health Risk Behaviors: Differences by Gender, Age, Grade Level, and Level of Rurality.

    ERIC Educational Resources Information Center

    Meehan, Merrill L.; And Others

    In 1990, the Youth Risk Behavior Survey (YRBS) was completed by a random sample of 1,448 West Virginia public-school students in grades 9-12. The sample was 51 percent male and 89 percent white. About 71 percent of subjects were aged 15-17; 39 percent were in the ninth grade. The YRBS covered behaviors producing vehicle-related or other injuries,…

  4. Delayed Adulthood, Delayed Desistance? Trends in the Age Distribution of Problem Behaviors

    PubMed Central

    Hayford, Sarah R.; Furstenberg, Frank F.

    2009-01-01

    As the transition to adulthood becomes more protracted and less orderly, fewer young people occupy adult roles and experience the social control associated with these roles. One might therefore expect behaviors associated with the teenage years to spill over into older age groups, reflecting postponed entrance into full social adulthood. We test this hypothesis by examining trends over time in the age distribution of crime, substance use, and violent death. We find little evidence that behaviors typical of adolescence are moving upward to older ages. Although the achievement of adult roles is being pushed to older ages, this stretching of the transition to adulthood is not reflected in the observed patterns of substance use, violent death, and arrests. PMID:19633730

  5. The effect of physical aging on the crazing behavior of polystyrene

    SciTech Connect

    Gusler, G.M.; McKenna, G.B.

    1995-12-31

    In glassy polymers, failure is often preceded by polymer crazing, a process where voids are formed, separated by strands of oriented polymer called fibrils. Glassy polymers also undergo a structural recovery in which the enthalpy and volume of the glass evolve to the true equilibrium state. {open_quotes}Physical aging{close_quotes} refers to the changes in mechanical response associated with the structural recovery. It is expected that aging the polymer will impact the crazing behavior. This work investigates the critical strain for craze initiation, and the craze initiation time under equal bi-axial stress of a commercial polystyrene as a function of aging time and temperature. These experiments add to the limited database on the effect of physical aging on crazing behavior.

  6. Behavioral reinforcement of long-term potentiation is impaired in aged rats with cognitive deficiencies.

    PubMed

    Bergado, J A; Almaguer, W; Ravelo, J; Rosillo, J C; Frey, J U

    2001-01-01

    Behavioral stimuli with emotional/motivational content can reinforce long-term potentiation in the dentate gyrus, if presented within a distinct time window. A similar effect can be obtained by stimulating the basolateral amygdala, a limbic structure related to emotions. We have previously shown that aging impairs amygdala-hippocampus interactions during long-term potentiation. In this report we show that behavioral reinforcement of long-term potentiation is also impaired in aged rats with cognitive deficits. While among young water-deprived animals drinking 15 min after induction of long-term potentiation leads to a significant prolongation of potentiation, cognitively impaired aged rats are devoid of such reinforcing effects. In contrast, a slight but statistically significant depression develops after drinking in this group of animals. We suggest that an impaired mechanism of emotional/motivational reinforcement of synaptic plasticity might be functionally related to the cognitive deficits shown by aged animals. PMID:11738126

  7. Health Promotion Behaviors and Chronic Diseases of Aging in the Elderly People of Iranshahr*- IR Iran

    PubMed Central

    Mofrad, Zahra Pishkar; Jahantigh, Mozhgan; Arbabisarjou, Azizollah

    2016-01-01

    Introduction and Aim: Aging is considered as the phenomenon of the day in the health arena of the world and Iran. It is anticipated that there will be an explosion of aging population in Iran in about 2031 and 20-25% of the population will be aged over 60 years. With aging, chronic diseases also increase and diminish the functional ability of older people. On the other hand, increased healthcare costs should be also added to this issue. Health promotion is a concept of process that continues throughout life. As much as health promotion is important in children and adults, it is equally important in older people. In fact, the elderlies, as a group, also acquire many benefits from health promotion behaviors. Due to the increasing elderly population, geriatric health promotion and enhancing the health level of older people is proposed as a health priority that should be properly planned. Hence, the present study has been conducted in this regard and aims to identify behaviors of health promotion and chronic diseases of aging in the elderly people of Iranshahr-Iran. Materials and Methods: The present research is a cross-sectional descriptive study whose population consists of 425 elderly people aged 60 years and over, who lived in the city of Iranshahr*, IR Iran. The random cluster sampling method has been used to select the research samples. The required information was collected using a questionnaire which was distributed among the older people through visiting their homes; then, the collected data was statistically analyzed using the statistical software of SPSS version 13. Findings: The research findings show that the mean age of older people is 66.33 ± 7.7 and the highest frequency belongs to the age group of 60 years and the maximum age is 92 years. 69.5% of the older people were in the age group of the young elderly (60-69 years) and 44% of them lived with their married children; also 55.8%, 81.9%, 70.5%, and 74.4% of them were respectively female, illiterate

  8. Developing a self-reporting method to measure pedestrian behaviors at all ages.

    PubMed

    Granié, Marie-Axelle; Pannetier, Marjorie; Guého, Ludivine

    2013-01-01

    The objective of this study was to develop and validate a self-reporting scale to measure injury risk behaviors among pedestrians of all ages. The Pedestrian Behavior Scale (PBS) was developed that included 47 items enabling respondents to evaluate the frequency with which they had different types of pedestrian behaviors. The validation study was carried out on 343 participants (126 men and 217 women) between the ages of 15 and 78. Factor analyses were used to differentiate between 4 axes. Factor 1, "transgression", included items concerning offence of legal rules and errors. Factor 2 included "lapses" items. Factor 3 comprised "aggressive behavior" items and factor 4 included "positive behavior" items. A revised version of the PBS with 20 items was produced by selecting those items that loaded most strongly on the four factors. The 20-item version had good internal reliability. The effects of demographic and mobility variables on the PBS scores were investigated. This instrument will be useful in measuring the frequency of these different types of behaviors among the pedestrians who are most at risk, analyzing the psychological factors used to predict PBS scores and thus better adapt preventive actions to the different populations of vulnerable road users of all ages. PMID:22836115

  9. Comprehensively Assessing Cognitive and Behavioral Risks for HIV Infection among Middle-Aged and Older Adults

    ERIC Educational Resources Information Center

    Paniagua, Freddy A.; O'Boyle, Michael

    2008-01-01

    A comprehensive survey of HIV/AIDS with middle-aged and older adults should include six domains (e.g., factual knowledge regarding the acquisition and transmission of HIV, traditionally-accepted behavioral risks for HIV infection). A sample of 23 women (54.8%) and 19 men (45.2%), ranging in age from 51 to 85 were surveyed across such domains.…

  10. Effects of brain-derived neurotrophic factor on dopaminergic function and motor behavior during aging

    PubMed Central

    Boger, Heather A.; Mannangatti, Padmanabhan; Samuvel, Devadoss J.; Saylor, Alicia J.; Bender, Tara S.; McGinty, Jacqueline F.; Fortress, Ashley M.; Zaman, Vandana; Huang, Peng; Middaugh, Lawrence D.; Randall, Patrick K.; Jayanthi, Lankupalle D.; Rohrer, Baerbel; Helke, Kristi L.; Granholm, Ann-Charlotte; Ramamoorthy, Sammanda

    2010-01-01

    Brain-derived neurotrophic factor (BDNF) is critical in synaptic plasticity and in the survival and function of midbrain dopamine neurons. In the present study, we assessed the effects of a partial genetic deletion of BDNF on motor function and dopamine (DA) neurotransmitter measures by comparing (Bdnf+/−) with wildtype mice (WT) at different ages. Bdnf+/ and WT mice had similar body weights until 12 months of age; however, at 21 months, Bdnf+/− mice were significantly heavier than WT mice. Horizontal and vertical motor activity was reduced for Bdnf+/− compared to WT mice; but was not influenced by Age. Performance on an accelerating rotarod declined with age for both genotypes and was exacerbated for Bdnf+/− mice. Body weight did not correlate with any of the three behavioral measures studied. DA neurotransmitter markers indicated no genotypic difference in striatal tyrosine hydroxylase (TH), dopamine transporter (DAT), or vesicular monoamine transporter 2 (VMAT2) immunoreactivity at any age. However, DA transport via DAT (starting at 12 months) and VMAT2 (starting at 3 months) as well as KCl-stimulated DA release were reduced in Bdnf+/− mice and declined with age suggesting an increasingly important role for BDNF in the release and uptake of DA with the aging process. These findings suggest that a BDNF expression deficit becomes more critical to dopaminergic dynamics and related behavioral activities with increasing age. PMID:20860702

  11. Development of preterm infants: feeding behaviors and brazelton neonatal behavioral assessment scale at 40 and 44 weeks' postconceptional age.

    PubMed

    Medoff-Cooper, Barbara; Ratcliffe, Sarah J

    2005-01-01

    The purpose of this study was twofold: (1) to explore potential changes in the Brazelton Neonatal Behavioral Assessment Scale (BNBAS) from 40 to 44 weeks postconceptional age (PCA) and (2) to determine the relationship between the BNBAS scores and feeding behaviors in preterm infants at 40 and 44 weeks PCA. The BNBAS and sucking behavior measurements were completed on 104 preterm infants at 40 and 44 weeks PCA. The Orientation (p = .001), Motor (p = .001), Range of State (p = .001), Autonomic Regulation (p = .01), and Reflexes (p = .00) clusters were significantly more mature at 44 weeks PCA than at 40 weeks. Infants that were extremely early born (n = 24) had a significantly larger change in BNBAS scores over time as compared to the more mature preterm infants (n = 77), largely catching up with their more mature preterm counterparts. At 40 and 44 weeks PCA, the BNBAS cluster scores for orientation (p = .02), motor (p = .048), range of state (p = .048), and regulation of state (p < .001) were significantly related to the average maximum pressure, adjusted for gestational age and weeks PCA. Significant neurobehavioral maturation takes place between 40 and 44 weeks PCA in preterm infants, with the greatest changes occurring in the most preterm infants. These findings highlight the relationship between neurobehavioral maturation and feeding behaviors. PMID:16292021

  12. On the Precipitation Hardening of Selective Laser Melted AlSi10Mg

    NASA Astrophysics Data System (ADS)

    Aboulkhair, Nesma T.; Tuck, Chris; Ashcroft, Ian; Maskery, Ian; Everitt, Nicola M.

    2015-08-01

    Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.

  13. Effects of MAOA-Genotype, Alcohol Consumption, and Aging on Violent Behavior

    PubMed Central

    Tikkanen, Roope; Sjöberg, Rickard L.; Ducci, Francesca; Goldman, David; Holi, Matti; Tiihonen, Jari; Virkkunen, Matti

    2009-01-01

    Background Environmental factors appear to interact with a functional polymorphism (MAOA-LPR) in the promoter region of the monoamine oxidase A gene (MAOA) in determining some forms of antisocial behavior. However, how MAOA-LPR modulates the effects of other factors such as alcohol consumption related to antisocial behavior is not completely understood. Methods This study examines the conjunct effect of MAOA-LPR, alcohol consumption, and aging on the risk for violent behavior. Recidivism in severe impulsive violent behavior was assessed after 7 to 15 years in a sample of 174 Finnish alcoholic offenders, the majority of whom exhibited antisocial or borderline personality disorder or both, and featured impulsive temperament traits. Results The risk for committing new acts of violence increased by 2.3% for each kilogram of increase in yearly mean alcohol consumption (p = 0.004) and decreased by 7.3% for every year among offenders carrying the high activity MAOA genotype. In contrast, alcohol consumption and aging failed to affect violent behavior in the low activity MAOA genotyped offenders. MAOA-LPR showed no main effect on the risk for recidivistic violence. Conclusions Violent offenders carrying the high activity MAOA genotype differ in several ways from carriers with the low activity MAOA risk allele previously associated with antisocial behavior. Finnish high activity MAOA genotyped risk alcoholics exhibiting antisocial behavior, high alcohol consumption, and abnormal alcohol-related impulsive and uncontrolled violence might represent an etiologically distinct alcohol dependence subtype. PMID:19120058

  14. Impact of Inuit customary adoption on behavioral problems in school-age Inuit children.

    PubMed

    Decaluwe, Béatrice; Jacobson, Sandra W; Poirier, Marie-Andrée; Forget-Dubois, Nadine; Jacobson, Joseph L; Muckle, Gina

    2015-05-01

    A large proportion of Inuit children in Arctic Quebec are adopted in accordance with traditional Inuit customs. In contrast to adoptions in Southern Canada and the United States, the child is adopted at birth and by a close family member; he or she knows who his or her biological parents are, and will typically have contact with them. Studies of other populations have reported an increased incidence of behavior problems in adopted compared with nonadopted children. This study examined the actual extent of the increase in the number of behavior problems seen in Inuit children adopted in accordance with traditional customs. In a prospective longitudinal study conducted in the Canadian Arctic (n = 46 adopted and 231 nonadopted children), prenatal and familial variables were documented at birth and at school age (M = 11.3 years). Behavior problems were assessed on the Teacher Report Form of the Child Behavior Checklist. Adopted children lived in more economically disadvantaged families, but their caregivers were less prone to depression, domestic violence, or alcohol abuse compared with those of the nonadopted children. The adoption status was not related to the teacher's report of attention problems, externalizing or internalizing behaviors, after controlling for confounders. Despite less favorable socioeconomic circumstances, a higher extent of behavioral problems was not seen at school age in Inuit children adopted at birth by a family member. Psychosocial stressors associated with adoption are more likely to be responsible for an association with higher levels of childhood behavior problems rather than adoption per se. PMID:25985112

  15. Biological sources of inflexibility in brain and behavior with aging and neurodegenerative diseases

    PubMed Central

    Hong, S. Lee; Rebec, George V.

    2012-01-01

    Almost unequivocally, aging and neurodegeneration lead to deficits in neural information processing. These declines are marked by increased neural noise that is associated with increased variability or inconsistency in behavioral patterns. While it is often viewed that these problems arise from dysregulation of dopamine (DA), a monoamine modulator, glutamate (GLU), an excitatory amino acid that interacts with DA, also plays a role in determining the level of neural noise. We review literature demonstrating that neural noise is highest at both high and low levels of DA and GLU, allowing their interaction to form a many-to-one solution map for neural noise modulation. With aging and neurodegeneration, the range over which DA and GLU can be modulated is decreased leading to inflexibility in brain activity and behavior. As the capacity to modulate neural noise is restricted, the ability to shift noise from one brain region to another is reduced, leading to greater uniformity in signal-to-noise ratios across the entire brain. A negative consequence at the level of behavior is inflexibility that reduces the ability to: (1) switch from one behavior to another; and (2) stabilize a behavioral pattern against external perturbations. In this paper, we develop a theoretical framework where inflexibility across brain and behavior, rather than inconsistency and variability is the more important problem in aging and neurodegeneration. This theoretical framework of inflexibility in aging and neurodegeneration leads to the hypotheses that: (1) dysfunction in either or both of the DA and GLU systems restricts the ability to modulate neural noise; and (2) levels of neural noise and variability in brain activation will be dedifferentiated and more evenly distributed across the brain; and (3) changes in neural noise and behavioral variability in response to different task demands and changes in the environment will be reduced. PMID:23226117

  16. Cyclic Deformation Behavior of Aged FeNiCoAlTa Single Crystals

    NASA Astrophysics Data System (ADS)

    Krooß, P.; Niendorf, T.; Karaman, I.; Chumlyakov, Y.; Maier, H. J.

    2012-11-01

    The cyclic deformation behavior of [001] oriented Fe-28Ni-17Co-11.5Al-2.5Ta (at.%) shape memory single crystals was investigated under tension. Dog-bone shaped specimens were tested up to 100 cycles after different aging heat treatments in order to characterize the cyclic stress-strain response and functional degradation. The smaller particles formed as a consequence of short aging for 1 h at 700°C, as compared to longer aging for 7 h, resulted in significantly enhanced resistance to cyclic degradation.

  17. Analysis of the Parameters Influencing the Quench-Aging Behavior of Ultra-Low-Carbon Steels

    NASA Astrophysics Data System (ADS)

    Massardier, V.; Merlin, J.

    2009-05-01

    The influence of the annealing temperature and of the grain size on the quench-aging behavior of ultra-low-carbon (ULC) steels was investigated by thermoelectric power measurements (TEPs) and mechanical testing. The TEP technique showed that the quench aging of ULC steels occurs in two distinct stages: (1) the segregation of carbon atoms to the grain boundaries and (2) the precipitation of iron carbides. It was suggested that the degree of grain boundary coverage by the carbon atoms resulting from the annealing or aging conditions influences the development of the yield point of ULC steels.

  18. Altered behavioral aspects of aged mice lacking the cellular prion protein.

    PubMed

    Massimino, Maria Lina; Redaelli, Marco; Bertoli, Alessandro; Sorgato, Maria Catia; Mucignat-Caretta, Carla

    2013-07-01

    The biological function of the prion protein, which is intimately involved in the onset of prion diseases, remains unclear. To understand whether the prion protein could play a role in animal behavior, a battery of tests was applied to young and aged mice that express, or not, the prion protein. In contrast to the similar results obtained in all young animals, we found that aged mice lacking the prion protein reacted to new and stressful environments differently than their wild-type counterparts. This may suggest that, upon aging, the absence of the prion protein results in altered neural processing at the basis of adaptation to new situations. PMID:23770331

  19. Improved hardening theory for cyclic plasticity.

    NASA Technical Reports Server (NTRS)

    Vos, R. G.; Armstrong, W. H.

    1973-01-01

    A temperature-dependent version of a combined hardening theory, including isotropic and kinematic hardening, is presented within the framework of recent plasticity formulations. This theory has been found to be especially useful in finite-element analysis of aerospace vehicle engines under conditions of large plastic strain and low-cycle fatigue.

  20. Exogenous Testosterone, Aging, and Changes in Behavioral Response of Gonadally Intact Male Mice

    PubMed Central

    Onaolapo, Olakunle J.; Onaolapo, Adejoke Y.; Omololu, Tope A.; Oludimu, Adedunke T.; Segun-Busari, Toluwalase; Omoleke, Taofeeq

    2016-01-01

    This study tested the hypothesis that aging significantly affects the influence of exogenous testosterone on neurobehavior in gonadally intact male mice. Groups of prepubertal and aged male mice received daily vehicle or testosterone propionate (TP; 2.5 or 5.0 mg/kg intraperitoneal [i.p.]) for 21 days. Behaviors were assessed on days 1 and 21. Weight gain was significant in prepubertal mice. Locomotion and rearing increased in prepubertal mice after first dose and decreased after last dose of TP. Rearing was suppressed in aged mice throughout. Suppression of grooming occurred in both age groups at day 21. Significant increase in working memory in both age groups was seen in the radial-arm maze (at specific doses) and in prepubertal mice in the Y-maze. Elevated plus maze test showed mixed anxiolytic/anxiogenic effects. Aged mice had higher serum testosterone. In conclusion, age is an important determinant for the influence of exogenous testosterone on behavior in gonadally intact male mice. PMID:27158222

  1. Age-Related Differences in Judgments of Inappropriate Behavior are Related to Humor Style Preferences

    PubMed Central

    Stanley, Jennifer Tehan; Lohani, Monika; Isaacowitz, Derek M.

    2014-01-01

    Identifying social gaffes is important for maintaining relationships. Older adults are less able than young to discriminate between socially appropriate and inappropriate behavior in video clips. One open question is how these social appropriateness ratings relate to potential age differences in the perception of what is actually funny or not. In the present study, young, middle-aged, and older adults were equally able to discriminate between appropriate and inappropriate social behavior in a diverse set of clips relevant to both age groups. However, young and middle-aged adults rated the gaffe clips as funnier than control clips and young adults smiled more during the inappropriate clips than the control clips. Older adults did not show this pattern, suggesting that they did not find the inappropriate clips funny. Additionally, young adults endorsed a more aggressive humor style than middle-aged and older adults and aggressive humor style endorsement mediated age differences in social appropriateness ratings. Results are discussed in terms of possible mechanisms such as cohort differences in humor and developmental prioritization of certain humor styles, as well as the importance of investigating age differences in both abilities and preferences. PMID:25244473

  2. Characterization of Aging Behavior in M250 Grade Maraging Steel Using Ultrasonic Measurements

    NASA Astrophysics Data System (ADS)

    Rajkumar, K. V.; Kumar, Anish; Jayakumar, T.; Raj, Baldev; Ray, K. K.

    2007-02-01

    Ultrasonic measurements have been carried out in M250 grade maraging steel specimens subjected to solution annealing at 1093 K for 1 hour followed by aging at 755 K for various durations in the range of 0.25 to 100 hours. The influence of aging on microstructure, room temperature hardness, and ultrasonic parameters (longitudinal and shear wave velocities and Poisson’s ratio) has been studied in order to derive correlations among these parameters in aged M250 maraging steel. Both hardness and ultrasonic velocities exhibit almost similar behaviors with aging time. They increase with the precipitation of intermetallic phases, Ni3Ti and Fe2Mo, and decrease with the reversion of martensite to austenite. Ultrasonic shear wave velocity is found to be more influenced by the precipitation of intermetallic phases, whereas longitudinal wave velocity is influenced more by the reversion of martensite to austenite. Unlike hardness and ultrasonic velocities, the Poisson’s ratio exhibits a monotonous decrease with aging time and, hence, can be used for unambiguous monitoring of the aging process in M250 maraging steel. Further, none of the parameters, i.e., hardness, ultrasonic velocity, or Poisson’s ratio, alone could identify the initiation of the reversion of austenite at early stage; however, the same could be identified from the correlation between ultrasonic velocity and Poisson’s ratio, indicating the advantage of using the multiparametric approach for comprehensive characterization of complex aging behavior in M250 grade maraging steel.

  3. Age-dependent change in behavioral feature in Rubinstein-Taybi syndrome.

    PubMed

    Yagihashi, Tatsuhiko; Kosaki, Kenjiro; Okamoto, Nobuhiko; Mizuno, Seiji; Kurosawa, Kenji; Takahashi, Takao; Sato, Yuji; Kosaki, Rika

    2012-06-01

    Rubinstein-Taybi syndrome (RTS) is characterized by developmental delay, postnatal growth retardation, typical facial appearance, and broad thumbs and big toes. The behavioral phenotype of children with RTS has been described as friendly and having good social contacts; however, a short attention span and hyperactivity are sometimes present. Little attention has been paid to the behavioral aspects of adults with RTS. We conducted an observational study focusing on behavioral problems in adolescents and adults with RTS compared with children with RTS. A total of 63 patients with RTS and their caretakers answered self-administered questionnaires regarding behavioral features including the Child Behavior Checklist (CBCL). High total CBCL scores were observed, and the mean score was beyond the clinical cut-off point. After stratification into two groups according to age, the older group (≥14 years) displayed statistically significant higher scores for Anxious/Depression (P = 0.002) and Aggressive Behavior (P = 0.036) than the younger group (≤13 years). In analyses of single items, statistically significant differences between the younger group and the older group were found for 'Nervous, high-strung, or tense' (31.3% vs 67.7%, P = 0.004) and 'Too fearful or anxious' (37.5% vs 64.5%, P = 0.032). Here, we showed that the specific behavioral phenotypes of RTS change during adolescence, with anxiety, mood instability, and aggressive behavior emerging as patients age. A clear need exists to follow-up patients with RTS to catch the eventual emergence of psychiatric problems with age. If necessary, pharmacological treatment should be considered. PMID:22639993

  4. Parental Loss and Eating-Related Cognitions and Behaviors in College-Age Women

    ERIC Educational Resources Information Center

    Beam, Minna R.; Servaty-Seib, Heather L.; Mathews, Laura

    2004-01-01

    To examine the eating-related cognitions and behaviors of college-age women who had experienced parental death, parental divorce, or neither loss condition, we recruited 48 women from science and social science departments at a state university in the Southeast. All participants completed the Mizes Anorectic Cognitions Scale (MAC) and the Bulimia…

  5. Progress in Research on Aging in the Behavioral and Social Sciences.

    ERIC Educational Resources Information Center

    Birren, James E.

    1980-01-01

    Proposes a biobehavioral view of research on aging which suggests that behavior depends upon the limits set by genetic heritage, the modifications and reinforcements of physical and social environments, and the self-concept achieved through the integration of past life experiences. (Author/SS)

  6. Maternal Age at Childbirth and Offspring Disruptive Behaviors: Testing the Causal Hypothesis

    ERIC Educational Resources Information Center

    D'Onofrio, Brian M.; Goodnight, Jackson A.; Van Hulle, Carol A.; Rodgers, Joseph Lee; Rathouz, Paul J.; Waldman, Irwin D.; Lahey, Benjamin B.

    2009-01-01

    Background: Recent studies suggest that the association between maternal age at childbearing (MAC) and children's disruptive behaviors is the result of family factors that are confounded with both variables, rather than a casual effect of environmental factors specifically related to MAC. These studies, however, relied on restricted samples and…

  7. Effects of Age on the Adaptive Behavior of Institutionalized and Noninstitutionalized Individuals with Down Syndrome.

    ERIC Educational Resources Information Center

    Silverstein, A. B.; And Others

    1988-01-01

    Evidence of an association between Alzheimer disease and Down syndrome led to three studies on the effects of age on the adaptive behavior of over 400 Down syndrome individuals. One study found a decline in motor development competence among older (over 60 years) Down syndrome individuals when compared with other mentally retarded persons.…

  8. Resolving Issues Relevant to the Education of Secondary School Aged Youth with Behavior Disorders.

    ERIC Educational Resources Information Center

    Simpson, Robert G.

    The article provides a format for a workshop in which three issues which must be resolved by educators of secondary aged students with behavior disorders are discussed. The three issues to be addressed are: (1) determination of appropriate curriculum emphasis, (2) parent training/involvement in intervention strategies, and (3) criteria for…

  9. Neurocognitive and Behavioral Outcomes of Younger Siblings of Children with Autism Spectrum Disorder at Age Five

    ERIC Educational Resources Information Center

    Warren, Zachary E.; Foss-Feig, Jennifer H.; Malesa, Elizabeth E.; Lee, Evon Batey; Taylor, Julie Lounds; Newsom, Cassandra R.; Crittendon, Julie; Stone, Wendy L.

    2012-01-01

    Later-born siblings of children with Autism Spectrum Disorders (ASD) are at increased risk for ASD as well as qualitatively similar traits not meeting clinical cutoffs for the disorder. This study examined age five neurocognitive and behavioral outcomes of 39 younger siblings of children with ASD (Sibs-ASD) and 22 younger siblings of typically…

  10. Differences in cooperative behavior among Damaraland mole rats are consequences of an age-related polyethism.

    PubMed

    Zöttl, Markus; Vullioud, Philippe; Mendonça, Rute; Torrents Ticó, Miquel; Gaynor, David; Mitchell, Adam; Clutton-Brock, Tim

    2016-09-13

    In many cooperative breeders, the contributions of helpers to cooperative activities change with age, resulting in age-related polyethisms. In contrast, some studies of social mole rats (including naked mole rats, Heterocephalus glaber, and Damaraland mole rats, Fukomys damarensis) suggest that individual differences in cooperative behavior are the result of divergent developmental pathways, leading to discrete and permanent functional categories of helpers that resemble the caste systems found in eusocial insects. Here we show that, in Damaraland mole rats, individual contributions to cooperative behavior increase with age and are higher in fast-growing individuals. Individual contributions to different cooperative tasks are intercorrelated and repeatability of cooperative behavior is similar to that found in other cooperatively breeding vertebrates. Our data provide no evidence that nonreproductive individuals show divergent developmental pathways or specialize in particular tasks. Instead of representing a caste system, variation in the behavior of nonreproductive individuals in Damaraland mole rats closely resembles that found in other cooperatively breeding mammals and appears to be a consequence of age-related polyethism. PMID:27588902

  11. Cognitive and Behavioral Indicators of ADHD Symptoms Prior to School Age

    ERIC Educational Resources Information Center

    Arnett, Anne Bernard; MacDonald, Beatriz; Pennington, Bruce F.

    2013-01-01

    Background: Previous research on the etiology of ADHD symptoms suggests that neuropsychological differences may be present as early as birth; however, the diagnosis is typically not given until school age. This study aimed to (a) identify early behavioral and cognitive markers of later significant parent and/or teacher ratings of ADHD…

  12. Sex Differences in Persistence Behavior of Children Ages 11-13.

    ERIC Educational Resources Information Center

    Campbell, Stephen N.; Henry, Rolando

    The relationship of boys' and girls' level of aspiration (LOA), achievement motivation, manifest anxiety, and intelligence to persistence behavior was explored in this study. Forty boys and 40 girls (ages 11-13) from two Catholic schools participated in this study. To measure subjects' persistence and LOA, subjects were given 5 sets of puzzle…

  13. Children's Judgments of Social Interactive Behaviors with Peers: The Influence of Age and Gender

    ERIC Educational Resources Information Center

    Tisak, Marie S.; Tisak, John; Laurene, Kimberly R.

    2012-01-01

    Participants (138 children; 7-12 years of age) rated how often nice and not nice behaviors occurred when (a) participants (boys/girls) were the actor and peers (males/females) were the target and (b) when participants were the target of peers' actions in a school setting. Children indicated they were nicer to their same-gender peers than to their…

  14. Kinematic hardening of a porous limestone

    NASA Astrophysics Data System (ADS)

    Cheatham, J. B.; Allen, M. B.; Celle, C. C.

    1984-10-01

    A concept for a kinematic hardening yield surface in stress space for Cordova Cream limestone (Austin Chalk) developed by Celle and Cheatham (1981) has been improved using Ziegler's modification of Prager's hardening rule (Ziegler, 1959). Data to date agree with the formulated concepts. It is shown how kinematic hardening can be used to approximate the yield surface for a wide range of stress states past the initial yield surface. The particular difficulty of identifying the yield surface under conditions of unloading or extension is noted. A yield condition and hardening rule which account for the strain induced anisotropy in Cordova Cream Limestone were developed. Although the actual yield surface appears to involve some change of size and shape, it is concluded that true kinematic hardening provides a basis for engineering calculations.

  15. Challenges in hardening technologies using shallow-trench isolation

    SciTech Connect

    Shaneyfelt, M.R.; Dodd, P.E.; Draper, B.L.; Flores, R.S.

    1998-02-01

    Challenges related to radiation hardening CMOS technologies with shallow-trench isolation are explored. Results show that trench hardening can be more difficult than simply replacing the trench isolation oxide with a hardened field oxide.

  16. Cognitive and Behavioral Indicators of ADHD Symptoms Prior to School Age

    PubMed Central

    Arnett, Anne Bernard; MacDonald, Beatriz; Pennington, Bruce F.

    2013-01-01

    Background Previous research on the etiology of ADHD symptoms suggests that neuropsychological differences may be present as early as birth; however, the diagnosis is typically not given until school age. The current study aimed to 1) identify early behavioral and cognitive markers of later significant parent and/or teacher ratings of ADHD symptomology, 2) examine sex differences in these predictors, and 3) describe the developmental trajectories of comorbid symptoms in school aged children. Methods 1,106 children and at least one parent enrolled in the NICHD Study of Early Child Care and Youth Development were followed from 1 month of age through 6th grade. Effect size calculations, discriminant function analysis, and growth curve analyses were conducted to address the three aims. Results Children with high- versus low-ADHD symptomology at 3rd grade could be distinguished using cognitive and behavioral measures as early as 15 months (females) and 24 months (males). Sensitivity and specificity were modest at 15, 24 and 26 months. Growth curves revealed significant differences between high- and low-ADHD groups in comorbid symptoms at Kindergarten, and significantly different slopes for externalizing, social skills and academic skills ratings across elementary school. There were few gender differences on cognitive and behavioral variables within the high-ADHD group. Conclusions Cognitive and behavioral markers of ADHD symptoms are present in children prior to entry into formal schooling, but current behavioral screeners are not developmentally sensitive to these differences in infancy and toddlerhood. PMID:23848372

  17. A mathematical model to predict the strength of aluminum alloys subjected to precipitation hardening

    SciTech Connect

    Qureshi, F.S.; Sheikh, A.K.; Rashid, M.

    1999-06-01

    A number of alloys, notably most of the aluminum alloys, can be heat treated by aging. This aging due to time-dependent precipitation hardening increases the strength and hardness as well as modifying other mechanical properties. Precipitation hardening has been a popular strengthening mechanism for many decades; therefore, extensive information is available in literature about the precipitation-hardening response of various series of aluminum alloys. The age-hardening response of these alloys is usually represented in graphical form as plotted between property changes and aging time for different temperatures. In designing a suitable precipitation-hardening strategy, one can refer to these graphs. However, for automatic control of aging furnaces, as well as for decision making regarding optimal selection of aging conditions (time/temperature combination), it is desirable to express these relationships in a formal mathematical structure. A mathematical model is developed in this article for widely used heat treatable aluminum alloys used in the extrusion industry. This model is a condensed representation of all {sigma} = f(T,t) curves in different series of aluminum alloys, and the parameters of this model characterize the various compositions of the alloys in the series.

  18. Genotype by Sex and Genotype by Age Interactions with Sedentary Behavior: The Portuguese Healthy Family Study

    PubMed Central

    Santos, Daniel M. V.; Katzmarzyk, Peter T.; Diego, Vincent P.; Blangero, John; Souza, Michele C.; Freitas, Duarte L.; Chaves, Raquel N.; Gomes, Thayse N.; Santos, Fernanda K.; Maia, José A. R.

    2014-01-01

    Sedentary behavior (SB) expression and its underlying causal factors have been progressively studied, as it is a major determinant of decreased health quality. In the present study we applied Genotype x Age (GxAge) and Genotype x Sex (GxSex) interaction methods to determine if the phenotypic expression of different SB traits is influenced by an interaction between genetic architecture and both age and sex. A total of 1345 subjects, comprising 249 fathers, 327 mothers, 334 sons and 325 daughters, from 339 families of The Portuguese Healthy Family Study were included in the analysis. SB traits were assessed by means of a 3-d physical activity recall, the Baecke and IPAQ questionnaires. GxAge and GxSex interactions were analyzed using SOLAR 4.0 software. Sedentary behaviour heritability estimates were not always statistically significant (p>0.05) and ranged from 3% to 27%. The GxSex and GxAge interaction models were significantly better than the single polygenic models for TV (min/day), EEsed (kcal/day), personal computer (PC) usage and physical activty (PA) tertiles. The GxAge model is also significantly better than the polygenic model for Sed (min/day). For EEsed, PA tertiles, PC and Sed, the GxAge interaction was significant because the genetic correlation between SB environments was significantly different from 1. Further, PC and Sed variance heterogeneity among distinct ages were observed. The GxSex interaction was significant for EEsed due to genetic variance heterogeneity between genders and for PC due to a genetic correlation less than 1 across both sexes. Our results suggest that SB expression may be influenced by the interactions between genotype with both sex and age. Further, different sedentary behaviors seem to have distinct genetic architectures and are differentially affected by age and sex. PMID:25302714

  19. Association of Eating Behavior With Nutritional Status and Body Composition in Primary School-Aged Children.

    PubMed

    Tay, Chee Wee; Chin, Yit Siew; Lee, Shoo Thien; Khouw, Ilse; Poh, Bee Koon

    2016-07-01

    Problematic eating behaviors during childhood may lead to positive energy balance and obesity. Therefore, this study aims to investigate the association of eating behaviors with nutritional status and body composition in Malaysian children aged 7 to 12 years. A total of 1782 primary schoolchildren were randomly recruited from 6 regions in Malaysia. The multidimensional Children's Eating Behaviour Questionnaire (CEBQ) was reported by parents to determine the 8 different dimensions of eating styles among children. Body mass index (BMI), BMI-for-age Z-score, waist circumference, and body fat percentage were assessed. Linear regression analyses revealed that both food responsiveness and desire to drink subscales were positively associated with a child's body adiposity, whereas satiety responsiveness, slowness in eating, and emotional undereating subscales were negatively associated with adiposity (all P < .05). A multidimensional eating style approach based on the CEBQ is needed to promote healthy eating behaviors in order to prevent excessive weight gain and obesity problems among Malaysian children. PMID:27252248

  20. Links between Children's Attachment Behavior at Early School-Age, Their Attachment-Related Representations, and Behavior Problems in Middle Childhood

    ERIC Educational Resources Information Center

    Moss, Ellen; Bureau, Jean-Francois; Beliveau, Marie-Julie; Zdebik, Magdalena; Lepine, Suzanne

    2009-01-01

    The objective of the present study was to examine associations between children's attachment behavior at early school-age, dimensions of narrative performance, and behavior problems as assessed in middle childhood. Children's attachment patterns with mother were assessed at age 6 (N = 127) using the Main and Cassidy (1988) separation--reunion…

  1. CMOS inverter design-hardened to the total dose effect

    SciTech Connect

    Roche, F.M.; Salager, L.

    1996-12-01

    This paper reports and discusses the experimental behavior of two inverter structures Rad-Hardened by Design to {sup 60}Co irradiation. The authors use the results on a set of basic circuits and transistors exposed to the same total doses as these structures to establish the effective formation conditions of the parasitic channel. Then this leakage evolution is related to the gate voltage history under irradiation. Finally, they take advantage of this intrinsic degradation property to propose a new Design Rad Hardened (DRH) cell. This structure considerably limits the Low Noise Margin degradation, helps to maintain the logic functionality with a High Output level and improves both the rad-tolerance and the static power consumption.

  2. Longitudinal Relations Between Observed Parenting Behaviors and Dietary Quality of Meals From Ages 2 to 5

    PubMed Central

    Montaño, Zorash; Smith, Justin D.; Dishion, Thomas J.; Shaw, Daniel S.; Wilson, Melvin N.

    2015-01-01

    Objectives Parents influence a child’s diet by modeling food choices, selecting the food they will make available, and controlling the child’s intake. Few studies have examined the covariation between parent’s behavior management practices and their guidance and support for a young child’s nutritional environment in early childhood. We hypothesized that parents’ positive behavior support (PBS), characterized as skillful behavior management and proactive structuring of children’s activities, would predict dietary quality over the course of early childhood (age 2 to 5 years), a critical period for the development of a dietary lifestyle through the lifespan. Methods Participants included 731 culturally diverse, low-income families in a randomized, controlled trial of the Family Check-Up. Families participated in a yearly home visit videotaped assessment when children were 2 to 5 years. PBS and dietary quality of meals parents served to their children were assessed by coding videotapes of structured parent–child interactions, including a meal preparation task. A cross-lagged panel model was used to evaluate the longitudinal relation between PBS and the dietary quality of meals served during the meal preparation task. Results Analyses revealed that PBS repeatedly predicted meals’ dietary quality the following year: age 2–3 (β = .30), age 3–4 (β = 0.14), age 4–5 (β = 0.37). Dietary quality significantly predicted PBS 1 year later: age 3–4 (β = 0.16), age 4–5 (β = 0.14). As expected, the relative strength of the relationship from PBS to dietary quality was significantly stronger than the reverse, from dietary quality to PBS. Conclusions Positive behavior management and proactive parenting practices are an important foundation for establishing a healthy nutritional environment for young children. These findings suggest that family-centered prevention interventions for pediatric obesity may benefit from targeting PBS in service of promoting

  3. In Vivo Glutamate Measured with MR Spectroscopy: Behavioral Correlates in Aging

    PubMed Central

    Zahr, Natalie M.; Mayer, Dirk; Rohlfing, Torsten; Chanraud, Sandra; Gu, Meng; Pfefferbaum, Adolf

    2012-01-01

    Summary Altered availability of the brain biochemical glutamate may contribute to the neural mechanisms underlying age-related changes in cognitive and motor functions. To investigate the contribution of regional glutamate levels to behavior in the aging brain, we used an in vivo Magnetic Resonance Spectroscopy (MRS) protocol optimized for glutamate detection in 3 brain regions targeted by cortical glutamatergic efferents—striatum, cerebellum, and pons. Data from 61 healthy men and women ranging in age from 20 – 86 years were used. Older age was associated with lower glutamate levels in the striatum, but not cerebellum or pons. Older age was also predictive of poorer performance on tests of visuomotor skills and balance. Low striatal glutamate levels were associated with high systolic blood pressure and worse performance on a complex visuomotor task, the Grooved Pegboard. These findings suggest that low brain glutamate levels are related to high blood pressure and that changes in brain glutamate levels might mediate the behavioral changes noted in normal aging. PMID:23116877

  4. Age-related changes in visual exploratory behavior in a natural scene setting

    PubMed Central

    Hamel, Johanna; De Beukelaer, Sophie; Kraft, Antje; Ohl, Sven; Audebert, Heinrich J.; Brandt, Stephan A.

    2013-01-01

    Diverse cognitive functions decline with increasing age, including the ability to process central and peripheral visual information in a laboratory testing situation (useful visual field of view). To investigate whether and how this influences activities of daily life, we studied age-related changes in visual exploratory behavior in a natural scene setting: a driving simulator paradigm of variable complexity was tested in subjects of varying ages with simultaneous eye- and head-movement recordings via a head-mounted camera. Detection and reaction times were also measured by visual fixation and manual reaction. We considered video computer game experience as a possible influence on performance. Data of 73 participants of varying ages were analyzed, driving two different courses. We analyzed the influence of route difficulty level, age, and eccentricity of test stimuli on oculomotor and driving behavior parameters. No significant age effects were found regarding saccadic parameters. In the older subjects head-movements increasingly contributed to gaze amplitude. More demanding courses and more peripheral stimuli locations induced longer reaction times in all age groups. Deterioration of the functionally useful visual field of view with increasing age was not suggested in our study group. However, video game-experienced subjects revealed larger saccade amplitudes and a broader distribution of fixations on the screen. They reacted faster to peripheral objects suggesting the notion of a general detection task rather than perceiving driving as a central task. As the video game-experienced population consisted of younger subjects, our study indicates that effects due to video game experience can easily be misinterpreted as age effects if not accounted for. We therefore view it as essential to consider video game experience in all testing methods using virtual media. PMID:23801970

  5. Model Identification and FE Simulations: Effect of Different Yield Loci and Hardening Laws in Sheet Forming

    NASA Astrophysics Data System (ADS)

    Flores, P.; Duchêne, L.; Lelotte, T.; Bouffioux, C.; El Houdaigui, F.; Van Bael, A.; He, S.; Duflou, J.; Habraken, A. M.

    2005-08-01

    The bi-axial experimental equipment developed by Flores enables to perform Baushinger shear tests and successive or simultaneous simple shear tests and plane-strain tests. Such experiments and classical tensile tests investigate the material behavior in order to identify the yield locus and the hardening models. With tests performed on two steel grades, the methods applied to identify classical yield surfaces such as Hill or Hosford ones as well as isotropic Swift type hardening or kinematic Armstrong-Frederick hardening models are explained. Comparison with the Taylor-Bishop-Hill yield locus is also provided. The effect of both yield locus and hardening model choice will be presented for two applications: Single Point Incremental Forming (SPIF) and a cup deep drawing.

  6. Deformation and strain hardening of different steels in impact dominated systems

    SciTech Connect

    Rojacz, H.; Mozdzen, G.; Winkelmann, H.

    2014-04-01

    Strain hardening is a common technique to exploit the full potential of materials in diverse applications. Single impact studies were performed to evaluate work hardening effects of different steels, correlated to their deformation at different energy and momentum levels. Three different steels were examined regarding their forming behavior and their tendency to strain harden in impact loading conditions, revealing different intensities of hardness increase, deformation and coinciding microstructural changes. Detailed studies in the deformed zone such as micro hardness mappings were performed to reveal the materials hardness increase in the deformed zones. Additionally high resolution scanning electron microscopy (HRSEM) supported by electron backscatter diffraction (EBSD) was used to determine microstructural changes. Results indicate, that the influence of different velocities/strain rates at constant energy levels cannot be neglected for the strain hardening behavior of steels and provide data for a better control of the hardness increase in impact dominated materials fabrication operations. - Highlights: • Deformation and strain hardening behaviour of three different steels. • Influence of impact energies and momenta on the strain hardening. • Hardness increase and depth controllable by momentum and energy.

  7. Assessment of Cheating Behavior in Young School-Age Children: Distinguishing Normative Behaviors From Risk Markers of Externalizing Psychopathology

    PubMed Central

    Callender, Kevin A.; Olson, Sheryl L.; Kerr, David C. R.; Sameroff, Arnold J.

    2014-01-01

    The central goal of this longitudinal study was to develop a laboratory-based index of children’s covert cheating behavior that distinguished normative rule violations from those that signal risk for antisocial behavior. Participants (N = 215 children) were drawn from a community population and oversampled for externalizing behavior problems (EXT). Cheating behavior was measured using two resistance-to-temptation tasks and coded for extent of cheating, latency to cheat, and inappropriate positive affect. Mothers rated internalized conduct and three forms of self-regulation: inhibitory control, impulsivity, and affective distress. Mothers and teachers reported EXT concurrently (T1) and 4 years later, when children averaged 10 years of age (T2). Children categorized as severe cheaters manifested lower inhibitory control, greater impulsivity, and lower levels of internalized conduct at T1. Children in this group also manifested higher levels of EXT in home and school settings at T1 and more EXT in the school setting at T2, even after accounting for T1 ratings. PMID:21058125

  8. Assessment of cheating behavior in young school-age children: distinguishing normative behaviors from risk markers of externalizing psychopathology.

    PubMed

    Callender, Kevin A; Olson, Sheryl L; Kerr, David C R; Sameroff, Arnold J

    2010-01-01

    The central goal of this longitudinal study was to develop a laboratory-based index of children's covert cheating behavior that distinguished normative rule violations from those that signal risk for antisocial behavior. Participants (N = 215 children) were drawn from a community population and oversampled for externalizing behavior problems (EXT). Cheating behavior was measured using two resistance-to-temptation tasks and coded for extent of cheating, latency to cheat, and inappropriate positive affect. Mothers rated internalized conduct and three forms of self-regulation: inhibitory control, impulsivity, and affective distress. Mothers and teachers reported EXT concurrently (T1) and 4 years later, when children averaged 10 years of age (T2). Children categorized as severe cheaters manifested lower inhibitory control, greater impulsivity, and lower levels of internalized conduct at T1. Children in this group also manifested higher levels of EXT in home and school settings at T1 and more EXT in the school setting at T2, even after accounting for T1 ratings. PMID:21058125

  9. Facilitators and Inhibitors of Health-promoting Behaviors: The Experience of Iranian Women of Reproductive Age

    PubMed Central

    Baheiraei, Azam; Mirghafourvand, Mojgan; Charandabi, Sakineh Mohammad-Alizadeh; Mohammadi, Eesa

    2013-01-01

    Background: There is scant information on the facilitators and inhibitors of health-promoting behaviors among reproductive-aged Iranian women. This study aims to explore the experience of factors influencing health-promoting behaviors among Iranian women of reproductive age from a qualitative perspective. Methods: This study was performed in Tehran in 2011, over about 8 months. Qualitative methods, specifically in-depth interviews, were used to gather data on 15 women of reproductive age. Data continued to be collected until introduction of new information ceased. The interviews were recorded, transcribed verbatim, and analyzed by conventional content analysis. Results: The reported factors were categorized into four main groups and 12 subgroups: (1) personal barriers (lack of time, school or work duties, lack of preparation or motivation, physical disability); (2) socio-environmental barriers (family responsibilities, environmental pressures, high-costs and financial pressures); (3) personal facilitators (personal interest and motivation, experience of disease); and (4) socio-environmental facilitators (family and social support networks, encouraging and motivating environment, media, and public education). Conclusions: In these women's experience, factors influencing health-promoting behaviors were either facilitators or inhibitors; most were inhibitors. The findings of this study show that, in addition to personal factors, the pursuit of health-promoting behaviors is affected by socio-environmental factors. These results will be useful in designing interventions and plans for women's health promotion that focus on the improvement of their environment and the modification of social factors. PMID:24049620

  10. Effect of Aging on the Fracture Behavior of Lean Duplex Stainless Steels

    NASA Astrophysics Data System (ADS)

    Straffelini, G.; Baldo, S.; Calliari, I.; Ramous, E.

    2009-11-01

    The influence of aging in the range of 550 °C to 850 °C for 5 to 120 minutes on the impact fracture behavior of 2101 and 2304 lean duplex stainless steels (DSS) was investigated in the present study. The 2304 steel displayed ductile behavior irrespective of aging conditions. In contrast, the 2101 steel displayed a ductile behavior only in the case of aging for 5 minutes at 550 °C and 650 °C, whereas in all other cases, it fractured in a brittle manner. The brittle fracture behavior of the 2101 steel has been attributed to the precipitation of small black particles at the α/ α and α/ γ grain boundaries (nitrides), which form paths for easy crack propagation. In the 2304 steel, such particles precipitated at 750 °C and 850 °C, but they were located inside the austenitic grains because of the formation of secondary austenite. They therefore did not embrittle the steel. The larger Ni content of the 2304 steel favored the formation of the secondary austenite that is absent in the 2101 steel.

  11. Aging and loading rate effects on the mechanical behavior of equine bone

    NASA Astrophysics Data System (ADS)

    Kulin, Robb M.; Jiang, Fengchun; Vecchio, Kenneth S.

    2008-06-01

    Whether due to a sporting accident, high-speed impact, fall, or other catastrophic event, the majority of clinical bone fractures occur under dynamic loading conditions. However, although extensive research has been performed on the quasi-static fracture and mechanical behavior of bone to date, few high-quality studies on the fracture behavior of bone at high strain rates have been performed. Therefore, many questions remain regarding the material behavior, including not only the loading-rate-dependent response of bone, but also how this response varies with age. In this study, tests were performed on equine femoral bone taken post-mortem from donors 6 months to 28 years of age. Quasi-static and dynamic tests were performed to determine the fracture toughness and compressive mechanical behavior as a function of age at varying loading rates. Fracture paths were then analyzed using scanning confocal and scanning-electron microscopy techniques to assess the role of various microstructural features on toughening mechanisms.

  12. Extracting material response from simple mechanical tests on hardening-softening-hardening viscoplastic solids

    NASA Astrophysics Data System (ADS)

    Mohan, Nisha

    Uniaxial Compression of Vertically Aligned Carbon Nanotubes," J. Mech.Phys. Solids, 59, pp. 2227--2237, Erratum 60, 1753-1756 (2012)], the property space exploration was advanced to three types of simple mechanical tests: 1) uniaxial compression, 2) uniaxial tension, and 3) nanoindentation with a conical and a flat-punch tip. The simulations attempt to explain some of the salient features in experimental data, like 1) The initial linear elastic response. 2) One or more nonlinear instabilities, yielding, and hardening. The model-inherent relationships between the material properties and the overall stress-strain behavior were validated against the available experimental data. The material properties include the gradient in stiffness along the height, plastic and elastic compressibility, and hardening. Each of these tests was evaluated in terms of their efficiency in extracting material properties. The uniaxial simulation results proved to be a combination of structural and material influences. Out of all deformation paths, flat-punch indentation proved to be superior since it is the most sensitive in capturing the material properties.

  13. Synergistic Effects of Physical Aging and Damage on Long-Term Behavior of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Brinson, L. Cate

    1999-01-01

    The research consisted of two major parts, first modeling and simulation of the combined effects of aging and damage on polymer composites and secondly an experimental phase examining composite response at elevated temperatures, again activating both aging and damage. For the simulation, a damage model for polymeric composite laminates operating at elevated temperatures was developed. Viscoelastic behavior of the material is accounted for via the correspondence principle and a variational approach is adopted to compute the temporal stresses within the laminate. Also, the effect of physical aging on ply level stress and on overall laminate behavior is included. An important feature of the model is that damage evolution predictions for viscoelastic laminates can be made. This allows us to track the mechanical response of the laminate up to large load levels though within the confines of linear viscoelastic constitutive behavior. An experimental investigation of microcracking and physical aging effects in polymer matrix composites was also pursued. The goal of the study was to assess the impact of aging on damage accumulation, in ten-ns of microcracking, and the impact of damage on aging and viscoelastic behavior. The testing was performed both at room and elevated temperatures on [+/- 45/903](sub s) and [02/903](sub s) laminates, both containing a set of 90 deg plies centrally located to facilitate investigation of microcracking. Edge replication and X-ray-radiography were utilized to quantify damage. Sequenced creep tests were performed to characterize viscoelastic and aging parameters. Results indicate that while the aging times studied have limited ]Influence on damage evolution, elevated temperature and viscoelastic effects have a profound effect on the damage mode seen. Some results are counterintuitive, including the lower strain to failure for elevated temperature tests and the catastrophic failure mode observed for the [+/- 45/9O3](sub s), specimens. The

  14. The relationship of brain structure to age and executive functioning in adolescent disruptive behavior disorder.

    PubMed

    Hummer, Tom A; Wang, Yang; Kronenberger, William G; Dunn, David W; Mathews, Vincent P

    2015-03-30

    Characterizing brain maturation in adolescents with disruptive behavior disorders (DBDs) may provide insight into the progression of their behavioral deficits. Therefore, this study examined how age and executive functioning were related to structural neural characteristics in DBD. Thirty-three individuals (aged 13-17) with a DBD, along with a matched control sample, completed neuropsychological testing and underwent magnetic resonance imaging (MRI) to measure gray matter volume and microstructural white matter properties. Voxel-based morphometry quantified gray matter volume, and diffusion tensor imaging measured fractional anisotropy (FA) in white matter tracts. In the anterior cingulate, gray matter volume decreased with age in healthy controls but showed no such change in the DBD sample. In the corpus callosum and superior longitudinal fasciculus (SLF), FA increased with age in the control sample significantly more than in the DBD sample. Executive functioning, particularly working memory, was associated with SLF FA bilaterally. However, the relationship of SLF FA to working memory performance was weaker in the DBD sample. These data suggest that youth with DBD have altered brain development compared with typically developing youth. The abnormal maturation of the anterior cingulate and frontoparietal tracts during adolescence may contribute to the persistence of behavioral deficits in teens with a DBD. PMID:25533028

  15. Study on the Aging Behaviors of Rubber Materials in Tension and Compression Loads

    NASA Astrophysics Data System (ADS)

    Jiang, Can; Wang, Hongyu; Ma, Xiaobing

    Rubber materials are widely used in aviation, aerospace, shipbuilding, automobile and other military field. However, rubber materials are easy to aging, which largely restricts its using life. In working environment, due to the combined effect of heat and oxygen, vulcanized rubber will undergo degradation and crosslinking reaction which will cause elasticity decease and permanent deformation, so mostly rubber products are used under stress state. Due to the asymmetric structure and asymmetric stress distribution, mechanical stress may cause serious damage to molecular structure; therefore, this paper is aimed to analyze the aging behavior of rubber materials under tensile and compressive loadings, through analyzing experiment data, and adopting Gauss function to describe stress relaxation coefficient, to build an aging equation containing compression ratio parameter and aging time.

  16. Directionality Between Tolerance of Deviance and Deviant Behavior is Age-Moderated in Chronically Stressed Youth

    PubMed Central

    Ridenour, TY A.; Caldwell, Linda L.; Coatsworth, J. Douglas; Gold, Melanie A.

    2011-01-01

    Problem behavior theory posits that tolerance of deviance is an antecedent to antisocial behavior and substance use. In contrast, cognitive dissonance theory implies that acceptability of a behavior may increase after experiencing the behavior. Using structural equation modeling, this investigation tested whether changes in tolerance of deviance precede changes in conduct disorder criteria or substance use or vice versa, or if they change concomitantly. Two-year longitudinal data from 246 8- to 16-year-olds suggested that tolerance of deviance increases after conduct disorder criteria or substance use in 8-to-10- and 11-to-12-year-olds. These results were consistent with cognitive dissonance theory. In 13-to-16- year-olds, no directionality was suggested, consistent with neither theory. These results were replicated in boys and girls and for different types of conduct disorder criteria aggression (covert behavior), deceitfulness and vandalism (overt behavior), and serious rule-breaking (authority conflict). The age-specific directionality between tolerance of deviance and conduct disorder criteria or substance use is consistent with unique etiologies between early onset versus adolescent-onset subtypes of behavior problems. PMID:22180721

  17. Cyclic hardening mechanisms in Nimonic 80A

    NASA Technical Reports Server (NTRS)

    Lerch, B. A.; Gerold, V.

    1987-01-01

    A nickel base superalloy was fatigued under constant plastic strain range control. The hardening response was investigated as a function of plastic strain range and particle size of the gamma prime phase. Hardening was found to be a function of the slip band spacing. Numerous measurements of the slip band spacing and other statistical data on the slip band structures were obtained. Interactions between intersecting slip systems were shown to influence hardening. A Petch-Hall model was found to describe best this relationship between the response stress and the slip band spacing.

  18. PROGRESSIVE MECHANICAL BEHAVIOR OF HUMAN CORTICAL BONE IN TENSION FOR TWO AGE GROUPS

    PubMed Central

    Nyman, Jeffry S.; Roy, Anuradha; Reyes, Michael J.; Wang, Xiaodu

    2007-01-01

    The capacity of bone for post-yield energy dissipation decreases with age. To gain information on the cause of such changes, we examined the mechanical behavior of human cadaveric bone as a function of progressive deformation. In this study, tensile specimens from tibiae of 9 middle aged and 8 elderly donors were loaded till failure in an incremental and cyclic (load-dwell-unload-dwell-reload) scheme. The elastic modulus, maximum stress, permanent strain, stress relaxation, viscoelastic time constant, plastic strain energy, elastic release strain energy, and hysteresis energy were determined at incremental strains of each loading cycle. Experimental results showed that elderly bone failed at much lower strains compared to middle aged bone, but little age-related differences were observed in the mechanical behavior of bone until the premature failure of elderly bone. Energy dissipation and permanent strain appeared to linearly increase with increasing strain, while non-linear changes occurred in the modulus loss and stress relaxation/time constant with increasing strain. Such changes suggest that two distinct stages may exist in the progressive deformation of bone. In Stage I, rapid damage accumulation and increased involvement of collagen in load bearing appeared to dominate the mechanical behavior of bone with limited energy dissipation (<20% of total energy dissipated), whereas Stage II is dominated by continuous plastic deformation, accompanied by major energy dissipation through all three pathways till failure. This study suggests that damaging mechanisms in bone vary with deformation and age affects the post-yield mechanisms causing a significant decline in the capacity of aged bone to dissipate energy. PMID:18437693

  19. Interaction Between Age and Exposure to 56Fe Particles on Behavior and Neurochemistry

    NASA Astrophysics Data System (ADS)

    Shukitt-Hale, B.; Carey, A. N.; Rabin, B. M.; Joseph, J. A.

    Previous research has shown that exposure to HZE particles and protons which will be encountered on long-term space missions can adversely affect the ability of rats to perform a variety of behavioral tasks This outcome has implications for an astronaut s ability to successfully complete requirements associated with these missions It has also been found that irradiation can lead to increases in oxidative stress similar to that seen in the aging brain Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles Therefore we exposed young and old rats to either 1 or 2Gy of 56 Fe irradiation and evaluated performance in a spatial learning and memory task in addition to examining levels of dopamine DA release from superfused striatal slices Results indicated that exposure to 56 Fe particles can produce alterations in behavior and signaling and that these alterations may be more apparent in older organisms which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance Therefore age may be a factor for consideration in planning long-term missions into space Supported by NASA Grants NAG9-1190 and NAG9-1529

  20. Interaction between age and exposure to 56Fe particles on behavior and neurochemistry

    NASA Astrophysics Data System (ADS)

    Carey, Amanda N.; Shukitt-Hale, Barbara; Rabin, Bernard M.; Joseph, James A.

    Previous research has shown that exposure to HZE particles, which will be encountered on long-term space missions, can adversely affect the ability of rats to perform a variety of behavioral tasks. This outcome has implications for an astronaut’s ability to successfully complete requirements associated with these missions. It has also been found that irradiation can lead to increases in oxidative stress, similar to that seen in the aging brain. Given that astronauts are often middle-aged or older it is important to determine if their age puts them at higher risk for the potentially hazardous effects of exposure to HZE particles. Therefore, we exposed young and old rats to either 1 or 2 Gy of 56Fe irradiation and evaluated performance in a spatial learning and memory task, in addition to examining levels of dopamine (DA) release from superfused striatal slices. Results indicated that exposure to 56Fe particles can produce alterations in behavior and neuronal signaling and that these alterations may be more apparent in older organisms, a finding which suggests that the aging brain may be more susceptible to the deleterious effects of irradiation on performance. Therefore, age may be a factor for consideration in planning long-term missions into space.

  1. Systematic Investigation of the Superconducting Behavior in Aged PuCoGa{sub 5}

    SciTech Connect

    Jutier, Frederic; Colineau, Eric; Griveau, Jean-Christophe; Rebizant, Jean; Wastin, Franck

    2007-07-01

    In this work, we have undertaken to follow the evolution of the PuCoGa{sub 5} superconducting behavior as a function of the damages created by self-radiation effects induced from the Pu-decay. It is shown that the critical temperature is particularly sensitive with ageing. Ageing effects on fundamental parameters such as the lattice parameters of the PuCoGa{sub 5} and the electrical resistivity provide some new hints of the unconventional character of the superconductivity in this class of materials. (authors)

  2. Study on the behavior and mechanism of polycarbonate with hot-water aging

    NASA Astrophysics Data System (ADS)

    Kong, L. P.; Zhao, Y. X.; Zhou, C. H.; Huang, Y. H.; Tang, M.; Gao, J. G.

    2016-07-01

    The present work was concerned with hot-water aging behavior and mechanism of Bisphenol A polycarbonate (PC) used as food and packaging materials. It indicated that with the aging time prolonged, PC sample had internal defects and the mechanical properties of PC materials changed not too much, molecular weight decreased, thermal stability declined. Phenolic hydroxyl absorption intensity enhanced in IR spectra and the maximum absorption wavelength red shift of benzene in UV-Vis spectra, the level of BPA increased. The color change of PC sample was not apparent.

  3. Impact of Inuit customary adoption on behavioral problems in school-age Inuit children

    PubMed Central

    Decaluwe, Béatrice; Jacobson, Sandra W.; Poirier, Marie-Andrée; Forget-Dubois, Nadine; Jacobson, Joseph L.; Muckle, Gina

    2015-01-01

    A large proportion of Inuit children in Arctic Quebec are adopted in accordance with traditional Inuit customs. In contrast to adoptions in Southern Canada and the USA, the child is adopted at birth and by a close family member; he/she knows who his/her biological parents are, and will typically have contact with them. Studies of other populations have reported an increased incidence of behavior problems in adopted compared with non-adopted children. Objectives This study examined the actual extent of the increase in the number of behavior problems seen in Inuit children adopted in accordance with traditional customs. Methods In a prospective longitudinal study conducted in the Canadian Arctic (n = 46 adopted and 231 non-adopted children), prenatal and familial variables were documented at birth and at school age (M = 11.3 years). Behavior problems were assessed on the Teacher Report Form of the Child Behavior Checklist. Results Adopted children lived in more economically disadvantaged families, but their caregivers were less prone to depression, domestic violence, or alcohol abuse compared with those of the non-adopted children. The adoption status was not related to the teacher’s report of attention problems, externalizing or internalizing behaviors, after controlling for confounders. Conclusion Despite less favorable socioeconomic circumstances, a higher extent of behavioral problems was not seen at school age in Inuit children adopted at birth by a family member. Psychosocial stressors associated with adoption are more likely to be responsible for an association with higher levels of childhood behavior problems rather than adoption per se. PMID:25985112

  4. Behavioral Autonomy Age Expectations among Mexican-Origin Mother-Daughter Dyads: An Examination of Within-Group Variability

    ERIC Educational Resources Information Center

    Bamaca-Colbert, Mayra Y.; Umana-Taylor, Adriana J.; Espinosa-Hernandez, Graciela; Brown, Ashley M.

    2012-01-01

    This study examined differences in behavioral autonomy age expectations between Mexican-origin mothers and their adolescent daughters (N = 319 dyads); variability in behavioral autonomy age expectations as a function of nativity and maternal educational attainment also was examined. Findings indicated significant differences between mothers and…

  5. School Entry Age and Children's Social-Behavioral Skills: Evidence From a National Longitudinal Study of U.S. Kindergartners

    ERIC Educational Resources Information Center

    Datar, Ashlesha; Gottfried, Michael A.

    2015-01-01

    Prior research evaluating school entry age effects has largely overlooked the effects on social-behavioral skills despite the growing recognition of returns to such skills. This study is the first to examine the effects of kindergarten entry age on children's social-behavioral outcomes using 9 years of panel data on a national sample of U.S.…

  6. Clarifying the Associations between Age at Menarche and Adolescent Emotional and Behavioral Problems

    PubMed Central

    Van Hulle, Carol A.; Beasley, William H.; Rodgers, Joseph L.; D’Onofrio, Brian M.

    2015-01-01

    Better understanding risk factors for the development of adolescent emotional and behavioral problems can help with intervention and prevention efforts. Previous studies have found that an early menarcheal age predicts several adolescent problems, including depressive symptoms, delinquency, and early age at first intercourse. Few studies, nevertheless, have explicitly tested (a) whether the associations with menarcheal age vary across racial/ethnic groups or (b) whether the sources of the associations are within-families (i.e., consistent with a direct, causal link) or only between-families (i.e., due to selection or confounding factors). The current study analyzed data from a nationally representative US Sample of females (N = 5,637). We examined whether race/ethnicity moderated the associations between early menarche and several adolescent problems by using multiple-group analyses and we examined the degree to which genetic and environmental factors shared by family members account for the associations by comparing sisters and cousins with differing menarcheal ages. Menarcheal age predicted subsequent depressive symptoms, delinquency, and early age at first intercourse in the population. The magnitudes of the associations were similar across all racial/ethnic groups for all outcomes. The within-family associations (i.e., when comparing siblings and cousins with different menarcheal age) were large and statistically significant when predicting early intercourse, but not the other outcomes. The findings suggest that selection or confounding factors account for the associations between menarcheal age and subsequent depressive symptoms and delinquency, whereas the independent association between menarcheal age and early age at first intercourse is consistent with a direct, causal effect. PMID:25687264

  7. Older lesbian sexuality: identity, sexual behavior, and the impact of aging.

    PubMed

    Averett, Paige; Yoon, Intae; Jenkins, Carol L

    2012-01-01

    In response to the very limited and mostly outdated literature on older lesbian sexuality, this exploratory study examined older lesbian sexual identity, romantic relationships, the impact of aging, and experiences of discrimination within these contexts. Utilizing an online survey that recruited via numerous online lesbian communities and snowball sampling, 456 lesbians over the age of 50 responded to closed, Likert scale, and open-ended questions that provided a preliminary understanding of older lesbian sexuality. The results indicated that older lesbians have experienced fluidity in past romantic and sexual relationships, as well as in erotic fantasies, despite strong identification with being lesbian. The findings also indicate a decreased focus on sexuality in the context of relationships, with more focus on stability and continuity. Future research is needed that provides greater specificity and detail about older lesbian conceptions of sexual behavior and sexual identity labels, as well as specific sexual behaviors. PMID:21707407

  8. Socio-behavioral determinants of oral hygiene practices among USA ethnic and age groups.

    PubMed

    Davidson, P L; Rams, T E; Andersen, R M

    1997-05-01

    In this study, socio-behavioral determinants of oral hygiene practices were examined across several dentate ethnic and age groups. Oral hygiene scale scores were constructed from toothbrushing and dental floss frequencies self-reported by population-based samples of middle-aged (35-44 years) and older (65-74 years) dentate adults representing Baltimore African-American and White, San Antonio Hispanic and non-Hispanic White, and Navajo and Lakota Native American persons participating in the WHO International Collaborative Study of Oral Health Outcomes (ICS-II) survey. Female gender, education, certain oral health beliefs, household income, and the presence of a usual source of care were revealed with multivariate analysis to show a significant positive relationship with higher oral hygiene scale scores (indicating better personal oral hygiene practices). Other socio-behavioral variables exhibited a more varied, ethnic-specific pattern of association with oral hygiene scale scores. PMID:9549990

  9. Colony Defense Behavior of the Primitively Eusocial Wasp, Mischocyttarus cerberus is Related to Age

    PubMed Central

    Togni, Olga Coutinho; Giannotti, Edilberto

    2010-01-01

    The colony defense behavior of the wasp Mischocyttarus cerberus Richards (Hymenoptera, Vespidae) was studied to verify whether there were different reactions of wasps of different ages and hierarchical positions during attacks of ants. Detailed nest mapping was first performed, then the wasps were marked and were divided in four distinct categories: queens, older workers, younger workers and males. Tests were made simulating attacks of ants in the nests. The main results showed that the M. cerberus behaviors against ant attacks is more related to the age of the wasps than to their hierarchical position. The oldest wasps (queens and older workers) defend the nest more than the younger workers and males, representing a form of temporal polyethism. PMID:20883135

  10. Neural changes associated with semantic processing in healthy aging despite intact behavioral performance.

    PubMed

    Lacombe, Jacinthe; Jolicoeur, Pierre; Grimault, Stephan; Pineault, Jessica; Joubert, Sven

    2015-10-01

    Semantic memory recruits an extensive neural network including the left inferior prefrontal cortex (IPC) and the left temporoparietal region, which are involved in semantic control processes, as well as the anterior temporal lobe region (ATL) which is considered to be involved in processing semantic information at a central level. However, little is known about the underlying neuronal integrity of the semantic network in normal aging. Young and older healthy adults carried out a semantic judgment task while their cortical activity was recorded using magnetoencephalography (MEG). Despite equivalent behavioral performance, young adults activated the left IPC to a greater extent than older adults, while the latter group recruited the temporoparietal region bilaterally and the left ATL to a greater extent than younger adults. Results indicate that significant neuronal changes occur in normal aging, mainly in regions underlying semantic control processes, despite an apparent stability in performance at the behavioral level. PMID:26282079

  11. Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites

    NASA Astrophysics Data System (ADS)

    Dey, Vikram

    The motivation of this work is based on development of new construction products with strain hardening cementitious composites (SHCC) geared towards sustainable residential applications. The proposed research has three main objectives: automation of existing manufacturing systems for SHCC laminates; multi-level characterization of mechanical properties of fiber, matrix, interface and composites phases using servo-hydraulic and digital image correlation techniques. Structural behavior of these systems were predicted using ductility based design procedures using classical laminate theory and structural mechanics. SHCC sections are made up of thin sections of matrix with Portland cement based binder and fine aggregates impregnating continuous one-dimensional fibers in individual or bundle form or two/three dimensional woven, bonded or knitted textiles. Traditional fiber reinforced concrete (FRC) use random dispersed chopped fibers in the matrix at a low volume fractions, typically 1-2% to avoid to avoid fiber agglomeration and balling. In conventional FRC, fracture localization occurs immediately after the first crack, resulting in only minor improvement in toughness and tensile strength. However in SHCC systems, distribution of cracking throughout the specimen is facilitated by the fiber bridging mechanism. Influence of material properties of yarn, composition, geometry and weave patterns of textile in the behavior of laminated SHCC skin composites were investigated. Contribution of the cementitious matrix in the early age and long-term performance of laminated composites was studied with supplementary cementitious materials such as fly ash, silica fume, and wollastonite. A closed form model with classical laminate theory and ply discount method, coupled with a damage evolution model was utilized to simulate the non-linear tensile response of these composite materials. A constitutive material model developed earlier in the group was utilized to characterize and

  12. Beneficial behavioral, neurochemical and molecular effects of 1-(R)-aminoindan in aged mice.

    PubMed

    Badinter, Felix; Amit, Tamar; Bar-Am, Orit; Youdim, Moussa B H; Weinreb, Orly

    2015-12-01

    Previous neuroprotective studies demonstrated that 1-(R)-aminoindan (AI), which is the major metabolite of the anti-Parkinsonian drug rasagiline, possesses beneficial pharmacological effects in various cell culture and animal models of neurodegeneration. The present study was aimed at investigating the possible neuroprotective effects of AI on cognitive impairments and neurochemical alterations in aged mice. Our findings provide evidence that following chronic systemic treatment with AI (5 mg/kg; daily; 3 months) of aged mice (24 months old), the compound exerted a significant positive impact on neuropsychiatric functions and cognitive behavior deficits, assessed in a variety of tasks (spatial learning and memory retention, working memory, learning abilities and nest building behavior) and produced an antidepressant-like effect. In addition, chronic AI treatment significantly enhanced expression levels of neurotrophins, including brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF), tyrosine kinase- B (Trk-B) receptor and synaptic plasticity markers, such as synapsin-1 and growth-associated protein-43 (GAP-43) in the striatum and hippocampus in aged mice. Our results also indicate that AI treatment up-regulated the expression levels of the pro-survival Bcl-2 mRNA, increased the anti-apoptotic index Bcl-2/Bax and enhanced the activity of the antioxidant enzyme catalase in the brain of aged mice. These effects of AI were also confirmed in aged rats (24 months old). Altogether, the present findings indicate that AI can induce neuroprotective effects on age-related alterations in neurobehavioral functions and exerts neurotrophic up-regulatory and anti-apoptotic properties in aged animals. PMID:26087462

  13. Trajectories of Adolescent Mother–Grandmother Psychological Conflict During Early Parenting and Children's Problem Behaviors at Age 7

    PubMed Central

    Buckingham-Howes, Stacy; Oberlander, Sarah E.; Hurley, Kristen M.; Fitzmaurice, Shannon; Black, Maureen M.

    2016-01-01

    This study extends the determinants of parenting model to adolescent mothers by examining how adolescent mother–grandmother psychological conflict and perceptions of infant fussiness from birth through age 2 years relate to children's problem behaviors at age 7. Participants were 181 adolescent mother, child, and grandmother triads living in multigenerational households and recruited at delivery. Psychological conflict was characterized by two stable trajectories. In multivariate models that included maternal depression, both psychological conflict and perceptions of infant fussiness predicted externalizing behavior at age 7. Perceptions of infant fussiness, but not psychological conflict, predicted internalizing behavior at age 7. PMID:21534055

  14. Effect of an organic additive on the rheology of an aluminous cement paste and consequences on the densification of the hardened material

    NASA Astrophysics Data System (ADS)

    El Hafiane, Y.; Smith, A.; Bonnet, J. P.; Tanouti, B.

    2005-03-01

    The material used in the present work is Secar 71 (Lafarge) mixed with water containing an organic additive (acetic acid noted HOAc). The rheological behavior of these pastes is studied. The best dispersion is obtained when the mass content of the additive with respect to the cement is equal to 0.5%. The microstructural characterizations of samples aged 4 days at 20° C and 95 % relative humidity reveal a significant increase in the density and a reduction in porosity for very small percentages of additive. The remarkable effect of the acetic acid on the microstructure of hardened material is correlated with its good dispersing action.

  15. Effects of voluntary wheel running on LPS-induced sickness behavior in aged mice.

    PubMed

    Martin, Stephen A; Pence, Brandt D; Greene, Ryan M; Johnson, Stephanie J; Dantzer, Robert; Kelley, Keith W; Woods, Jeffrey A

    2013-03-01

    Peripheral stimulation of the innate immune system with LPS causes exaggerated neuroinflammation and prolonged sickness behavior in aged mice. Regular moderate intensity exercise has been shown to exert anti-inflammatory effects that may protect against inappropriate neuroinflammation and sickness in aged mice. The purpose of this study was to test the hypothesis that voluntary wheel running would attenuate LPS-induced sickness behavior and proinflammatory cytokine gene expression in ~22-month-old C57BL/6J mice. Mice were housed with a running wheel (VWR), locked-wheel (Locked), or no wheel (Standard) for 10 weeks, after which they were intraperitoneally injected with LPS across a range of doses (0.02, 0.08, 0.16, 0.33 mg/kg). VWR mice ran on average 3.5 km/day and lost significantly more body weight and body fat, and increased their forced exercise tolerance compared to Locked and Shoebox mice. VWR had no effect on LPS-induced anorexia, adipsia, weight-loss, or reductions in locomotor activity at any LPS dose when compared to Locked and Shoebox groups. LPS induced sickness behavior in a dose-dependent fashion (0.33>0.02 mg/kg). Twenty-four hours post-injection (0.33 mg/kg LPS or Saline) we found a LPS-induced upregulation of whole brain TNFα, IL-1β, and IL-10 mRNA, and increased IL-1β and IL-6 in the spleen and liver; these effects were not attenuated by VWR. We conclude that VWR does not reduce LPS-induced exaggerated or prolonged sickness behavior in aged animals, or 24h post-injection (0.33 mg/kg LPS or Saline) brain and peripheral proinflammatory cytokine gene expression. The necessity of the sickness response is critical for survival and may outweigh the subtle benefits of exercise training in aged animals. PMID:23277090

  16. Aging in Place vs. Relocation for Older Adults with Neurocognitive Disorder: Applications of Wiseman's Behavioral Model.

    PubMed

    Kaplan, Daniel B; Andersen, Troy Christian; Lehning, Amanda J; Perry, Tam E

    2015-01-01

    Some older adults are more vulnerable to housing concerns due to physical and cognitive challenges, including those with a neurocognitive disorder who need extensive support. Environmental gerontology frameworks, including Wiseman's 1980 Behavioral Model of Elderly Migration, have informed scholarship on aging in place and relocation. Understanding Wiseman's model, including considerations for working with families confronting a neurocognitive disorder, can help practitioners ensure that older clients live in settings that best meet their wants and needs. PMID:26016530

  17. Fatigue hardening in niobium single crystals.

    NASA Technical Reports Server (NTRS)

    Doner, M.; Diprimio, J. C.; Salkovitz, E. I.

    1973-01-01

    Nb single crystals of various orientations were cyclically deformed in tension-compression under strain control. At low strain amplitudes all crystals oriented for single slip and some oriented for multiple slip showed a two stage hardening. When present, the first stage was characterized with almost no cyclic work hardening. The rate of hardening in the second stage increased with strain amplitude and the amount of secondary slip. In crystals oriented for single slip kink bands developed on their side faces during rapid hardening stage which resulted in considerable amount of asterism in Laue spots. A cyclic stress-strain curve independent of prior history was found to exist which was also independent of crystal orientation. Furthermore, this curve differed only slightly from that of polycrystalline Nb obtained from data in literature.

  18. Alloy solution hardening with solute pairs

    DOEpatents

    Mitchell, John W.

    1976-08-24

    Solution hardened alloys are formed by using at least two solutes which form associated solute pairs in the solvent metal lattice. Copper containing equal atomic percentages of aluminum and palladium is an example.

  19. Process for hardening the surface of polymers

    DOEpatents

    Mansur, L.K.; Lee, E.H.

    1992-07-14

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance. 1 figure.

  20. Process for hardening the surface of polymers

    DOEpatents

    Mansur, Louis K.; Lee, Eal H.

    1992-01-01

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance.

  1. Small for gestational age as a predictor of behavioral and learning problems in twins.

    PubMed

    Rooney, Rosanna; Hay, David; Levy, Florence

    2003-02-01

    The study examines the effects of being born small for gestational age (SGA) on rates of behavioral problems in twins and siblings, utilising data from the Australian Twin Study of disruptive behavior disorders in twins and their siblings. Participants were 3944 twins and their siblings who were assessed at two intervals three years apart. At the first assessment (1991), they ranged between 4 and 12 years of age. Items assessing Attention Deficit/Hyperactivity Disorder were based on DSM-III-R criteria (Time 1) and DSM-IV criteria (Time 2). Other measures included history of speech and reading therapy, demographic information and obstetric and neonatal history. Results indicated that both male and female twins, who were extremely growth restricted (small for gestational age up to the third percentile-WGA3) showed more inattention, and poorer speech and reading scores. The effects were greater for males. Male twins who were small for gestation age, up to the 10th percentile, were more likely to have a DSM-IV diagnosis of Inattention. Implications of these results included WGA3 male twins being at a "triple disadvantage" for subsequent behavioral and learning problems, in that being male, being a twin and being small for gestational age are all significant factors. Recommendations are made for early intervention for low birthweight male twins. The study is consistent with recent follow-up studies of very-low-birthweight singletons, indicating male disadvantage in cognitive outcome. While there is some genetic component to SGA, it does constitute a potentially major contribution to common environmental effects that must be considered in twin-based genetic analyses. PMID:12626228

  2. The Developmental Course of Illicit Substance Use from Age 12 to 22: Links with Depressive, Anxiety, and Behavior Disorders at Age 18

    ERIC Educational Resources Information Center

    Lansford, Jennifer E.; Erath, Stephen; Yu, Tianyi; Pettit, Gregory S.; Dodge, Kenneth A.; Bates, John E.

    2008-01-01

    Background: Previous theory and research suggest links between substance use and externalizing behavior problems, but links between substance use and internalizing problems are less clear. The present study sought to understand concurrent links among diagnoses of substance use disorders, internalizing disorders, and behavior disorders at age 18 as…

  3. Decline in Radiation Hardened Microcircuit Infrastructure

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.

    2015-01-01

    Two areas of radiation hardened microcircuit infrastructure will be discussed: 1) The availability and performance of radiation hardened microcircuits, and, and 2) The access to radiation test facilities primarily for proton single event effects (SEE) testing. Other areas not discussed, but are a concern include: The challenge for maintaining radiation effects tool access for assurance purposes, and, the access to radiation test facilities primarily for heavy ion single event effects (SEE) testing. Status and implications will be discussed for each area.

  4. Effects of gun admonitions on the behaviors and attitudes of school-aged boys.

    PubMed

    Hardy, Marjorie S

    2003-10-01

    Gun-safety programs frequently warn children not to touch guns with little consideration that the messages may enhance the allure of the guns. In the current study, boys rated and ranked their preference for a gun in comparison with other desirable objects. One week later, when left alone in the room with the objects, they were forbidden to touch either the gun or some other object. Observations of their behavior and reevaluation of their attitudes followed. Although the boys forbidden to touch the gun did not report an increased preference for it, all participants were significantly more likely to touch the forbidden gun than to touch other forbidden objects. Age, parent- and coach-reported simulated gun-play, and coach-reported risky behavior predicted gun-touching behavior. The results of the current study indicate that guns hold a unique allure and cast further doubt on the ability of gun admonitions to keep children safe around guns. PMID:14578696

  5. Developmental Risk and Young Children’s Regulatory Strategies: Predicting Behavior Problems at Age Five

    PubMed Central

    Gerstein, Emily D.; Arbona, Anita Pedersen y; Crnic, Keith A.; Ryu, Ehri; Baker, Bruce L.; Blacher, Jan

    2013-01-01

    Children with early developmental delays are at heightened risk for behavior problems and comorbid psychopathology. This study examined the trajectories of regulatory capabilities and their potentially mediating role in the development of behavior problems for children with and without early developmental delays. A sample of 231 children comprised of 137 typically developing children and 94 children with developmental delays were examined during mildly frustrating laboratory tasks across the preschool period (ages 3–5). Results indicated that children with delays had greater use of maladaptive strategies (distraction, distress venting) and lower use of adaptive strategies (constructive coping) than typically developing children. For both groups, strategies had similar rates of growth across time; maladaptive strategies decreased and adaptive strategies increased. The intercept of strategy use, but not the slope, was found to mediate the relation between developmental risk and externalizing behaviors. Findings support that dysregulation, rather than the developmental risk, may be responsible for the high levels of comorbid psychopathology. PMID:21107675

  6. Preschool-Aged Children with Iron Deficiency Anemia Show Altered Affect and Behavior1,2

    PubMed Central

    Lozoff, Betsy; Corapci, Feyza; Burden, Matthew J.; Kaciroti, Niko; Angulo-Barroso, Rosa; Sazawal, Sunil; Black, Maureen

    2012-01-01

    This study compared social looking and response to novelty in preschool-aged children (47–68 mo) with or without iron deficiency anemia (IDA). Iron status of the participants from a low-income community in New Delhi, India, was based on venous hemoglobin, mean corpuscular volume, and red cell distribution width. Children’s social looking toward adults, affect, and wary or hesitant behavior in response to novelty were assessed in a semistructured paradigm during an in-home play observation. Affect and behavior were compared as a function of iron status: IDA (n = 74) vs. nonanemic (n = 164). Compared with nonanemic preschoolers, preschoolers with IDA displayed less social looking toward their mothers, moved close to their mothers more quickly, and were slower to display positive affect and touch novel toys for the first time. These results indicate that IDA in the preschool period has affective and behavioral effects similar to those reported for IDA in infancy. PMID:17311960

  7. Effect of aging and deformation on the microstructure and properties of Fe-Ni-Ti maraging steel

    NASA Astrophysics Data System (ADS)

    Shekhter, A.; Aaronson, H. I.; Miller, M. K.; Ringer, S. P.; Pereloma, E. V.

    2004-03-01

    The age-hardening behavior of Fe-25.3Ni-1.7 Ti (wt pct) alloy both in undeformed specimens and in specimens cold deformed by 10 or 20 pct prior to aging was studied. The microstructural changes during aging were observed using transmission electron microscopy (TEM) and atom probe analysis and there were related to the mechanical properties as measured by microhardness and shear punch testing. An excellent combination of hardness, strength, and ductility was achieved after only 5 seconds aging at 550°C. We propose that this rapid strengthening is due to a dislocation friction effect arising from the formation of a fine dispersion of Ni-Ti atomic co-clusters during this short aging time. The concomitant effects of a reverse transformation of martensite to austenite during aging and a gradual increase in both size of the clusters and distance between them contributed to a decrease in strength after aging for 15 seconds. This decline proceeded until aging for 300 seconds and was followed by a secondary hardening reaction toward peak hardness (at 10,800 seconds) and subsequent overaging. This secondary hardening was associated with fine-scale precipitation of Ni3Ti and this process was accelerated by deformation prior to aging, leading to a reduction or elimination of hardness decline after the initial cluster hardening.

  8. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  9. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  10. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  11. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  12. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  13. Influence of temperature, environment, and thermal aging on the continuous cycle fatigue behavior of Hastelloy X and Inconel 617

    SciTech Connect

    Strizak, J.P.; Brinkman, C.R.; Booker, M.K.; Rittenhouse, P.L.

    1982-04-01

    Results are presented for strain-controlled fatigue and tensile tests for two nickel-base, solution-hardened reference structural alloys for use in several High-Temperature Gas-Cooled Reactor (HTGR) concepts. These alloys, Hastelloy X and Inconel 617, were tested from room temperature to 871/sup 0/C in air and impure helium. Materials were tested in both the solution-annealed and the preaged conditios, in which aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are given between the strain-controlled fatigue lives of these and several other commonly used alloys, all tested at 538/sup 0/C. An analysis is also presented of the continuous cycle fatigue data obtained from room temperature to 427/sup 0/C for Hastelloy G, Hastelloy X, Hastelloy C-276, and Hastelloy C-4, an effort undertaken in support of ASME code development.

  14. Laser Surface Hardening of AISI 1045 Steel

    NASA Astrophysics Data System (ADS)

    Li, Ruifeng; Jin, Yajuan; Li, Zhuguo; Qi, Kai

    2014-09-01

    The study investigates laser surface hardening in the AISI 1045 steel using two different types of industrial laser: a high-power diode laser (HPDL) and a CO2 laser, respectively. The effect of process parameters such as beam power, travel speed on structure, case depth, and microhardness was examined. In most cases, a heat-affected zone (HAZ) formed below the surface; a substantial increase in surface hardness was achieved. In addition, big differences were found between the hardened specimens after HPDL surface hardening and CO2 laser surface hardening. For HPDL, depths of the HAZ were almost equal in total HAZ o, without surface melting. For CO2 laser, the depths changed a lot in the HAZ, with surface melting in the center. To better understand the difference of laser hardening results when use these two types of laser, numerical (ANSYS) analysis of the heat conduction involved in the process was also studied. For HPDL method, a rectangular beam spot and uniform energy distribution across the spot were assumed, while for CO2 laser, a circular beam spot and Gaussian energy distribution were assumed. The results showed that the energy distribution variety altered the thermal cycles of the HAZ dramatically. The rectangular HPDL laser beam spot with uniform energy distribution is much more feasible for laser surface hardening.

  15. Circuit mechanisms encoding odors and driving aging-associated behavioral declines in Caenorhabditis elegans

    PubMed Central

    Leinwand, Sarah G; Yang, Claire J; Bazopoulou, Daphne; Chronis, Nikos; Srinivasan, Jagan; Chalasani, Sreekanth H

    2015-01-01

    Chemosensory neurons extract information about chemical cues from the environment. How is the activity in these sensory neurons transformed into behavior? Using Caenorhabditis elegans, we map a novel sensory neuron circuit motif that encodes odor concentration. Primary neurons, AWCON and AWA, directly detect the food odor benzaldehyde (BZ) and release insulin-like peptides and acetylcholine, respectively, which are required for odor-evoked responses in secondary neurons, ASEL and AWB. Consistently, both primary and secondary neurons are required for BZ attraction. Unexpectedly, this combinatorial code is altered in aged animals: odor-evoked activity in secondary, but not primary, olfactory neurons is reduced. Moreover, experimental manipulations increasing neurotransmission from primary neurons rescues aging-associated neuronal deficits. Finally, we correlate the odor responsiveness of aged animals with their lifespan. Together, these results show how odors are encoded by primary and secondary neurons and suggest reduced neurotransmission as a novel mechanism driving aging-associated sensory neural activity and behavioral declines. DOI: http://dx.doi.org/10.7554/eLife.10181.001 PMID:26394000

  16. AGING BEHAVIOR OF VITON O-RING SEALS IN THE 9975 SHIPPING PACKAGE

    SciTech Connect

    Skidmore, E.; Daugherty, W.; Hoffman, E.; Dunn, K.; Bellamy, S.

    2012-01-13

    The Savannah River Site (SRS) is storing plutonium (Pu) materials in the K-Area Materials Storage (KAMS) facility. The Pu materials were packaged according to the DOE-STD-3013 standard and shipped to the SRS in Type B 9975 packages. The robust 9975 shipping package was not designed for long-term product storage, but it is a specified part of the storage configuration and the KAMS facility safety basis credits the 9975 design with containment. Within the 9975 package, nested stainless steel containment vessels are closed with dual O-ring seals based on Viton{reg_sign} GLT or GLT-S fluoroelastomer. The aging behavior of the O-ring compounds is being studied to provide the facility with advanced notice of nonconformance and to develop life prediction models. A combination of field surveillance, leak testing of surrogate fixtures aged at bounding service temperatures, and accelerated-aging methodologies based on compression stress-relaxation and oxygen consumption analysis is being used to evaluate seal performance. A summary of the surveillance program relative to seal aging behavior is presented.

  17. Possible influence of sulfur content on magnetic aging behaviors of non-oriented electrical steels

    NASA Astrophysics Data System (ADS)

    Mao, Wei-Min; Yang, Ping; Li, Chang-Rong

    2013-12-01

    Six non-oriented steel sheets of similar grade produced by different steel companies were used to analyze the magnetic aging behaviors after aging at 200°C for 48 h. It was observed that tiny S atoms, besides C and N, could also induce certain increase of core loss during aging. Thermodynamic calculation indicated that the nucleation driving force of FeS is much higher than those of Fe3C and Fe4N at low temperature, while S atoms, which tend to segregated around dislocations and boundaries, would diffuse rapidly along the crystalline defects while FeS particles would form. Therefore, higher content of tiny S atoms could increase core loss during service time of non-oriented steel sheets.

  18. A new perspective on behavioral inconsistency and neural noise in aging: compensatory speeding of neural communication

    PubMed Central

    Hong, S. Lee; Rebec, George V.

    2012-01-01

    This paper seeks to present a new perspective on the aging brain. Here, we make connections between two key phenomena of brain aging: (1) increased neural noise or random background activity; and (2) slowing of brain activity. Our perspective proposes the possibility that the slowing of neural processing due to decreasing nerve conduction velocities leads to a compensatory speeding of neuron firing rates. These increased firing rates lead to a broader distribution of power in the frequency spectrum of neural oscillations, which we propose, can just as easily be interpreted as neural noise. Compensatory speeding of neural activity, as we present, is constrained by the: (A) availability of metabolic energy sources; and (B) competition for frequency bandwidth needed for neural communication. We propose that these constraints lead to the eventual inability to compensate for age-related declines in neural function that are manifested clinically as deficits in cognition, affect, and motor behavior. PMID:23055970

  19. Aging Behavior of Ni-Electrode Multilayer Ceramic Capacitors with X7R Characteristics

    NASA Astrophysics Data System (ADS)

    Nomura, Takeshi; Kawano, Naoki; Yamamatsu, Junko; Arashi, Tomohiro; Nakano, Yukie; Sato, Akira

    1995-09-01

    Capacitance aging under dc field has been studied on BaTiO3-based dielectrics with X7R characteristics for multilayer ceramic capacitors with Ni internal electrodes. Capacitance change strongly depends on additives and firing conditions as well as microstructure. Aging behavior under no dc field is well explained by Richter's relaxation curve. On the other hand, aging under dc field cannot be fitted by Richter's curve. Therefore, a new model which assumes two factors that affect relaxation is proposed. According to the new model, capacitance changes in two stages, short-term and long-term relaxations. Capacitance change in short-term relaxation strongly depends on applied dc field. On the contrary, that of long-term relaxation does not depend on dc field.

  20. Zinc coated sheet steel for press hardening

    NASA Astrophysics Data System (ADS)

    Ghanbari, Zahra N.

    Galvanized steels are of interest to enhance corrosion resistance of press-hardened steels, but concerns related to liquid metal embrittlement have been raised. The objective of this study was to assess the soak time and temperature conditions relevant to the hot-stamping process during which Zn penetration did or did not occur in galvanized 22MnB5 press-hardening steel. A GleebleRTM 3500 was used to heat treat samples using hold times and temperatures similar to those used in industrial hot-stamping. Deformation at both elevated temperature and room temperature were conducted to assess the coating and substrate behavior related to forming (at high temperature) and service (at room temperature). The extent of alloying between the coating and substrate was assessed on undeformed samples heat treated under similar conditions to the deformed samples. The coating transitioned from an α + Gamma1 composition to an α (bcc Fe-Zn) phase with increased soak time. This transition likely corresponded to a decrease in availability of Zn-rich liquid in the coating during elevated temperature deformation. Penetration of Zn into the substrate sheet in the undeformed condition was not observed for any of the processing conditions examined. The number and depth of cracks in the coating and substrate steel was also measured in the hot-ductility samples. The number of cracks appeared to increase, while the depth of cracks appeared to decrease, with increasing soak time and increasing soak temperature. The crack depth appeared to be minimized in the sample soaked at the highest soak temperature (900 °C) for intermediate and extended soak times (300 s or 600 s). Zn penetration into the substrate steel was observed in the hot-ductility samples soaked at each hold temperature for the shortest soak time (10 s) before being deformed at elevated temperature. Reduction of area and elongation measurements showed that the coated sample soaked at the highest temperature and longest soak time

  1. Dietary and behavioral interventions protect against age related activation of caspase cascades in the canine brain.

    PubMed

    Snigdha, Shikha; Berchtold, Nicole; Astarita, Giuseppe; Saing, Tommy; Piomelli, Daniele; Cotman, Carl W

    2011-01-01

    Lifestyle interventions such as diet, exercise, and cognitive training represent a quietly emerging revolution in the modern approach to counteracting age-related declines in brain health. Previous studies in our laboratory have shown that long-term dietary supplementation with antioxidants and mitochondrial cofactors (AOX) or behavioral enrichment with social, cognitive, and exercise components (ENR), can effectively improve cognitive performance and reduce brain pathology of aged canines, including oxidative damage and Aβ accumulation. In this study, we build on and extend our previous findings by investigating if the interventions reduce caspase activation and ceramide accumulation in the aged frontal cortex, since caspase activation and ceramide accumulation are common convergence points for oxidative damage and Aβ, among other factors associated with the aged and AD brain. Aged beagles were placed into one of four treatment groups: CON--control environment/control diet, AOX--control environment/antioxidant diet, ENR--enriched environment/control diet, AOX/ENR--enriched environment/antioxidant diet for 2.8 years. Following behavioral testing, brains were removed and frontal cortices were analyzed to monitor levels of active caspase 3, active caspase 9 and their respective cleavage products such as tau and semaphorin7a, and ceramides. Our results show that levels of activated caspase-3 were reduced by ENR and AOX interventions with the largest reduction occurring with combined AOX/ENR group. Further, reductions in caspase-3 correlated with reduced errors in a reversal learning task, which depends on frontal cortex function. In addition, animals treated with an AOX arm showed reduced numbers of cells expressing active caspase 9 or its cleavage product semaphorin 7A, while ENR (but not AOX) reduced ceramide levels. Overall, these data demonstrate that lifestyle interventions curtail activation of pro-degenerative pathways to improve cellular health and are the

  2. Static Strain Aging Behavior of a Manganese-Silicon Steel After Single and Multi-stage Straining

    NASA Astrophysics Data System (ADS)

    Seraj, P.; Serajzadeh, S.

    2016-03-01

    In this work, static strain aging behavior of an alloy steel containing high amounts of silicon and manganese was examined while the influences of initial microstructure and pre-strain on the aging kinetics were evaluated as well. The rate of strain aging in a low carbon steel was also determined and compared with that occurred in the alloy steel. The rates of static strain aging in the steels were defined at room temperature and at 95 °C by means of double-hit tensile testing and hardness measurements. In addition, three-stage aging experiments at 80 °C were carried out to estimate aging behavior under multi-pass deformation processing. The results showed that in-solution manganese and silicon atoms could significantly affect the aging behavior of the steel and reduce the kinetics of static strain aging as compared to the low carbon steel. The initial microstructure also played an important role on the aging behavior. The rapidly cooled steel having mean ferrite grain size of 9.7 μm showed the least aging susceptibility index during the aging experiments. Accordingly, the activation energies for static strain aging were calculated as 93.2 and 85.7 kJ/mole for the alloy steel having fine and coarse ferrite-pearlite structures, respectively while it was computed as 79.1 kJ/mole for the low carbon steel with ferrite mean grain size of about 16.2 μm.

  3. Family Emotional Climate and Sibling Relationship Quality: Influences on Behavioral Problems and Adaptation in Preschool-Aged Children

    ERIC Educational Resources Information Center

    Modry-Mandell, Kerri L.; Gamble, Wendy C.; Taylor, Angela R.

    2007-01-01

    We examined the impact of family emotional climate and sibling relationship quality on behavioral problems and adaptation in preschool-aged children. Participants were 63 mothers with a preschool-aged child enrolled in a Southern Arizona Head Start Program. Siblings were identified as children closest in age to target child. Mothers of…

  4. Impaired burrowing is the most prominent behavioral deficit of aging htau mice.

    PubMed

    Geiszler, Philippine Camilla; Barron, Matthew Richard; Pardon, Marie-Christine

    2016-08-01

    htau mice are deficient of murine tau but express all six human tau isoforms, leading to gradual tau misprocessing and aggregation in brain areas relevant to Alzheimer's disease. While histopathological changes in htau mice have been researched in the past, we focused here on functional consequences of human tau accumulation. htau mice and their background controls - murine tau knock-out (mtau(-/-)) and C57Bl/6J mice - underwent a comprehensive trial battery to investigate species-specific behavior, locomotor activity, emotional responses, exploratory traits, spatial and recognition memory as well as acquisition, retention and extinction of contextual fear at two, four, six, nine and twelve months of age. In htau mice, tau pathology was already present at two months of age, whereas deficits in food burrowing and spatial working memory were first noted at four months of age. At later stages the presence of human tau on a mtau(-/-) background appeared to guard cognitive performance; as mtau(-/-) but not htau mice differed from C57Bl/6J mice in the food burrowing, spontaneous alternation and object discrimination tasks. Aging mtau(-/-) mice also exhibited increased body mass and locomotor activity. These data highlight that reduced food-burrowing performance was the most robust aspect of the htau phenotype with aging. htau and mtau(-/-) deficits in food burrowing pointed at the necessity of intact tau systems for daily life activities. While some htau and mtau(-/-) deficits overlap, age differences between the two genotypes may reflect distinct functional effects and compared to C57Bl/6J mice, the htau phenotype appeared stronger than the mtau(-/-) phenotype at young ages but milder with aging. PMID:27167086

  5. Influence of electrified surface of cementitious materials on structure formation of hardened cement paste

    NASA Astrophysics Data System (ADS)

    Alekseev, A.; Gusakov, A.

    2015-01-01

    To provide high strength and durability of concrete it is necessary to study the influence of physical and chemical and mechanical principles of dispersed cementitious systems. The experimental bench was developed to study the influence of electrified surface of cementitious materials on structure formation of hardened cement paste. The test bench allows accelerating the processes of dissolution of cementing materials in water due to influence of electric discharge on their surface. Cement activation with high-voltage corona discharge when AC current is applied allows increasing the ultimate compressive strength of hardened cement paste by 46% at the age of one day and by 20% at the age of 28 days.

  6. Inflammatory insult during pregnancy accelerates age-related behavioral and neurobiochemical changes in CD-1 mice.

    PubMed

    Li, Xue-Yan; Wang, Fang; Chen, Gui-Hai; Li, Xue-Wei; Yang, Qi-Gang; Cao, Lei; Yan, Wen-Wen

    2016-06-01

    Data shows that inflammation during pregnancy significantly exerts a long-term influence on offspring, such as increasing the risk of adult cognition decline in animals. However, it is unclear whether gestational inflammation affects the neurobehavioral and neurobiochemical outcomes in the mother-self during aging. In this study, pregnant CD-1 mice intraperitoneally received lipopolysaccharide (LPS) in two doses (25 and 50 g/kg, respectively) or normal saline daily during gestational days 15-17. At the age of 15 months, a battery of behavioral tasks was employed to evaluate their species-typical behaviors, sensorimotor ability, anxiety levels, and spatial learning and memory abilities. An immunohistochemical method was utilized preliminarily to detect neurobiochemical indicators consisting of amyloid-β, phosphorylated tau, presynaptic proteins synaptotagmin-1 and syntaxin-1, glial fibrillary acidic protein (GFAP), and histone-4 acetylation on the K8 site (H4K8ac). The behavioral results showed that LPS exposure during pregnancy exacerbated a decline in 15-month-old CD-1 mice's abilities to nest, their sensorimotor and spatial learning and memory capabilities, and increased their anxiety levels. The neurobiochemical results indicated that gestational LPS exposure also intensified age-related hippocampal changes, including increased amyloid-β42, phosphorylated tau, synaptotagmin-1 and GFAP, and decreased syntaxin-1 and H4K8ac. Our results suggested that the inflammatory insult during pregnancy could be an important risk factor for the development of Alzheimer's disease, and the H4K8 acetylation might play an important role in the underlying mechanism. This study offers a perspective for improving strategies that support healthy development and successful aging. PMID:27194408

  7. Effects of diet and behavioral enrichment on free fatty acids in the aged canine brain.

    PubMed

    Snigdha, S; Astarita, G; Piomelli, D; Cotman, C W

    2012-01-27

    Despite several recent studies suggesting that dysregulation of brain lipid metabolism might contribute to the mechanisms of aging and Alzheimer's disease (AD), lipid metabolism has not been evaluated extensively in the aging brain. Here, we use a lipidomic approach to demonstrate that antioxidants plus mitochondrial cofactors treatment, either alone or in combination with behavioral enrichment, attenuates lipid abnormalities in the frontal cortices of aged canine in a manner correlated with cognitive scores. Our analyses revealed that the levels of free palmitoleic acid and nervonic acid were decreased in frontal cortices of aged dogs (n=5-6/group) treated with antioxidant compared with the control group. The monounsaturated/saturated fatty acid ratio, also known as "desaturation index"-an ex-vivo indicator of stearoyl-CoA desaturase activity, was also reduced in the frontal cortex of dogs treated with antioxidants compared with control groups. Increased palmitoleic acid levels and desaturation index were positively correlated with increased reversal learning errors and decreased cognitive performance. In conclusion, our study indicates that the addition of antioxidants and mitochondrial cofactors to the regular diet alters the composition of free fatty acids in the aged brain. Together with data showing increased palmitoleic acid levels in AD patients, our data suggest that reducing palmitoleic acid levels and desaturation index in the brain may be associated with improved cognitive performance. PMID:22183056

  8. Effects of diet & behavioral enrichment on free fatty acids in the aged canine brain

    PubMed Central

    Snigdha, Shikha; Astarita, Giuseppe; Piomelli, Daniele; Cotman, Carl W.

    2012-01-01

    Despite several recent studies suggesting that dysregulation of brain lipid metabolism might contribute to the mechanisms of aging and Alzheimer’s disease (AD), lipid metabolism has not been evaluated extensively in the aging brain. Here, we use a lipidomic approach to demonstrate that antioxidants plus mitochondrial cofactors treatment, either alone or in combination with behavioral enrichment, attenuates lipid abnormalities in the frontal cortices of aged canine in a manner correlated with cognitive scores. Our analyses revealed that the levels of free palmitoleic acid and nervonic acid were decreased in frontal cortices of aged dogs (n=5-6/group) treated with antioxidant compared to the control group. The monounsaturated/saturated fatty acid ratio, also known as ‘desaturation index’ - an ex-vivo indicator of stearoyl-CoA desaturase activity, was also reduced in the frontal cortex of dogs treated with antioxidants compared to control groups. Increased palmitoleic acid levels and desaturation index were positively correlated with increased reversal learning errors and decreased cognitive performance. In conclusion, our study indicates that the addition of antioxidants and mitochondrial cofactors to the regular diet alters the composition of free fatty acids in the aged brain. Together with data showing increased palmitoleic acid levels in AD patients, our data suggest that reducing palmitoleic acid levels and desaturation index in the brain may be associated with improved cognitive performance. PMID:22183056

  9. Point defect concentrations and solid solution hardening in NiAl with Fe additions

    SciTech Connect

    Pike, L.M.; Chang, Y.A.; Liu, C.T.

    1997-08-01

    The solid solution hardening behavior exhibited when Fe is added to NiAl is investigated. This is an interesting problem to consider since the ternary Fe additions may choose to occupy either the Ni or the Al sublattice, affecting the hardness at differing rates. Moreover, the addition of Fe may affect the concentrations of other point defects such as vacancies and Ni anti-sites. As a result, unusual effects ranging from rapid hardening to solid solution softening are observed. Alloys with varying amounts of Fe were prepared in Ni-rich (40 at. % Al) and stoichiometric (50 at. % Al) compositions. Vacancy concentrations were measured using lattice parameter and density measurements. The site occupancy of Fe was determined using ALCHEMI. Using these two techniques the site occupancies of all species could be uniquely determined. Significant differences in the defect concentrations as well as the hardening behavior were encountered between the Ni-rich and stoichiometric regimes.

  10. Stepwise work hardening induced by individual grain boundary in Cu bicrystal micropillars

    PubMed Central

    Li, L. L.; Zhang, Z. J.; Tan, J.; Jiang, C. B.; Qu, R. T.; Zhang, P.; Yang, J. B.; Zhang, Z. F.

    2015-01-01

    Vast experiments have demonstrated that the external specimen size makes a large difference in the deformation behavior of crystalline materials. However, as one important kind of internal planar defects, the role of grain boundary (GB) in small scales needs to be clarified in light of the scarce and inconsistent experimental results at present. Through compression of Cu bicrystal and its counterpart monocrystal micropillars, it is found that, in contrast to the monocrystals, the bicrystals are characterized by work hardening with discrete strain bursts. Interestingly, the stress rise between two adjacent strain bursts of the bicrystals increases with the decrease of specimen size. The results suggest that GBs play a critical role in the work hardening of materials in small scales, which may provide important implications to further understand the general work hardening behaviors of materials in the future. PMID:26490543

  11. Cyclic hardening in copper described in terms of combined monotonic and cyclic stress-strain curves

    SciTech Connect

    Chandler, H.D. . School of Mechanical Engineering)

    1995-01-01

    Hardening of polycrystalline copper subjected to tension-compression loading cycles in the plastic region is discussed with reference to changes in flow stress determined from equations describing dislocation glide. It is suggested that hardening is as a result of the accumulation of strain on a monotonic stress-strain curve. On initial loading, the behavior is monotonic. On stress reversal, a characteristic cyclic stress-strain curve is followed until the stress reaches a value in reverse loading corresponding to the maximum attained during the preceding half cycle. Thereafter, the monotonic path is followed until strain reversal occurs at completion of the half cycle. Repetition of the process results in cyclic hardening. Steady state cyclic behavior is reached when a stress associated with the monotonic stress-strain curve is reached which is equal to the stress associated with the cyclic stress-strain curve corresponding to the imposed strain amplitude.

  12. Aging Behavior of the EPDM O-Rings in the H1616 Shipping Package

    SciTech Connect

    Daugherty, W.; Stefek, T.; Skidmore, E.

    2015-06-09

    The H1616 shipping package is used within the DOE complex for shipping tritium reservoirs. The annual recertification frequency can create logistical difficulties with other constraints on the timing of shipments; thus, a longer re-certification period is desirable. The ethylene propylene diene monomer (EPDM) O-rings used in the H1616 shipping package are being aged and tested at the Savannah River National Laboratory (SRNL) to provide a technical basis for extending the annual maintenance of the H1616 shipping package. H1616 EPDM O-rings are being aged at elevated temperature, and tested for degradation in mechanical properties, compression stress relaxation (CSR) behavior, and leak performance. Mechanical properties of aged O-rings show significant degradation can occur, but an inert atmosphere (argon backfill) greatly reduces the rate of degradation. The CSR behavior of O-rings was evaluated in air at 79 to 177 °C. These collective data were used to develop a predictive model for extrapolation of CSR behavior to relevant service temperatures (<67 °C). O-rings were also aged in H1616 Containment Vessels (CV) in an inert atmosphere at 71 to 149 °C. The vessels are helium leak tested periodically to determine if they continue to remain leak-tight. The vessel tests provide a solid demonstration that the H1616 O-rings will remain leak-tight at temperatures up to 113 °C for up to approximately 2.3 years. Significantly longer periods of leak-tight service are expected at the lower temperatures actually experienced in service. The predictive model developed from the CSR data conservatively indicates a service life of ~5 years at 67 °C. Although the relationship between CSR behavior and leak-tight performance has not been established for this design, the CSR predictions for this O-ring are conservative relative to leak-tight performance. Based on the collective data developed to date, SRNL has recommended that the maintenance interval for the H1616 package be

  13. Effects of physical aging on long-term behavior of composites

    NASA Technical Reports Server (NTRS)

    Brinson, L. Catherine

    1993-01-01

    The HSCT plane, envisioned to have a lifetime of over 60,000 flight hours and to travel at speeds in excess of Mach 2, is the source of intensive study at NASA. In particular, polymer matrix composites are being strongly considered for use in primary and secondary structures due to their high strength to weight ratio and the options of property tailoring. However, an added difficulty in the use of polymer based materials is that their properties change significantly over time, especially at the elevated temperatures that will be experienced during flight, and prediction of properties based on irregular thermal and mechanical loading is extremely difficult. This study focused on one aspect of long-term polymer composite behavior: physical aging. When a polymer is cooled to below its glass transition temperature, the material is not in thermodynamic equilibrium and the free volume and enthalpy evolve over time to approach their equilibrium values. During this time, the mechanical properties change significantly and this change is termed physical aging. This work begins with a review of the concepts of physical aging on a pure polymer system. The effective time theory, which can be used to predict long term behavior based on short term data, is mathematically formalized. The effects of aging to equilibrium are proven and discussed. The theory developed for polymers is then applied first to a unidirectional composite, then to a general laminate. Comparison to experimental data is excellent. It is shown that the effects of aging on the long-term properties of composites can be counter-intuitive, stressing the importance of the development and use of a predictive theory to analyze structures.

  14. Response inhibition difficulties in preterm children aged 9-12 years: Relations with emotion and behavior.

    PubMed

    Réveillon, Morgane; Borradori Tolsa, Cristina; Monnier, Maryline; Hüppi, Petra S; Barisnikov, Koviljka

    2016-01-01

    Previous studies with children have demonstrated inhibition difficulties associated with prematurity, but the question of potentially catching up with a delay in inhibition processes before adolescence still remains. Moreover, preterm adolescents are more at risk than their term-born peers for presenting behavioral problems such as emotional difficulties and attention deficit/hyperactivity disorder. In addition to examining response inhibition, this study addressed, for the first time, the impact of an emotional context on response inhibition abilities and its relation to behavioral problems in late school-aged preterm children. Fifty-eight preterm children aged 9-12 years were compared with 61 controls on two versions of a stop-signal task, the Delay Frustration Task, and the Strengths and Difficulties Questionnaire. Results showed general difficulties in inhibiting a response, rather than a specific impact of emotional context in preterm children. Compared with controls, these children exhibited more and longer button presses in a delay situation, as well as faster go reaction times associated with lower probability of inhibition in the stop-signal tasks. These difficulties reflected impulsivity and were associated with higher hyperactivity/inattention and conduct problems. Additionally, intrauterine growth restriction was found to be an additional perinatal risk factor for hyperactivity/inattention symptoms. These findings suggest that remaining inhibition difficulties in the preterm population at preadolescence could reveal increasing behavioral issues. PMID:25569693

  15. Paternal incarceration and child-reported behavioral functioning at age 9.

    PubMed

    Haskins, Anna R

    2015-07-01

    Within the last few decades our understanding of the importance of non-cognitive skills for socioeconomic success has grown along with our knowledge of the deleterious impacts of paternal incarceration for child wellbeing. Given the importance of early skills and that elementary-aged children constitute the majority of children with incarcerated parents, understanding the connection between paternal incarceration and the socio-emotional component of children's non-cognitive development is pressing. Using matching models, data from the newest wave of the Fragile Families and Child Wellbeing Study, and exploring a larger range of behavioral skills than previous literature, this paper provides estimates of the impact of paternal incarceration on children's behavioral functioning at age 9 using children's own self-reports. Comparisons to oft-used parent reports are made and heterogeneity by gender is explored. Findings suggest the incarceration of a father increases the antisocial behaviors children self-report, but has null effects on prosocial skill development. PMID:26004445

  16. Behavioral responses to and brain distribution of morphine in mature adult and aged mice

    SciTech Connect

    Burton, C.K.; Ho, I.K.; Hoskins, B.

    1986-03-01

    Mature adult (3-6 mo old) and aged (2 yr old) male ICR mice were injected with 10 to 100 mg/kg morphine, s.c. The ED50 values for running behavior (as measured using Stoelting activity monitors and having each mouse serve as its own control) representing 5 times control activity was approximately 7.5 mg/kg for aged mice and approximately 17.5 mg/kg for the mature adults. The ED50 values for analgesia 1 hr after morphine administration using the tail-flick method (max. response time = 8 sec) were approx. 70 mg/kg for the aged mice and 15 mg/kg for the mature adults. One hour after injecting /sup 3/H-morphine at doses of 30 and 100 mg/kg, 0.13 and 0.14% of the doses appeared in brains of aged and mature adult mice, respectively. Regional distribution of the morphine was the same for both age groups. Expressed as percent of total brain morphine, it was as follows: cortex, 30%; midbrain, 18%; cerebellum, 17%; medulla, 12%; pons, 9%; striatum, 8% and periaqueductal gray, 6%. Expressed as g morphine/g tissue for the 2 doses, the distribution was; periaqueductal gray, 30 and 80; striatum, 9 and 34; medulla, 6 and 20 pons; 5 and 19; cerebellum, 4 and 13; midbrain 2.5 and 8.5 and cortex, 2 and 8. These results suggest that the differences in response to morphine by the two age groups were due to age-related differences in opioid receptor populations and/or affinities.

  17. Determination of Constant Parameters of Copper as Power-Law Hardening Material at Different Test Conditions

    NASA Astrophysics Data System (ADS)

    Kowser, Md. A.; Mahiuddin, Md.

    2014-11-01

    In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, α . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu) has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, α from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve) can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp) manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering fields.

  18. The etiological moderation of aggressive and nonaggressive antisocial behavior by age.

    PubMed

    Burt, S Alexandra; Klump, Kelly L

    2009-08-01

    A recent study has suggested that aggressive (AGG) and non-aggressive, rule-breaking (RB) antisocial behavior evidence differential and subtype-specific patterns of genetic expression during development. Namely, although genetic influences on RB increase dramatically during early- to mid-adolescence, genetic influences on AGG appear to remain stable. As no other study has examined age-related change in AGG versus RB, more research is clearly needed before any firm conclusions can be drawn. The current study thus examined whether and how age impacted genetic and environmental influences on AGG and RB in a sample of 252 10- to 15-year-old twin pairs assessed as part of the Michigan State University Twin Registry (MSUTR). Results constructively replicated and extended prior findings, indicating that while the magnitude of genetic and environmental influences on AGG remained stable across adolescence, genetic influences on RB increased dramatically with age. Such findings provide additional support for etiological distinctions within the broader construct of antisocial behavior based on the presence or absence of aggression, and offer insights into the expression of genetic influences during development. PMID:19653834

  19. Age-of-Onset or Behavioral Sub-Types? A Prospective Comparison of Two Approaches to Characterizing the Heterogeneity within Antisocial Behavior

    ERIC Educational Resources Information Center

    Burt, S. Alexandra; Donnellan, M. Brent; Iacono, William G.; McGue, Matt

    2011-01-01

    There are two common approaches to sub-typing the well-documented heterogeneity within antisocial behavior: age-of-onset (i.e., childhood-onset versus adolescence-onset; see "Moffitt" 1993) and behavioral (i.e., physical aggression versus non-aggressive rule-breaking). These approaches appear to be associated, such that aggression is more…

  20. Incorporating the effect of orientation hardening in an effective temperature nonequilibrium theory for glassy polymers

    NASA Astrophysics Data System (ADS)

    Guo, Jingkai; Xiao, Rui; Nguyen, Thao

    Amorphous polymers exhibit a wide range of time and temperature dependent behavior. Recently, Xiao and Nguyen developed an effective temperature theory that can capture a wide variety of nonequilibrium behaviors at moderate strains. At large strains, the stress response of glassy polymers is dominated by strain hardening as a result of chain alignment. The goal of this study was to extend the effective temperature theory to large deformation and make it capable of modeling strain hardening from deformation-induced molecular alignment. We compared two approaches. In the spirit of internal state variable thermodynamics theory, we introduced a series of stretch-like internal state variables to characterize the molecular resistance to plastic flow associated with each inelastic mechanism. The dependence of free energy on the internal state variables naturally gives rise to a deformation dependent back stress. The flow rule and the evolution of effective temperatures were derived in a thermodynamically consistent manner. In the second approach, we introduced a steady-state limit in the evolution of the effective temperature characterizing the nonequilibrium structure of the material. Both approaches can well capture the experimentally measured phenomena of orientation hardening, including the development of deformation-induced anisotropy in the yield strength and hardening modulus, the Bauschinger effect, and differences in the hardening moduli in tension and compression of pre-oriented specimens.

  1. Aging and emotional memory: the co-occurrence of neurophysiological and behavioral positivity effects.

    PubMed

    Langeslag, Sandra J E; van Strien, Jan W

    2009-06-01

    The positivity effect is a trend for adults to increasingly process positive and/or decreasingly process negative information compared with other information with advancing age. The positivity effect has been observed with behavioral measures, such as in attention and memory tests, and with measures of neurophysiological activity, such as in amygdala activation and the late positive potential (LPP). In this study, it was investigated whether these behavioral and neurophysiological positivity effects co-occur. The electroencephalogram of younger (19-26 years) and older (65-82 years) adults was recorded while they encoded unpleasant, neutral, and pleasant pictures for retrieval in free and cued recall tests. Positivity effects occurred in the late LPP amplitude (700-1,000 ms) and in the free recall test, with negativity biases in younger adults and no biases in older adults. The occurrence of a valence bias in the LPP was substantially but nonsignificantly correlated with the occurrence of a similar valence bias in memory in the older adults. In conclusion, neurophysiological and behavioral positivity effects appear to co-occur, a finding that awaits expansion using different neurophysiological and behavioral measures. PMID:19485614

  2. Do sex and age affect strategic behavior and inequity aversion in children?

    PubMed

    Bueno-Guerra, Nereida; Leiva, David; Colell, Montserrat; Call, Josep

    2016-10-01

    The ultimatum game is commonly used to explore fairness in adults in bargaining situations. Although the changes in responses that occur during development have been investigated in children, the results have been mixed. Whereas some studies show that proposers offer more when they grow older, others indicate the opposite. Moreover, these studies are outcome-based and leave intentions out of the scene, although intentions play a relevant role in daily life. The mini-ultimatum game offers the opportunity to test both outcomes and intentions, but one major obstacle for accurately pinpointing developmental transitions in strategic behavior and inequity aversion so far has been the multiple confounds that have plagued previous studies, including different methods, small sample sizes, and reduced age differences. We administered an anonymous direct-method one-shot mini-ultimatum game to 478 6- and 10-year-old children. Strategic behavior was present at 10 years of age; older participants matched more accurately what responders would accept than younger participants. However, this was true only for older girls. No sex differences were detected in younger children. No age group seemed to consider the proposer's intentions given that the rejections of the default option were not significant across conditions. Both disadvantageous and advantageous inequity aversions were present in 6-year-olds. However, older children exhibited significantly more disadvantageous inequity aversion than younger children. This contrast made the pattern of rejection of 6-year-olds look more similar to the pattern of rejection found in adults. No sex differences were found in responders' behavior. PMID:27372561

  3. Effects of age on behavioral and physiological responses to carbaryl in rats.

    PubMed

    Takahashi, R N; Poli, A; Morato, G S; Lima, T C; Zanin, M

    1991-01-01

    Motor, sensory and thermoregulatory functions were examined in young (3 months) and mature (12 months) rats following PO administration of single low doses (10 and 50 mg/kg) of carbaryl, a carbamate insecticide, and these effects were related to blood cholinesterase activity. Carbaryl 50 mg/kg decreased the frequency of ambulation in the open-field arena within 30 min while it enhanced the duration of haloperidol-induced catalepsy in both young and mature rats. Administration of carbaryl also resulted in an increased nociceptive threshold to thermic stimuli mainly in mature rats. An age-related reduction in body temperature was observed at 30, 60 and 90 min after injection. Activity of blood cholinesterase was reduced in young and mature rats at 30 and 60 min following carbaryl exposure. These results indicate that carbaryl can induce an age-related impairment on some behavioral and autonomic functions in rats correlated to the inhibition of cholinesterase activity. PMID:1904531

  4. Effects of thermal aging on the mechanical behavior of F82H weldments

    NASA Astrophysics Data System (ADS)

    Alamo, A.; Castaing, A.; Fontes, A.; Wident, P.

    2000-12-01

    The objective of this work is to characterize the mechanical behavior of F82H weldments, which were produced by tungsten inert gas (TIG) and electron beam (EB) processes. Tensile and impact properties were determined for both types of welds in the as-received condition and after thermal aging for 10 000 h at 400°C and 550°C. The mechanical properties of TIG welds and their evolution during aging is quite similar in the base metal (BM). The main difference was given by the impact energy level (upper shelf energy (USE)) of TIG joints, which is about 60% of the BM. EB welds were delivered without post-weld heat treatment. Very scattered results were obtained, particularly for impact properties.

  5. Rapid eye movement sleep behavior disorder in adults younger than 50 years of age.

    PubMed

    Ju, Yo-El S

    2013-08-01

    Rapid eye movement (REM) sleep behavior disorder (RBD) occurring prior to age 50 is termed early-onset RBD. Early-onset RBD comprises a substantial minority of cases, and demonstrates the differences in demographics, comorbidities, and clinical considerations from previously described typical RBD with onset >50years. The world literature on RBD is reviewed with specific focus on features that distinguish early-onset RBD, including more gender parity, increased proportion of idiopathic cases, increased proportion of cases associated with narcolepsy, parasomnia overlap disorder, antidepressants, and possibly autoimmune disorders, and clinical presentation. PMID:23347910

  6. Adoptive and Nonadoptive Mother–Child Behavioral Interaction: A Comparative Study at 4 Years of Age

    PubMed Central

    Suwalsky, Joan T. D.; Padilla, Christina M.; Yuen, Cynthia X.; Horn, E. Parham; Bradley, Alexandra L.; Putnick, Diane L.; Bornstein, Marc H.

    2016-01-01

    Comparable samples of low-risk adopted and nonadopted children and mothers were observed during 3 tasks at age 4 years. Quality of mother-child interactions, child level of functioning in 4 domains, and maternal parenting satisfaction and social support were assessed. Adopted children were as competent as nonadopted children on measures of developmental functioning. Both groups of mothers expressed high satisfaction and support as parents. However, ratings of child, maternal, and dyadic behavior when interacting were all lower for adoptive dyads than for nonadoptive dyads, and adoptive dyads with boys accounted for the maternal and dyadic group differences. PMID:27134518

  7. Health behavior and urinary tract infection in college-aged women.

    PubMed

    Foxman, B; Chi, J W

    1990-01-01

    We conducted a case-control study to examine the associations between various behavioral risk factors and urinary tract infection among college-aged women. Cases were collected from a University Health Service, and were compared to Health Service controls and to a population-based control group. Sexual intercourse, diaphragm use, and urinating after sexual intercourse were each associated with urinary tract infection (UTI). The magnitude of the association of diaphragm use with UTI was reduced when urination habits around sexual intercourse were considered. PMID:2324774

  8. Interrogating the Aged Striatum: Robust Survival of Grafted Dopamine Neurons in Aging Rats Produces Inferior Behavioral Recovery and Evidence of Impaired Integration

    PubMed Central

    Collier, Timothy J.; O’Malley, Jennifer; Rademacher, David J.; Stancati, Jennifer A.; Sisson, Kellie A.; Sortwell, Caryl E.; Paumier, Katrina L.; Gebremedhin, Kibrom G.; Steece-Collier, Kathy

    2015-01-01

    Advanced age is the primary risk factor for Parkinson disease (PD). In PD patients and rodent models of PD, advanced age is associated with inferior symptomatic benefit following intrastriatal grafting of embryonic dopamine (DA) neurons, a pattern believed to result from decreased survival and reinnervation provided by grafted neurons in the aged host. To help understand the capacity of the aged, parkinsonian striatum to be remodeled with new DA terminals, we used a grafting model and examined whether increasing the number of grafted DA neurons in aged rats would translate to enhanced behavioral recovery. Young (3 mo), middle-aged (15 mo), and aged (22 mo) parkinsonian rats were grafted with proportionately increasing numbers of embryonic ventral mesencephalic (VM) cells to evaluate whether the limitations of the graft environment in subjects of advancing age can be offset by increased numbers of transplanted neurons. Despite robust survival of grafted neurons in aged rats, reinnervation of striatal neurons remained inferior and amelioration of levodopa-induced dyskinesias (LID) was delayed or absent. This study demonstrates that: 1) counter to previous evidence, under certain conditions the aged striatum can support robust survival of grafted DA neurons; and 2) unknown factors associated with the aged striatum result in inferior integration of graft and host, and continue to present obstacles to full therapeutic efficacy of DA cell-based therapy in this model of aging. PMID:25771169

  9. Modelling of the aging behavior of polyamide 12 powder during laser melting process

    NASA Astrophysics Data System (ADS)

    Drummer, Dietmar; Wudy, Katrin; Drexler, Maximilian

    2015-05-01

    Concerning individualization, the requirements to products have increased. Additive manufacturing technologies, such as selective laser melting allow manufacturing of complex parts without tools and forms. Due to this additive manufacturing processes comply, in opposite to conventional techniques, with these increased demands on processing technology. Due to the high temperature during processing, a degradation of the used plastic powder occurs. The non-molten material in the building chamber, the so-called partcake, can be removed after building from the finished component and reused for another process. To realize reproducible part properties refreshing of partcake powder with 30 up to 50 % virgin powder is necessary. However, these refreshing strategies lead to varying component properties due to an undefined aging state. Previous investigations on oven aged powder for selective laser melting showed for short periods of storage near the melting point thermally induced post condensation is the predominate aging effect. Due to post condensation the molecular weight and thus the viscosity increases. This paper focuses on the modeling of the post condensation process to define the aging state of polyamide 12 powder in laser melting process. Therefore the rheological behavior of PA 12 powder in dependency of time and temperature is investigated. Isothermal viscosity measurements are conducted in order to describe the post condensation reaction with a model. With knowledge of the kinetics of the post condensation reaction the state of aging can be predicted in a second step. Thus expected useful life of the powder can be calculated in dependency of the building chamber temperature. These results are then compared with viscosity values of defined aged PA 12 powder to validate the determined model.

  10. Effects of age and exposure to heavy particles on a behavioral measure of anxiety

    NASA Astrophysics Data System (ADS)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.; Carrihill-Knoll, K. L.; Carey, A.; Foster, B. C.

    On forthcoming exploratory class missions astronauts will be expected to function in novel and possibly dangerous environments This requirement may produce anticipatory fear or anxiety Previous research has shown that exposure to HZE particles such as those experienced on missions beyond the protection provided by the magnetic shield of the earth can affect the performance of the organism on a variety of tasks In addition research has shown that there is an interaction between age and exposure to heavy particles on a variety of behavioral tasks such that older organisms are more susceptible to the deleterious effects of irradiation Because there are changes in exploration-induced anxiety as a function of age it is possible that exposure to HZE particles will also affect a middle-aged astronaut s ability to respond appropriately in anxiety producing situations The present experiment utilized the elevated plus-maze to evaluate the effects of age and exposure to HZE particle radiation on anxiety Fischer-344 rats 2 7 12 and 16 months of age at the time of irradiation were exposed to 56 Fe particles 1 GeV n 0 25-2 00 Gy in the NASA Space Radiation Laboratory at Brookhaven National Laboratory Control rats at each age were not irradiated At the time of testing the rats were 3- 11- 13- and 20-months old respectively Anxiety was studied using an elevated plus-maze The maze is composed of four arms in the shape of a sign placed 90 cm above the floor Two of the arms are enclosed and two of the arms are open The amount of

  11. BDNF increases with behavioral enrichment and an antioxidant diet in the aged dog.

    PubMed

    Fahnestock, Margaret; Marchese, Monica; Head, Elizabeth; Pop, Viorela; Michalski, Bernadeta; Milgram, William N; Cotman, Carl W

    2012-03-01

    The aged canine (dog) is an excellent model for investigating the neurobiological changes that underlie cognitive impairment and neurodegeneration in humans, as canines and humans undergo similar pathological and behavioral changes with aging. Recent evidence indicates that a combination of environmental enrichment and antioxidant-fortified diet can be used to reduce the rate of age-dependent neuropathology and cognitive decline in aged dogs, although the mechanisms underlying these changes have not been established. We examined the hypothesis that an increase in levels of brain-derived neurotrophic factor (BDNF) is one of the factors underlying improvements in learning and memory. Old, cognitively impaired animals that did not receive any treatment showed a significant decrease in BDNF mRNA in the temporal cortex when compared with the young group. Animals receiving either an antioxidant diet or environmental enrichment displayed intermediate levels of BDNF mRNA. However, dogs receiving both an antioxidant diet and environmental enrichment showed increased levels of BDNF mRNA when compared with untreated aged dogs, approaching levels measured in young animals. BDNF receptor TrkB mRNA levels did not differ between groups. BDNF mRNA levels were positively correlated with improved cognitive performance and inversely correlated with cortical Aβ((1-42)) and Aβ((1-40)) levels. These findings suggest that environmental enrichment and antioxidant diet interact to maintain brain levels of BDNF, which may lead to improved cognitive performance. This is the first demonstration in a higher animal that nonpharmacological changes in lifestyle in advanced age can upregulate BDNF to levels approaching those in the young brain. PMID:20447733

  12. Comparison of the physical aging behavior of a colloidal glass after shear melting and concentration jumps.

    PubMed

    Peng, Xiaoguang; McKenna, Gregory B

    2014-11-01

    Colloidal systems are considered good models of molecular glasses and we further explore the range of validity of this paradigm using a thermosensitive core-shell particle dispersion to study the aging response of a colloidal glass subsequent to both shear-melting and temperature (concentration)-jump perturbations in the vicinity of the glass transition concentration or temperature. Sequential creep experiments were used to probe the different aging responses of the system. The colloidal glass displays aging behavior after both types of perturbation and our results indicate that this colloidal glass is similar to a molecular glass, in that shift rates are found to be below unity and to decrease towards zero as the glass temperature (or concentration) is approached as temperature increases. However, the kinetics of the aging in the two cases are different indicating that the structural changes induced by the mechanical perturbation are different from those induced by the temperature or concentration jump-similar to findings on mechanical rejuvenation of molecular glasses. We also find differences between the colloidal glass and molecular glasses: In the case of the colloidal glass the structural recovery or equilibration times do not diverge, while the mechanical relaxation times do. On the other hand, for the molecular glass, both times change very rapidly with decreasing temperature, apparently towards a distant point of divergence. PMID:25493722

  13. Weight status and bullying behaviors among Chinese school-aged children.

    PubMed

    Liu, Xiaoqun; Chen, Gui; Yan, Junxia; Luo, Jiayou

    2016-02-01

    This study was to examine the relationship between measured weight status and three experiences as victims, bullies and bully-victims. The participants were 10,587 Chinese school-aged students (girls: 5,527, boys: 5,060) who ranged in age from 7 to 18 years old. Height and weight were measured. Bullying behavior was obtained by one-to-one interview in 7-10 years older students and group-administered surveys in 11-18 years older students. The results showed that, obese girls were more likely to be victimized (OR=1.73, CI: 1.16-2.59) compared to normal students. For boys, obesity was not associated with victimization, but obese boys (OR=1.45, CI: 1.04-2.03), especially 7-13 years old boys (OR=1.98, CI: 1.35-2.90) were more likely to bully others; obese boys also were more likely to be victim/bullies (OR=1.67, CI: 1.05-2.64). Weight victimization in Chinese school-aged children is not as common as in the west countries, but obese girls clearly realize more victimization, and obese younger boys show obvious aggression. Related departments should provide specific intervention for school bullying according students' weight status, age and gender. PMID:26773898

  14. Alleviation of behavioral deficits in aged rodents following implantation of encapsulated GDNF-producing fibroblasts.

    PubMed

    Emerich, D F; Plone, M; Francis, J; Frydel, B R; Winn, S R; Lindner, M D

    1996-10-14

    following implantation into aged rats and may be useful for treating some of the behavioral consequences of aging or disorders characterized by dopaminergic hypofunction. PMID:8930314

  15. The Origins of Mental Toughness – Prosocial Behavior and Low Internalizing and Externalizing Problems at Age 5 Predict Higher Mental Toughness Scores at Age 14

    PubMed Central

    Sadeghi Bahmani, Dena; Hatzinger, Martin; Gerber, Markus; Lemola, Sakari; Clough, Peter J.; Perren, Sonja; von Klitzing, Kay; von Wyl, Agnes; Holsboer-Trachsler, Edith; Brand, Serge

    2016-01-01

    Background: The concept of mental toughness (MT) has gained increasing importance among groups other than elite athletes by virtue of its psychological importance and explanatory power for a broad range of health-related behaviors. However, no study has focused so far on the psychological origins of MT. Therefore, the aims of the present study were: to explore, to what extent the psychological profiles of preschoolers aged five were associated with both (1) MT scores and (2) sleep disturbances at age 14, and 3) to explore possible gender differences. Method: Nine years after their first assessment at age five (preschoolers), a total of 77 adolescents (mean age: 14.35 years; SD = 1.22; 42% females) took part in this follow-up study. At baseline, both parents and teachers completed the Strengths and Difficulties Questionnaire (SDQ), covering internalizing and externalizing problems, hyperactivity, negative peer relationships, and prosocial behavior. At follow-up, participants completed a booklet of questionnaires covering socio-demographic data, MT, and sleep disturbances. Results: Higher prosocial behavior, lower negative peer relationships, and lower internalizing and externalizing problems at age five, as rated by parents and teachers, were associated with self-reported higher MT and lower sleep disturbances at age 14. At age 14, and relative to males, females had lower MT scores and reported more sleep disturbances. Conclusion: The pattern of results suggests that MT traits during adolescence may have their origins in the pre-school years. PMID:27605919

  16. Influence of slip system hardening assumptions on modeling stress dependence of work hardening

    NASA Astrophysics Data System (ADS)

    Miller, Matthew; Dawson, Paul

    1997-11-01

    Due to the discrete directional nature of processes such as crystallographic slip, the orientation of slip planes relative to a fixed set of loading axes has a direct effect on the magnitude of the external load necessary to induce dislocation motion (yielding). The effect such geometric or textural hardening has on the macroscopic flow stress can be quantified in a polycrystal by the average Taylor factor M¯. Sources of resistance to dislocation motion such as interaction with dislocation structures, precipitates, and grain boundaries, contribute to the elevation of the critically resolved shear strength τcrss. In continuum slip polycrystal formulations, material hardening phenomena are reflected in the slip system hardness equations. Depending on the model, the hardening equations and the mean field assumption can both affect geometric hardening through texture evolution. In this paper, we examine continuum slip models and focus on how the slip system hardening model and the mean field assumption affect the stress-strain response. Texture results are also presented within the context of how the texture affects geometric hardening. We explore the effect of employing slip system hardnesses averaged over different size scales. We first compare a polycrystal simulation employing a single hardness per crystal to one using a latent hardening formulation producing distinct slip system hardnesses. We find little difference between the amplitude of the single hardness and a crystal-average of the latent hardening values. The geometric hardening is different due to the differences in the textures predicted by each model. We also find that due to the high degree of symmetry in an fcc crystal, macroscopic stress-strain predictions using simulations employing crystal- and aggregateaveraged hardnesses are nearly identical. We find this to be true for several different mean field assumptions. An aggregate-averaged hardness may be preferred in light of the difficulty

  17. Use of Medication Prescribed for Emotional or Behavioral Difficulties among Children Aged 6-17 Years in the United ...

    MedlinePlus

    ... months for emotional or behavioral difficulties varied by poverty level. Among children aged 6–17 years, a ... in families having income below 100% of the poverty level (9.2%) used prescribed medication for emotional ...

  18. Mechanical properties and microstructure of 6061 aluminum alloy severely deformed by ARB process and subsequently aged at low temperatures

    NASA Astrophysics Data System (ADS)

    Terada, Daisuke; Kaneda, Yoma; Horita, Zenji; Matsuda, Kenji; Hirosawa, Shoichi; Tsuji, Nobuhiro

    2014-08-01

    In order to clarify the aging behavior in ultrafine grained (UFG) Al alloys, a commercial Al-Mg-Si alloy was severely deformed by accumulative roll-bonding (ARB) process and subsequently aged at 100°C or 170°C. The age-hardening behavior and microstructure change during aging were investigated. At 170 °C, age-hardening was observed in solution treated (ST) specimens, but solution-treated and ARB-processed specimens were not hardened by aging. On the other hand, the hardness of the both ST specimen and ARB-processed specimen increased by aging at 100°C. From TEM observation, it was found that the ARB- processed specimen had an ultrafine lamellar boundary structure and the structure was kept during aging at 170°C and 100°C. In the ST specimen aged at 170°C, fine precipitates were observed within coarse grains. In the specimen ARB-processed and subsequently aged at 170°C, coarser precipitates were observed within ultrafine grains and on grain boundaries. It was considered that the reason why the hardness of the specimens ARB-processed and subsequently aged did not increase was coarsening of precipitates. In the specimens aged at 100°C, obvious precipitates were not observed, but clusters Mg and Si seemed to form during the aging, leading to the increase in the hardness of the specimen. From the results, it was suggested that aging at low temperatures could improve mechanical properties of Al alloys through combining grain refinement and precipitation hardening.

  19. Modeling of anisotropic hardening of sheet metals

    NASA Astrophysics Data System (ADS)

    Yoshida, Fusahito; Hamasaki, Hiroshi; Uemori, Takeshi

    2013-12-01

    To describe the evolution of anisotropy of sheet metals, in terms of both r-values and stresses, the present paper proposes anisotropic hardening models, where the shape of yield surface changes with increasing plastic strain. In this framework of modeling, any types of yield functions are able to be used. The evolution of anisotropy is expressed by updating the yield function as an interpolation between two yield functions defined at two different effective plastic strains. In this paper, two types of interpolation models, i.e., nonlinear interpolation model and piecewise interpolation model are presented. These models are validated by comparing the experimental data on 3003-O aluminum sheet (after Hu, Int J Plasticity 23, 620-639, 2007). To describe the Bauschinger effect, the combined anisotropic-kinematic hardening model is formulated based on Yoshida-Uemori kinematic hardening model.

  20. Relationships between regulatory temperament dimensions and self-regulatory behaviors at 4 and 6 months of age.

    PubMed

    Aureli, Tiziana; Coppola, Gabrielle; Picconi, Laura; Grazia, Annalisa; Ponzetti, Silvia

    2015-02-01

    The present study focused on relationships between temperament and behavior in early regulation development. Unlike most studies on the topic, we observed infant behavior in a naturalistic playful situation rather than in experimental stressful procedure, and employed temperament measures uniquely reflecting regulatory dispositions rather than a global measure of reactivity. The infant's self-regulatory behaviors were observed at 4 and 6 months during face-to-face interactions and regulatory dimensions were assessed at 4 months. We found that low intensity pleasure and soothability dimensions, related to the infant physical and social experience, respectively, significantly affected regulatory behavior and their influence showed to depend on the infant's age, with the former dimension being influential at the earlier age and the latter being influential when the behavior was observed at the later age. Results are interpreted on the light of a dynamic view of regulation development. PMID:25667170

  1. Fetal antiepileptic drug exposure: Adaptive and emotional/behavioral functioning at age 6years.

    PubMed

    Cohen, Morris J; Meador, Kimford J; Browning, Nancy; May, Ryan; Baker, Gus A; Clayton-Smith, Jill; Kalayjian, Laura A; Kanner, Andres; Liporace, Joyce D; Pennell, Page B; Privitera, Michael; Loring, David W

    2013-11-01

    The Neurodevelopmental Effects of Antiepileptic Drugs (NEAD) study is a prospective observational multicenter study in the USA and UK, which enrolled pregnant women with epilepsy on antiepileptic drug (AED) monotherapy from 1999 to 2004. The study aimed to determine if differential long-term neurodevelopmental effects exist across four commonly used AEDs (carbamazepine, lamotrigine, phenytoin, and valproate). In this report, we examine fetal AED exposure effects on adaptive and emotional/behavioral functioning at 6years of age in 195 children (including three sets of twins) whose parent (in most cases, the mother) completed at least one of the rating scales. Adjusted mean scores for the four AED groups were in the low average to average range for parent ratings of adaptive functioning on the Adaptive Behavior Assessment System-Second Edition (ABAS-II) and for parent and teacher ratings of emotional/behavioral functioning on the Behavior Assessment System for Children (BASC). However, children whose mothers took valproate during pregnancy had significantly lower General Adaptive Composite scores than the lamotrigine and phenytoin groups. Further, a significant dose-related performance decline in parental ratings of adaptive functioning was seen for both valproate and phenytoin. Children whose mothers took valproate were also rated by their parents as exhibiting significantly more atypical behaviors and inattention than those in the lamotrigine and phenytoin groups. Based upon BASC parent and teacher ratings of attention span and hyperactivity, children of mothers who took valproate during their pregnancy were at a significantly greater risk for a diagnosis of ADHD. The increased likelihood of difficulty with adaptive functioning and ADHD with fetal valproate exposure should be communicated to women with epilepsy who require antiepileptic medication. Finally, additional research is needed to confirm these findings in larger prospective study samples, examine

  2. Phenomenological modeling of hardening and thermal recovery in metals

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.

    1988-01-01

    Modeling of hardening and thermal recovery in metals is considered within the context of unified elastic-viscoplastic theories. Specifically, the choices of internal variables and hardening measures, and the resulting hardening response obtained by incorporating saturation-type evolution equations into two general forms of the flow law are examined. Based on the analytical considerations, a procedure for delineating directional and isotropic hardening from uniaxial hardening data has been developed for the Bodner-Partom model and applied to a nickel-base superalloy, B1900 + Hf. Predictions based on the directional hardening properties deduced from the monotonic loading data are shown to be in good agreement with results of cyclic tests.

  3. "Deviance Proneness" and Adolescent Smoking 1980 versus 2001: Has There Been a "Hardening" of Adolescent Smoking?

    ERIC Educational Resources Information Center

    Chassin, Laurie; Presson, Clark; Morgan-Lopez, Antonio; Sherman, Steven J.

    2007-01-01

    In a midwestern community sample, we tested for evidence of "hardening" of adolescent cigarette smoking between 1980 and 2001 by comparing adolescent smokers and nonsmokers at these two times on measures indicative of "deviance proneness" in Jessor and Jessor's [Jessor, R., & Jessor, S. L. (1977). "Problem behavior and psychosocial development: A…

  4. Thermoelastic constitutive equations for chemically hardening materials

    NASA Technical Reports Server (NTRS)

    Shaffer, B. W.; Levitsky, M.

    1974-01-01

    Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.

  5. 'Work-Hardenable' Ductile Bulk Metallic Glass

    SciTech Connect

    Das, Jayanta; Eckert, Juergen; Tang Meibo; Wang Weihua; Kim, Ki Buem; Baier, Falko; Theissmann, Ralf

    2005-05-27

    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<1%) at room temperature. We present a new class of bulk metallic glass, which exhibits high strength of up to 2265 MPa together with extensive 'work hardening' and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The 'work-hardening' capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.

  6. Radiation Hardened Electronics for Space Environments (RHESE)

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Adams, James H.; Frazier, Donald O.; Patrick, Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.

    2007-01-01

    Radiation Environmental Modeling is crucial to proper predictive modeling and electronic response to the radiation environment. When compared to on-orbit data, CREME96 has been shown to be inaccurate in predicting the radiation environment. The NEDD bases much of its radiation environment data on CREME96 output. Close coordination and partnership with DoD radiation-hardened efforts will result in leveraged - not duplicated or independently developed - technology capabilities of: a) Radiation-hardened, reconfigurable FPGA-based electronics; and b) High Performance Processors (NOT duplication or independent development).

  7. Maternal feeding practices and feeding behaviors of Australian children aged 12-36 months.

    PubMed

    Chan, L; Magarey, A M; Daniels, L A

    2011-11-01

    To explore parents' perceptions of the eating behaviors and related feeding practices of their young children. Mothers (N=740) of children aged 12-36 months and born in South Australia were randomly selected by birth date in four 6-month age bands from a centralized statewide database and invited to complete a postal questionnaire. Valid completed questionnaires were returned for 374 children (51% response rate; 54% female). Although mothers generally reported being confident and happy in feeding their children, 23% often worried that they gave their child the right amount of food. Based on a checklist of 36 specified items, 15% of children consumed no vegetables in the previous 24 h, 11% no fruit and for a further 8% juice was the only fruit. Of 12 specified high fat/sugar foods and drinks, 11% of children consumed none, 20% one, 26% two, and 43% three or more. Six of eight child-feeding practices that promote healthy eating behaviors were undertaken by 75% parents 'often' or 'all of the time'. However, 8 of 11 practices that do not promote healthy eating were undertaken by a third of mothers at least 'sometimes'. In this representative sample, dietary quality issues emerge early and inappropriate feeding practices are prevalent thus identifying the need for very early interventions that promote healthy food preferences and positive feeding practices. Such programs should focus not just on the 'what', but also the 'how' of early feeding, including the feeding relationship and processes appropriate to developmental stage. PMID:20872057

  8. Bullying behaviors among Chinese school-aged youth: a prevalence and correlates study in Guangdong Province.

    PubMed

    Wu, Jie; He, Yuan; Lu, Ciyong; Deng, Xueqing; Gao, Xue; Guo, Lan; Wu, Hong; Chan, Fanfan; Zhou, Ying

    2015-02-28

    Bullying among school-aged youth is a common issue worldwide and is increasingly being recognized as an important problem affecting both victims and perpetrators. Most of the bullying studies have been conducted in western countries, and their implications in other regions are limited due to different cultural contexts. The goal of our study is to identify the prevalence of bullying and its correlates school-aged youth in Guangdong province. In total, 1098 (7.1%) students reported having bullied other students, 744 (4.8%) students reported having been bullied by other students and 396 (2.6%) students reported having both bullied other students and been bullied by other students. There was a strong association between bullying others as well as being bullied and suicidal ideations, suicidal attempts, and self-harm behaviors. The prevalence of bullying and its associations with delinquent behaviors warrant the importance of school facility based preventive intervention taking into account both victims and perpetrators. PMID:25510905

  9. Effect of Aging Treatments on the Mechanical and Corrosive Behaviors of Spray-Formed 7075 Alloy

    NASA Astrophysics Data System (ADS)

    Su, Rui-ming; Qu, Ying-dong; Li, Rong-de

    2014-11-01

    Mechanical properties, microstructure, exfoliation corrosion (EXCO), and intergranular corrosion (IGC) behaviors of the spray-formed 7075 aluminum alloy after T6, T73, retrogression (R), and re-aging (RRA) treatment, respectively, were studied by using tensile tester, transmission electron microscope, and scanning electron microscope. The results show that the T6 process can increase the ultimate tensile strength (UTS) up to 760 MPa, while it decreases the elongation, the EXCO, and the IGC resistance of the alloy. The T73 process can improve elongation, the EXCO, and the IGC resistance of the alloy. The corrosion resistance of the alloy can also be improved by R and RRA processes with retrogression times increase. The tiny precipitated phases distributed homogeneously in the matrix can increase the UTS. The close-connected discrete grain boundary phases (GBP) and the narrow precipitate free zones (PFZ) will lower the elongation, the EXCO, and the IGC resistance of the alloy. Contrarily, the discrete GBP and wide PFZ can improve the elongation, the EXCO, and the IGC resistance of the alloy. The EXCO and the IGC behaviors for the spray-formed 7075 alloy after different aging treatments have been established according to the standards of ASTM G34-2001 (2007) and ASTM G110-1992 (2009).

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

    PubMed

    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. PMID:25270295

  11. Aging Behavior of the Viton® Fluoroelastomer O-Rings in the 9975 Shipping Package

    SciTech Connect

    Daugherty, W.; Mcwilliams, A.; Skidmore, E.

    2015-06-09

    The 9975 Type B shipping package is used within the DOE complex for shipping special nuclear materials. This package is re-certified annually in accordance with Safety Analysis Report requirements. The package is also used at the Savannah River Site as part of the long-term storage configuration of special nuclear materials. As such, the packages do not undergo annual recertification during storage, with uncertainty as to how long some of the package components will meet their functional requirements in the storage environment. The packages are currently approved for up to 15 years storage, and work continues to provide a technical basis to extend that period. This paper describes efforts by the Savannah River National Laboratory (SRNL) to extend the service life estimate of Viton® GLT and GLT-S fluoroelastomer O-rings used in the 9975 shipping package. O-rings of both compositions are undergoing accelerated aging at elevated temperature, and are periodically tested for compression stress relaxation (CSR) behavior and leak performance. The CSR behavior of O-rings was evaluated at temperatures from 79 °C to 177 °C. These collective data were used to develop predictive models for extrapolation of CSR behavior to relevant service temperatures (< 75 °C). O-rings were also aged in Primary Containment Vessel (PCV) fixtures at temperatures ranging from 79 °C to 232 °C. The fixtures are helium leak tested periodically to determine if they remain leak-tight. The PCV fixture tests demonstrate that the 9975 O-rings will remain leak-tight at temperatures up to 149 °C for 3 years or more, and no leak failures have been observed with up to 8 years aging at 93 °C. Significantly longer periods of leak-tight service are expected at the lower temperatures actually experienced in the storage environment. The predictive model developed from the CSR data conservatively indicates a service life of more than 20 years at the bounding temperature of 75 °C. Although the

  12. Caregiver behaviors and resources influence child height-for-age in rural Chad.

    PubMed

    Bégin, F; Frongillo, E A; Delisle, H

    1999-03-01

    The purpose of this study was to identify caregiver characteristics that influence child nutritional status in rural Chad, when controlling for socioeconomic factors. Variables were classified according to the categories of a UNICEF model of care: caregiving behaviors, household food security, food and economic resources and resources for care and health resources. Sixty-four households with 98 children from ages 12 to 71 mo were part of this study. Caregivers were interviewed to collect information on number of pregnancies, child feeding and health practices, influence on decisions regarding child health and feeding, overall satisfaction with life, social support, workload, income, use of income, and household food expenditures and consumption. Household heads were questioned about household food production and other economic resources. Caregiver and household variables were classified as two sets of variables, and separate regression models were run for each of the two sets. Significant predictors of height-for-age were then combined in the same regression model. Caregiver influence on child-feeding decisions, level of satisfaction with life, willingness to seek advice during child illnesses, and the number of individuals available to assist with domestic tasks were the caregiver factors associated with children's height-for-age. Socioeconomic factors associated with children's height-for-age were the amount of harvested cereals, the sources of household income and the household being monogamous. When the caregiver and household socioeconomic factors were combined in the same model, they explained 54% of the variance in children's height-for-age, and their regression coefficients did not change or only slightly increased, except for caregiver's propensity to seek advice during child illnesses, which was no longer significant. These results indicate that caregiver characteristics influence children's nutritional status, even while controlling for the socioeconomic

  13. Coming of age in an ant colony: cephalic muscle maturation accompanies behavioral development in Pheidole dentata

    NASA Astrophysics Data System (ADS)

    Muscedere, Mario L.; Traniello, James F. A.; Gronenberg, Wulfila

    2011-09-01

    Although several neurobiological and genetic correlates of aging and behavioral development have been identified in social insect workers, little is known about how other age-related physiological processes, such as muscle maturation, contribute to task performance. We examined post-eclosion growth of three major muscles of the head capsule in major and minor workers of the ant Pheidole dentata using workers of different ages with distinct task repertoires. Mandible closer muscle fibers, which provide bite force and are thus critical for the use of the mandibles for biting and load carrying, fill the posterio-lateral portions of the head capsule in mature, older workers of both subcastes. Mandible closer fibers of newly eclosed workers, in contrast, are significantly thinner in both subcastes and grow during at least the next 6 days in minor workers, suggesting this muscle has reduced functionality for a substantial period of adult life and thus constrains task performance capability. Fibers of the antennal muscles and the pharynx dilator, which control antennal movements and food intake, respectively, also increase significantly in thickness with age. However, these fibers are only slightly thinner in newly eclosed workers and attain their maximum thickness over a shorter time span in minors. The different growth rates of these functionally distinct muscles likely have consequences for how adult P. dentata workers, particularly minors, develop their full and diverse task repertoire as they age. Workers may be capable of feeding and interacting socially soon after eclosion, but require a longer period of development to effectively use their mandibles, which enable the efficient performance of tasks ranging from nursing to foraging and defense.

  14. Adaptive Behavior in Childhood as an Antecedent of Psychological Functioning in Early Middle Age: Linkage via Career Orientation

    ERIC Educational Resources Information Center

    Pulkkinen, Lea; Feldt, Taru; Kokko, Katja

    2006-01-01

    The main aim of the study was to investigate the link between child and adolescent adaptive behavior and adult psychological functioning, and the role of career orientation in this linkage. This was based on a Finnish longitudinal study, where data at ages 8, 14, and 42 were available for 118 females and 115 males. Adaptive behavior, indicated by…

  15. The Relation of Age, Gender, Ethnicity, and Risk Behaviors to Self-Esteem among Students in Nonmainstream Schools

    ERIC Educational Resources Information Center

    Connor, Jennifer M.; Poyrazli, Senel; Ferrer-Wreder, Laura; Grahame, Kamini Maraj

    2004-01-01

    This cross-sectional study investigated self-esteem in relation to age, gender, ethnicity, and risk behaviors among a sample of nonmainstream students. Participants were 149 students in the 6th to 12th grades from two non-mainstream schools (one charter and one alternative school). Self-esteem and youth risk behaviors were determined by using a…

  16. Causes of Age-Related Decline in Adaptive Behavior of Adults with Down Syndrome: Differential Diagnoses of Dementia.

    ERIC Educational Resources Information Center

    Prasher, V. P.; Chung, Man Cheung

    1996-01-01

    A study was conducted of 201 adults with Down's syndrome to investigate the differential causes of decline in adaptive behavior. Results indicated that aging, dementia, and severity of mental retardation were significant factors, while absence of a medical illness predicted a higher level of adaptive behavior. (CR)

  17. Peer Problems Mediate the Relationship between Developmental Coordination Disorder and Behavioral Problems in School-Aged Children

    ERIC Educational Resources Information Center

    Wagner, Matthias Oliver; Bos, Klaus; Jascenoka, Julia; Jekauc, Darko; Petermann, Franz

    2012-01-01

    The aim of this study was to gain insights into the relationship between developmental coordination disorder, peer problems, and behavioral problems in school-aged children where both internalizing and externalizing behavioral problems were considered. We assumed that the relationship between developmental coordination disorder and…

  18. Social Competence and Behavior Evaluation in Children Ages 3 to 6 Years: The Short Form (SCBE-30).

    ERIC Educational Resources Information Center

    LaFreniere, Peter J.; Dumas, Jean E.

    1996-01-01

    The factor structure and scale characteristics of a shortened version of the Social Competence and Behavior Evaluation Scale (SCBE) are presented for a Quebec (Canada) sample of 910 preschoolers and three U.S. samples totaling 1,736. Also presented are age and gender differences in preschool emotional and behavioral problems. (SLD)

  19. Sleep, Cognition, and Behavioral Problems in School-Age Children: A Century of Research Meta-Analyzed

    ERIC Educational Resources Information Center

    Astill, Rebecca G.; Van der Heijden, Kristiaan B.; Van IJzendoorn, Marinus H.; Van Someren, Eus J. W.

    2012-01-01

    Clear associations of sleep, cognitive performance, and behavioral problems have been demonstrated in meta-analyses of studies in adults. This meta-analysis is the first to systematically summarize all relevant studies reporting on sleep, cognition, and behavioral problems in healthy school-age children (5-12 years old) and incorporates 86 studies…

  20. Early Developmental and Psychosocial Risks and Longitudinal Behavioral Adjustment Outcomes for Preschool-Age Girls Adopted from China

    ERIC Educational Resources Information Center

    Tan, Tony Xing; Marfo, Kofi; Dedrick, Robert F.

    2010-01-01

    The central goal of this longitudinal study was to examine behavioral adjustment outcomes in a sample of preschool-age adopted Chinese girls. Research examining the effects of institutional deprivation on post-adoption behavioral outcomes for internationally adopted children has been constrained by the frequent unavailability of data on the…

  1. Health Behaviors and Protective Factors of School Students Aged 13-15 Years Old in Four Cities of China

    ERIC Educational Resources Information Center

    Tian, Benchun; Zhang, Wei; Qian, Ling; Lv, Shuhong; Tian, Xiangyang; Xiong, Guanglian; Yan, Weihong; Zhang, Xinwei; Kann, Laura K.; Riley, Leanne

    2007-01-01

    This paper presents baseline data on health behaviors and protective factors among junior middle school students aged 13-15 years old in China for the purpose of developing priorities, establishing programs and policies for school health and youth health and also establishing trends in the prevalence of these behaviors. The 2003 CHINA GSHS…

  2. Mothers' Parenting Behaviors in Families of School-Aged Children with Autism Spectrum Disorder: An Observational and Questionnaire Study

    ERIC Educational Resources Information Center

    Boonen, Hannah; van Esch, Lotte; Lambrechts, Greet; Maljaars, Jarymke; Zink, Inge; Van Leeuwen, Karla; Noens, Ilse

    2015-01-01

    Although parents of children with ASD face specific challenges in parenting, only a few studies have empirically investigated parenting behaviors among these parents. The current study examined differences in parenting behaviors between mothers of school-aged children with ASD (n = 30) and mothers of typically developing children (n = 39), using…

  3. Impact of Neonatal Growth on IQ and Behavior at Early School Age

    PubMed Central

    Lynch, John W.; Yang, Seungmi; Dahhou, Mourad; Kramer, Michael S.

    2013-01-01

    OBJECTIVES: The objective was to examine associations of neonatal weight gain (NWG) and head circumference gain (HCG) with IQ scores and behavior at early school age. METHODS: We used data from the Promotion of Breastfeeding Intervention Trial, involving Belarusian infants born full term and weighing ≥2500 g. NWG and HCG were measured as the percentage gain in weight and head circumference over the first 4 weeks relative to birth size. IQ and behavior were measured at 6.5 years of age by using the Wechsler Abbreviated Scales of Intelligence and the Strengths and Difficulties Questionnaire (SDQ), respectively, with SDQ collected from parents and teachers. The associations between the exposures (NWG, HCG) and children’s IQ and SDQ were examined by using mixed models to account for clustering of measurements, and adjustment for potentially confounding perinatal and socioeconomic factors. RESULTS: Mean NWG was 26% (SD 10%) of birth weight. In fully adjusted models, infants in the highest versus lowest quartile of NWG had 1.5-point (95% confidence interval [CI] 0.8 to 2.2) higher IQ scores (n = 13 840). A weak negative (protective) association between NWG and SDQ total difficulties scores was observed for the teacher-reported (β = −0.39, 95% CI −0.71 to −0.08, n = 12 016), but not the parent-reported (β = −0.12, 95% CI −0.39 to 0.15, n = 13 815), SDQ. Similar associations were observed with HCG and IQ and behavior. CONCLUSIONS: Faster gains in weight or head circumference in the 4 weeks after birth may contribute to children’s IQ, but reverse causality (brain function affects neonatal growth) cannot be excluded. PMID:23776123

  4. Diurnal Cortisol Pattern, Eating Behaviors and Overweight in Low-Income Preschool-Aged Children

    PubMed Central

    Lumeng, Julie C.; Miller, Alison L.; Peterson, Karen E.; Kaciroti, Niko; Sturza, Julie; Rosenblum, Katherine; Vazquez, Delia M.

    2014-01-01

    This study examined, among children, the associations among chaos in the home, diurnal cortisol patterns, eating behaviors and being overweight. Participants included 331 low-income children aged 3–4 years. Mean salivary cortisol-intercept (representing morning peak, 60 minutes since waking) and cortisol-slope (representing diurnal decline after peak) were calculated using mixed models from samples obtained across 3 days. Parents reported chaos in the home by questionnaire and responded to the Children’s Eating Behavior Questionnaire, generating subscales Food Responsiveness (FR), Emotional Overeating (EO), Enjoyment of Food (EF), and Satiety Responsiveness (SR). Body mass index was categorized as overweight versus not. Path analysis evaluated associations among chaos, cortisol patterns, eating behaviors, and weight status. Children living in more chaotic homes had lower morning cortisol levels, consistent with “hypocortisolism” reported among individuals who have experienced significant allostatic load as a result of substantial early life chronic stress. Among girls, the hypocortisolism pattern predicted a higher likelihood of being overweight both directly and mediated through reduced Satiety Responsiveness; in boys, the association of the hypocortisolism pattern with being overweight was mediated entirely through Emotional Overeating. In summary, our results provide support for the conceptual model that psychosocial stress contributes to hypocortisolism, which contributes directly to a higher likelihood of being overweight in girls, and indirectly through reduced Satiety Responsiveness in girls and through increased Emotional Overeating in boys. PMID:24177439

  5. Diurnal cortisol pattern, eating behaviors and overweight in low-income preschool-aged children.

    PubMed

    Lumeng, Julie C; Miller, Alison; Peterson, Karen E; Kaciroti, Niko; Sturza, Julie; Rosenblum, Katherine; Vazquez, Delia M

    2014-02-01

    This study examined, among children, the associations among chaos in the home, diurnal cortisol patterns, eating behaviors and being overweight. Participants included 331 low-income children aged 3-4years. Mean salivary cortisol-intercept (representing morning peak, 60min since waking) and cortisol-slope (representing diurnal decline after peak) were calculated using mixed models from samples obtained across 3days. Parents reported chaos in the home by questionnaire and responded to the Children's Eating Behavior Questionnaire, generating subscales Food Responsiveness (FR), Emotional Overeating (EO), Enjoyment of Food (EF), and Satiety Responsiveness (SR). Body mass index was categorized as overweight vs. not. Path analysis evaluated associations among chaos, cortisol patterns, eating behaviors, and weight status. Children living in more chaotic homes had lower morning cortisol levels, consistent with "hypocortisolism" reported among individuals who have experienced significant allostatic load as a result of substantial early life chronic stress. Among girls, the hypocortisolism pattern predicted a higher likelihood of being overweight both directly and mediated through reduced Satiety Responsiveness; in boys, the association of the hypocortisolism pattern with being overweight was mediated entirely through Emotional Overeating. In summary, our results provide support for the conceptual model that psychosocial stress contributes to hypocortisolism, which contributes directly to a higher likelihood of being overweight in girls, and indirectly through reduced Satiety Responsiveness in girls and through increased Emotional Overeating in boys. PMID:24177439

  6. Environmental impact to multimedia systems on the example of fingerprint aging behavior at crime scenes

    NASA Astrophysics Data System (ADS)

    Merkel, Ronny; Breuhan, Andy; Hildebrandt, Mario; Vielhauer, Claus; Bräutigam, Anja

    2012-06-01

    In the field of crime scene forensics, current methods of evidence collection, such as the acquisition of shoe-marks, tireimpressions, palm-prints or fingerprints are in most cases still performed in an analogue way. For example, fingerprints are captured by powdering and sticky tape lifting, ninhydrine bathing or cyanoacrylate fuming and subsequent photographing. Images of the evidence are then further processed by forensic experts. With the upcoming use of new multimedia systems for the digital capturing and processing of crime scene traces in forensics, higher resolutions can be achieved, leading to a much better quality of forensic images. Furthermore, the fast and mostly automated preprocessing of such data using digital signal processing techniques is an emerging field. Also, by the optical and non-destructive lifting of forensic evidence, traces are not destroyed and therefore can be re-captured, e.g. by creating time series of a trace, to extract its aging behavior and maybe determine the time the trace was left. However, such new methods and tools face different challenges, which need to be addressed before a practical application in the field. Based on the example of fingerprint age determination, which is an unresolved research challenge to forensic experts since decades, we evaluate the influences of different environmental conditions as well as different types of sweating and their implications to the capturing sensory, preprocessing methods and feature extraction. We use a Chromatic White Light (CWL) sensor to exemplary represent such a new optical and contactless measurement device and investigate the influence of 16 different environmental conditions, 8 different sweat types and 11 different preprocessing methods on the aging behavior of 48 fingerprint time series (2592 fingerprint scans in total). We show the challenges that arise for such new multimedia systems capturing and processing forensic evidence

  7. Trajectories of Adolescent Mother-Grandmother Psychological Conflict during Early Parenting and Children's Problem Behaviors at Age 7

    ERIC Educational Resources Information Center

    Buckingham-Howes, Stacy; Oberlander, Sarah E.; Hurley, Kristen M.; Fitzmaurice, Shannon; Black, Maureen M.

    2011-01-01

    This study extends the "determinants of parenting model" to adolescent mothers by examining how adolescent mother-grandmother psychological conflict and perceptions of infant fussiness from birth through age 2 years relate to children's problem behaviors at age 7. Participants were 181 adolescent mother, child, and grandmother triads living in…

  8. Spelling Difficulties in School-Aged Girls with Attention-Deficit/Hyperactivity Disorder: Behavioral, Psycholinguistic, Cognitive, and Graphomotor Correlates

    ERIC Educational Resources Information Center

    Åsberg Johnels, Jakob; Kopp, Svenny; Gillberg, Christopher

    2014-01-01

    Writing difficulties are common among children with attention-deficit/hyperactivity disorder (ADHD), but the nature of these difficulties has not been well studied. Here we relate behavioral, psycholinguistic, cognitive (memory/executive), and graphomotor measures to spelling skills in school-age girls with ADHD (n = 30) and an age-matched group…

  9. A prospective study of young females' sexual subjectivity: associations with age, sexual behavior, and dating.

    PubMed

    Zimmer-Gembeck, Melanie J; Ducat, Wendy H; Boislard-Pepin, Marie-Aude

    2011-10-01

    Sexual self-perceptions are important aspects of sexuality, which can undergo significant change during adolescence and early adulthood. The purpose of this study was to describe these changes among girls (N = 251; ages 16-25) over one year, and to examine associations of sexual self-perceptions (sexual subjectivity) with age, sexual behavior, and romantic status. Sexual body-esteem, perceptions of entitlement to desire and pleasure, sexual efficacy, and sexual self-reflection were investigated as elements of sexual subjectivity. All sexual subjectivity elements were higher among girls who had more sexual experience and/or had steady romantic partners during the study. Perception of entitlement to desire and pleasure increased over time, whereas sexual body-esteem showed the most stability and had minimal associations with sexual or romantic experiences. The greatest increases in sexual subjectivity were found among girls who began the study with the least sociosexual experience and self-reflection also increased for girls who had first coitus after the start of the study. Overall, girls who had sexual intercourse the earliest (before age 16) had the highest sexual subjectivity, but sexual subjectivity increased the most among girls without coital experience or who had more recent first coitus. PMID:21491139

  10. Tensile Behavior of Long-term Aged Nickel-base Superalloy

    NASA Astrophysics Data System (ADS)

    Xia, P. C.; Chen, F. W.; Xie, K.; Yu, J. J.

    2015-07-01

    The microstructural change of directionally solidified nickel-base superalloy which was aged at 900 °C for 1500 hours and tensile behavior at different temperatures were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). γ' phase of the alloy coarsens and rafts in the course of aged treatment. The driving force of rafting is the decrease of interface energy and elastic strain energy. The stress of aged alloy increases slightly with the testing temperature. This arises from a few dislocations shearing the γ' precipitates. There is a peak stress value at 760 °C, which is attributed to the high strength of the γ' phase, the homogeneous deformation structure, and dislocation-γ' precipitate and dislocation-dislocation interactions. The stress then decreases rapidly with increased temperature. The low stress of the γ' phase and γ' rafting at high temperature contribute to the drop of alloy strength. The change of elongation is inverse to that of the stress.

  11. Patterning and hardening of gold black infrared absorber by shadow mask deposition with ethyl cyanoacrylate

    NASA Astrophysics Data System (ADS)

    Panjwani, Deep; Nader-Esfahani, Nima; Maukonen, Doug; Rezadad, Imen; Boroumand, Javaneh; Smith, Evan; Nath, Janardan; Peale, R. E.

    2013-06-01

    Patterning of gold-black infrared absorbing films by stencil lithography and hardening by polymer infusion is reported. Gold black nano-structured films are deposited through a thin metal shadow mask in a thermal evaporator in ~400 mTorr pressure of inert gas, followed by ethyl cyanoacrylate fuming through the same mask to produce rugged IR absorptive patterns of ~100 micron scale dimensions. Infrared absorptivity is determined by transmission and reflectivity measurements using a Fourier spectrometer and infrared microscope. Results indicate that the optimized hardening process reduces the usual degradation of the absorptivity with age. This work has potential application to infrared array bolometers.

  12. A nonlinear kinematic hardening model for elastoplastic deformations in grey cast iron

    SciTech Connect

    Josefson, B.L.; Hjelm, H.E.; Stigh, U.

    1995-04-01

    A kinematic hardening model including an associated flow rule is proposed for elastoplastic deformations in graphitic grey cast iron. Quantitatively good results are obtained when comparing with previously performed biaxial experiments. Use of a nonassociated flow rule is found to result in an undesirable weakening behavior that can be explained as a deficiency with the combination of kinetic hardening and the present choice of yield potential. The model proposed is also extended to include multilinear kinematic hardening. With this model qualitatively good agreement with experimental cyclic results from the literature is obtained. A three-dimensional FE-analysis of a cylinder head for a heavy duty Diesel engine is performed as an application. To predict initiation of thermal fatigue cracks, it is essential to use an elastoplastic material model.

  13. Irradiation hardening of reduced activation martensitic steels

    NASA Astrophysics Data System (ADS)

    Kimura, A.; Morimura, T.; Narui, M.; Matsui, H.

    1996-10-01

    Irradiation response on the tensile properties of 9Cr2W steels has been investigated following FFTF/MOTA irradiations at temperatures between 646 and 873 K up to doses between 10 and 59 dpa. The largest irradiation hardening accompanied by the largest decrease in the elongation is observed for the specimens irradiated at 646 K at doses between 10 and 15 dpa. The irradiation hardening appears to saturate at a dose of around 10 dpa at the irradiation temperature. No hardening but softening was observed in the specimens irradiated at above 703 K to doses of 40 and 59 dpa. Microstructural observation by transmission electron microscope (TEM) revealed that the dislocation loops with the a<100> type Burgers vector and small precipitates which were identified to be M 6C type carbides existed after the irradiation at below 703 K. As for the void formation, the average size of voids increased with increasing irradiation temperature from 646 to 703 K. No voids were observed above 703 K. Irradiation softening was attributed to the enhanced recovery of martensitic structure under the irradiation. Post-irradiation annealing resulted in hardening by the annealing at 673 K and softening by the annealing at 873 K.

  14. SEU hardening of CMOS memory circuit

    NASA Technical Reports Server (NTRS)

    Whitaker, S.; Canaris, J.; Liu, K.

    1990-01-01

    This paper reports a design technique to harden CMOS memory circuits against Single Event Upset (SEU) in the space environment. A RAM cell and Flip Flop design are presented to demonstrate the method. The Flip Flop was used in the control circuitry for a Reed Solomon encoder designed for the Space Station.

  15. Extraordinary strain hardening by gradient structure

    PubMed Central

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T.

    2014-01-01

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures. PMID:24799688

  16. Behavioral Autonomy Age Expectations among Mexican-Origin Mother-Daughter Dyads: An Examination of Within-Group Variability

    PubMed Central

    Bámaca-Colbert, Mayra Y.; Umaña-Taylor, Adriana J.; Espinosa-Hernández, Graciela; Brown, Ashley M.

    2011-01-01

    This study examined differences in behavioral autonomy age expectations between Mexican-origin mothers and their adolescent daughters (N = 319 dyads); variability in behavioral autonomy age expectations as a function of nativity and maternal educational attainment also was examined. Findings indicated significant differences between mothers and daughters such that mothers reported later expectations for the timing of behavioral autonomy than did daughters. Follow-up analyses indicated that findings appeared to be driven by maternal nativity, with dyads comprised of Mexico-born mothers reporting the latest age expectations for behavioral autonomy when compared with dyads comprised of U.S.-born mothers. Findings underscore the need to examine normative development among Latino adolescents and their families with a specific focus on how sociocultural characteristics can contribute to within-family differences. PMID:22093152

  17. Does cyclic stress and accelerated ageing influence the wear behavior of highly crosslinked polyethylene?

    PubMed

    Affatato, Saverio; De Mattia, Jonathan Salvatore; Bracco, Pierangiola; Pavoni, Eleonora; Taddei, Paola

    2016-06-01

    First-generation (irradiated and remelted or annealed) and second-generation (irradiated and vitamin E blended or doped) highly crosslinked polyethylenes were introduced in the last decade to solve the problems of wear and osteolysis. In this study, the influence of the Vitamin-E addition on crosslinked polyethylene (XLPE_VE) was evaluated by comparing the in vitro wear behavior of crosslinked polyethylene (XLPE) versus Vitamin-E blended polyethylene XLPE and conventional ultra-high molecular weight polyethylene (STD_PE) acetabular cups, after accelerated ageing according to ASTM F2003-02 (70.0±0.1°C, pure oxygen at 5bar for 14 days). The test was performed using a hip joint simulator run for two millions cycles, under bovine calf serum as lubricant. Mass loss was found to decrease along the series XLPE_VE>STD_PE>XLPE, although no statistically significant differences were found between the mass losses of the three sets of cups. Micro-Raman spectroscopy was used to investigate at a molecular level the morphology changes induced by wear. The spectroscopic analyses showed that the accelerated ageing determined different wear mechanisms and molecular rearrangements during testing with regards to the changes in both the chain orientation and the distribution of the all-trans sequences within the orthorhombic, amorphous and third phases. The results of the present study showed that the addition of vitamin E was not effective to improve the gravimetric wear of PE after accelerated ageing. However, from a molecular point of view, the XLPE_VE acetabular cups tested after accelerated ageing appeared definitely less damaged than the STD_PE ones and comparable to XLPE samples. PMID:26970299

  18. Structural and functional connectivity in healthy aging: Associations for cognition and motor behavior.

    PubMed

    Hirsiger, Sarah; Koppelmans, Vincent; Mérillat, Susan; Liem, Franziskus; Erdeniz, Burak; Seidler, Rachael D; Jäncke, Lutz

    2016-03-01

    Age-related behavioral declines may be the result of deterioration of white matter tracts, affecting brain structural (SC) and functional connectivity (FC) during resting state. To date, it is not clear if the combination of SC and FC data could better predict cognitive/motor performance than each measure separately. We probed these relationships in the cingulum bundle, a major white matter pathway of the default mode network. We aimed to attain deeper knowledge about: (a) the relationship between age and the cingulum's SC and FC strength, (b) the association between SC and FC, and particularly (c) how the cingulum's SC and FC are related to cognitive/motor performance separately and combined. We examined these associations in a healthy and well-educated sample of 165 older participants (aged 64-85). SC and FC were acquired using probabilistic tractography to derive measures to capture white matter integrity within the cingulum bundle (fractional anisotropy, mean, axial and radial diffusivity) and a seed-based resting-state functional MRI correlation approach, respectively. Participants performed cognitive tests measuring processing speed, memory and executive functions, and motor tests measuring motor speed and grip force. Our data revealed that only SC but not resting state FC was significantly associated with age. Further, the cingulum's SC and FC showed no relation. Different relationships between cognitive/motor performance and SC/FC separately were found, but no additive effect of the combined analysis of cingulum's SC and FC for predicting cognitive/motor performance was apparent. Hum Brain Mapp 37:855-867, 2016. © 2015 Wiley Periodicals, Inc. PMID:26663386

  19. 'Fire hardening' spear wood does slightly harden it, but makes it much weaker and more brittle.

    PubMed

    Ennos, Antony Roland; Chan, Tak Lok

    2016-05-01

    It is usually assumed that 'fire hardening' the tips of spears, as practised by hunter-gatherers and early Homo spp., makes them harder and better suited for hunting. This suggestion was tested by subjecting coppiced poles of hazel to a fire-hardening process and comparing their mechanical properties to those of naturally seasoned poles. A Shore D hardness test showed that fire treatment slightly increased the hardness of the wood, but flexural and impact tests showed that it reduced the strength and work of fracture by 30% and 36%, respectively. These results suggest that though potentially slightly sharper and more durable, fire-hardened tips would actually be more likely to break off when used, as may have been the case with the earliest known wooden tool, the Clacton spear. Fire might first have been used to help sharpen the tips of spears, and fire-hardening would have been a mostly negative side effect, not its primary purpose. PMID:27194289

  20. A phenomenological model for bake hardening in minimal carbon steels

    NASA Astrophysics Data System (ADS)

    Das, Sourav; Nath Mohanty, Omkar; Brat Singh, Shiv

    2014-06-01

    The essence of bake hardening is to exploit the classical strain ageing in a positive way to increase the strength of the formed steel sheets used in outer body panel of a passenger car during the paint-baking operation. A new model that takes into account the strengthening contributions from Cottrell atmosphere and precipitate formation has been developed in the present work. The model predicts the increase in strength as a function of the amount of free solute C (calculated as a function of the annealing temperature), the amount of deformation, ageing temperature and time. The model predictions have been found to agree quite well with the experimental results; the individual contributions of Cottrell atmosphere and precipitation strengthening have been quantified.

  1. The influence of microstructure on the deformation behavior of beta solution heat treated and aged titanium aluminum tin zirconium molybdenum chromium silicate

    NASA Astrophysics Data System (ADS)

    Broderick, Thomas Froats

    to six characteristic crystallographic and morphological misorientations. Growth directions between pairs of alpha/beta variants were shown to have interface misorientations of (0°/180°), (24.9°/155.1°), (54.5°/125.5°), (60.76°/119.3°), (77.9°/102.1°) and (80.6°/99.4°). This information, combined with that in slip system misorientation diagrams, was used to make qualitative predictions of relative ease and difficulty of slip transmission between combinations of alpha/beta/alpha variants based on in-plane and out-of-plane misorientations of slip planes and slip directions. For example, slip transmission between variants of near parallel alignment (Delta = 1.38°) between (0001) and {10-11} with a common {011}<111> slip system was predicted, then confirmed through Transmission Electron Microscopy (TEM) imaging techniques. Six variations of the production "Triplex" Ti-62222S heat treatment process were developed and applied to effect large changes in room temperature tensile deformation behavior. Large changes in morphology of primary alpha features and the presence of alpha2-Ti3Al in the alpha promoted large reductions in fracture stress and fracture strain capability of beta solution heat-treated and aged Ti-62222S. These effects were shown to be additive, so that the combination of high amounts of aligned colony alpha + high presence of alpha2-Ti3Al in the alpha produced the lowest fracture stress and fracture strain. Work hardening in all six microstructures was relatively low, e.g. n ranging between ˜0.05 and 0.1. As with fracture behavior, increasing the amount of aligned or colony microstructure and/or increasing the presence of alpha2-Ti 3Al in the alpha were shown to lower work hardening. Examination of fracture surfaces and polished cross sections perpendicular to fracture surfaces revealed an associated transition from transgranular to intergranular fracture with increasing amount of aligned or colony alpha and if the final aging treatment

  2. Assessment of Cheating Behavior in Young School-Age Children: Distinguishing Normative Behaviors from Risk Markers of Externalizing Psychopathology

    ERIC Educational Resources Information Center

    Callender, Kevin A.; Olson, Sheryl L.; Kerr, David C. R.; Sameroff, Arnold J.

    2010-01-01

    The central goal of this longitudinal study was to develop a laboratory-based index of children's covert cheating behavior that distinguished normative rule violations from those that signal risk for antisocial behavior. Participants (N = 215 children) were drawn from a community population and oversampled for externalizing behavior problems…

  3. Multivariate Structure of Sexual Behaviors in Children: Associations with Age, Social Competence, Life Stressors, and Behavioral Disorders

    ERIC Educational Resources Information Center

    Santtila, Pekka; Sandnabba, Kenneth N.; Wannas, Malin; Krook, Katja

    2005-01-01

    The purpose of the present research was to explore the sexual behavior of children in Finnish daycare centers in order to identify subsets of homogeneous behaviors. The aim was also to explore effects of moderating factors, such as negative life events and behavioral disturbances, on the presence of variables within these subsets. A representative…

  4. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  5. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  6. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  7. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  8. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  9. From randomly accelerated particles to Lévy walks: non-ergodic behavior and aging

    NASA Astrophysics Data System (ADS)

    Radons, Guenter; Albers, Tony; Institute of Physics, Complex Systems; Nonlinear Dynamics Team

    For randomly accelerated particles we detected, and were able to analyze in detail (PRL 113, 184101 (2014)), the phenomenon of weak-ergodicity breaking (WEB), i.e. the inequivalence of ensemble- and time-averaged mean-squared displacements (MSD). These results, including their aging time dependence, are relevant for anomalous chaotic diffusion in Hamiltonian systems, for passive tracer transport in turbulent flows, and many other systems showing momentum diffusion. There are, however, several related models, such as the integrated random excursion model, or, space-time correlated Lévy walks and flights, with similar statistical behavior. We compare the WEB related properties of these models and find surprising differences although, for equivalent parameters, all of them are supposed to lead to the same ensemble-averaged MSD. Our findings are relevant for distinguishing possible models for the anomalous diffusion occurring in experimental situations.

  10. Behavioral and electrophysiological changes induced by acetyl-L-carnitine in aged freely-moving rats.

    PubMed

    Marini, G; Calvani, M; Ceccarelli, P; Mancia, M

    2006-02-01

    In chronically-implanted, drug-free, behaving aged Fischer rats, intracerebroventricularly (i.c.v.) and intraperitoneally (i.p.) acetyl-L-carnitine (ALCAR) injections powerfully enhanced motor behavior and head movements aimed at attention and exploratory activity. This effect was dose-dependent and associated with the abolition or substantial reduction of the incidence and duration of the spontaneous EEG generalized hypersynchronous patterns termed High Voltage Spindle (HVS), with an increase in EEG monitored theta activity. The results suggest that ALCAR may stimulate the motivational system and disrupt the hypersynchronous processes by inhibiting the GABAergic thalamic reticular neurons and/or activating the brain stem cholinergic reticular system (pedunculo pontine tegmental, PPT and laterodorsal tegmental, LDT nuclei). PMID:16425616

  11. Evaluation of the nucleation and coarsening kinetic behavior of the secondary hardening carbide of Fe-HCo-10Ni-1Mo-0.16C steel at two chromium levels, using an analytical and modeling approach: Part II

    NASA Astrophysics Data System (ADS)

    Oh, Y.; Machmeier, P. M.; Matuszewski, T.; Ayer, R.

    1997-06-01

    The effect of 1 % Cr addition on the resistivity during preaging and peak aging of an AF1410 based steel was examined by analytical and modeling approaches. The increased kinetics of aging resulting from a chromium addition, due to a variety of complex microstructural changes,was analyzed by Avrami-Mehl and Wert-Zener formulations, which were modified so that the exponent was a function of time. Using a eneralized Avrami equation, it was shown that the nucleation rate, N(t), at short aging times was large but became a rapidly declining function as N(t) approaches zero in a supersaturated system. A mathematical solution, using AF1410 steel carbide growth data at 510 °C, confirmed reported experimental evidence of second-stage carbide nucleation at 1 to 2 h.

  12. How are academic age, productivity and collaboration related to citing behavior of researchers?

    PubMed

    Milojević, Staša

    2012-01-01

    References are an essential component of research articles and therefore of scientific communication. In this study we investigate referencing (citing) behavior in five diverse fields (astronomy, mathematics, robotics, ecology and economics) based on 213,756 core journal articles. At the macro level we find: (a) a steady increase in the number of references per article over the period studied (50 years), which in some fields is due to a higher rate of usage, while in others reflects longer articles and (b) an increase in all fields in the fraction of older, foundational references since the 1980s, with no obvious change in citing patterns associated with the introduction of the Internet. At the meso level we explore current (2006-2010) referencing behavior of different categories of authors (21,562 total) within each field, based on their academic age, productivity and collaborative practices. Contrary to some previous findings and expectations we find that senior researchers use references at the same rate as their junior colleagues, with similar rates of re-citation (use of same references in multiple papers). High Modified Price Index (MPI, which measures the speed of the research front more accurately than the traditional Price Index) of senior authors indicates that their research has the similar cutting-edge aspect as that of their younger colleagues. In all fields both the productive researchers and especially those who collaborate more use a significantly lower fraction of foundational references and have much higher MPI and lower re-citation rates, i.e., they are the ones pushing the research front regardless of researcher age. This paper introduces improved bibliometric methods to measure the speed of the research front, disambiguate lead authors in co-authored papers and decouple measures of productivity and collaboration. PMID:23145111

  13. Effects of velvet antler polypeptide on sexual behavior and testosterone synthesis in aging male mice

    PubMed Central

    Zang, Zhi-Jun; Tang, Hong-Feng; Tuo, Ying; Xing, Wei-Jie; Ji, Su-Yun; Gao, Yong; Deng, Chun-Hua

    2016-01-01

    Twenty-four-month-old male C57BL/6 mice with low serum testosterone levels were used as a late-onset hypogonadism (LOH) animal model for examining the effects of velvet antler polypeptide (VAP) on sexual function and testosterone synthesis. These mice received VAP for 5 consecutive weeks by daily gavage at doses of 100, 200, or 300 mg kg−1 body weight per day (n = 10 mice per dose). Control animals (n = 10) received the same weight-based volume of vehicle. Sexual behavior and testosterone levels in serum and interstitial tissue of testis were measured after the last administration of VAP. Furthermore, to investigate the mechanisms of how VAP affects sexual behavior and testosterone synthesis in vivo, the expression of steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) in Leydig cells was also measured by immunofluorescence staining and quantitative real-time PCR. As a result, VAP produced a significant improvement in the sexual function of these aging male mice. Serum testosterone level and intratesticular testosterone (ITT) concentration also increased in the VAP-treated groups. The expression of StAR, P450scc, and 3β-HSD was also found to be enhanced in the VAP-treated groups compared with the control group. Our results suggested that VAP was effective in improving sexual function in aging male mice. The effect of velvet antler on sexual function was due to the increased expression of several rate-limiting enzymes of testosterone synthesis (StAR, P450scc, and 3β-HSD) and the following promotion of testosterone synthesis in vivo. PMID:26608944

  14. Effects of velvet antler polypeptide on sexual behavior and testosterone synthesis in aging male mice.

    PubMed

    Zang, Zhi-Jun; Tang, Hong-Feng; Tuo, Ying; Xing, Wei-Jie; Ji, Su-Yun; Gao, Yong; Deng, Chun-Hua

    2016-01-01

    Twenty-four-month-old male C57BL/6 mice with low serum testosterone levels were used as a late-onset hypogonadism (LOH) animal model for examining the effects of velvet antler polypeptide (VAP) on sexual function and testosterone synthesis. These mice received VAP for 5 consecutive weeks by daily gavage at doses of 100, 200, or 300 mg kg-1 body weight per day (n = 10 mice per dose). Control animals (n = 10) received the same weight-based volume of vehicle. Sexual behavior and testosterone levels in serum and interstitial tissue of testis were measured after the last administration of VAP. Furthermore, to investigate the mechanisms of how VAP affects sexual behavior and testosterone synthesis in vivo, the expression of steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) in Leydig cells was also measured by immunofluorescence staining and quantitative real-time PCR. As a result, VAP produced a significant improvement in the sexual function of these aging male mice. Serum testosterone level and intratesticular testosterone (ITT) concentration also increased in the VAP-treated groups. The expression of StAR, P450scc, and 3β-HSD was also found to be enhanced in the VAP-treated groups compared with the control group. Our results suggested that VAP was effective in improving sexual function in aging male mice. The effect of velvet antler on sexual function was due to the increased expression of several rate-limiting enzymes of testosterone synthesis (StAR, P450scc, and 3β-HSD) and the following promotion of testosterone synthesis in vivo. PMID:26608944

  15. How Are Academic Age, Productivity and Collaboration Related to Citing Behavior of Researchers?

    PubMed Central

    Milojević, Staša

    2012-01-01

    References are an essential component of research articles and therefore of scientific communication. In this study we investigate referencing (citing) behavior in five diverse fields (astronomy, mathematics, robotics, ecology and economics) based on 213,756 core journal articles. At the macro level we find: (a) a steady increase in the number of references per article over the period studied (50 years), which in some fields is due to a higher rate of usage, while in others reflects longer articles and (b) an increase in all fields in the fraction of older, foundational references since the 1980s, with no obvious change in citing patterns associated with the introduction of the Internet. At the meso level we explore current (2006–2010) referencing behavior of different categories of authors (21,562 total) within each field, based on their academic age, productivity and collaborative practices. Contrary to some previous findings and expectations we find that senior researchers use references at the same rate as their junior colleagues, with similar rates of re-citation (use of same references in multiple papers). High Modified Price Index (MPI, which measures the speed of the research front more accurately than the traditional Price Index) of senior authors indicates that their research has the similar cutting-edge aspect as that of their younger colleagues. In all fields both the productive researchers and especially those who collaborate more use a significantly lower fraction of foundational references and have much higher MPI and lower re-citation rates, i.e., they are the ones pushing the research front regardless of researcher age. This paper introduces improved bibliometric methods to measure the speed of the research front, disambiguate lead authors in co-authored papers and decouple measures of productivity and collaboration. PMID:23145111

  16. Investigation of the Influence Factors on Distortion in Induction-Hardened Steel Shafts Manufactured from Cold-Drawn Rod

    NASA Astrophysics Data System (ADS)

    Dong, Juan; Epp, Jeremy; Rocha, Alexandre da Silva; Nunes, Rafael Menezes; Zoch, Hans Werner

    2016-02-01

    In this study, the distortion of steel shafts was investigated before and after induction hardening. Several essential influencing factors in the manufacturing process chain regarding cold drawing, cutting method, notches on the shafts, and induction hardening were analyzed by design of experiment (DoE). Further necessary examinations of microstructures, hardness profile, segregation of chemical composition, and residual stress state were conducted for understanding the distortion behavior. The results of the statistical analysis of the DoE showed that the drawing process is the most important factor influencing distortion. The surface hardening depth of induction hardening is the second main factor. The relationship between inhomogeneities in the work pieces and the distortion was finally discussed.

  17. On constitutive relations at finite strain - Hypo-elasticity and elasto-plasticity with isotropic or kinematic hardening

    NASA Technical Reports Server (NTRS)

    Atluri, S. N.

    1984-01-01

    Nagtegaal and de Jong (1982) have studied stresses generated by simple finite shear in the case of elastic-plastic and rigid-plastic materials which exhibit anisotropic hardening. They reported that the shear stress is oscillatory in time. It was found that the occurrence of such an 'anomaly' is not restricted to anisotropic plasticity. Similar behavior in finite shear may result even in the case of hypoelasticity and classical isotropic hardening plasticity theory. The present investigation is concerned with the central problem of 'generalizing' with respect to the finite strain case, taking into account the constitutive relations of infinitesimal strain theories of classical plasticity with isotropic or kinematic hardening. The problem of hypoelasticity is also considered. It is shown that current controversies surrounding the choice of stress rate in the finite-strain generalizations of the constitutive relations and the anomalies surrounding kinematic hardening plasticity theory are easily resolvable.

  18. Physical activity, sedentary behaviors and dietary habits among Saudi adolescents relative to age, gender and region

    PubMed Central

    2011-01-01

    Background Few lifestyle factors have been simultaneously studied and reported for Saudi adolescents. Therefore, the purpose of the present study was to report on the prevalence of physical activity, sedentary behaviors and dietary habits among Saudi adolescents and to examine the interrelationships among these factors using representative samples drawn from three major cities in Saudi Arabia. Methods This school-based cross-sectional study was conducted during the years 2009-2010 in three cities: Al-Khobar, Jeddah and Riyadh. The participants were 2908 secondary-school males (1401) and females (1507) aged 14-19 years, randomly selected using a multistage stratified sampling technique. Measurements included weight, height, sedentary behaviors (TV viewing, playing video games and computer use), physical activity using a validated questionnaire and dietary habits. Results A very high proportion (84% for males and 91.2% for females) of Saudi adolescents spent more than 2 hours on screen time daily and almost half of the males and three-quarters of the females did not meet daily physical activity guidelines. The majority of adolescents did not have a daily intake of breakfast, fruit, vegetables and milk. Females were significantly (p < 0.05) more sedentary, much less physically active, especially with vigorous physical activity, and there were fewer days per week when they consumed breakfast, fruit, milk and diary products, sugar-sweetened drinks, fast foods and energy drinks than did males. However, the females' intake of French fries and potato chips, cakes and donuts, and candy and chocolate was significantly (p < 0.05) higher than the males'. Screen time was significantly (p < 0.05) correlated inversely with the intake of breakfast, vegetables and fruit. Physical activity had a significant (p < 0.05) positive relationship with fruit and vegetable intake but not with sedentary behaviors. Conclusions The high prevalence of sedentary behaviors, physical inactivity and

  19. Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers

    SciTech Connect

    Chisholm, Claire; Bei, Hongbin; Lowry, M. B.; Oh, Jason; Asif, S.A. Syed; Warren, O.; Shan, Zhiwei; George, Easo P; Minor, Andrew

    2012-01-01

    The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion hardening behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion hardening causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.

  20. Influence of homogenization and artificial aging heat treatments on corrosion behavior of Mg-Al alloys

    SciTech Connect

    Beldjoudi, T.; Fiaud, C.; Robbiola, L. . Lab. d'Etudes de la Corrosion)

    1993-09-01

    The influence of heat treatment on corrosion behavior of magnesium-aluminum (Mg-9Al) alloys was investigated by studying the electrochemical properties of Mg-9Al in the solution-treated (T4) and artificially aged (T6) conditions. The alloys' properties were compared to those of pure Mg, the intermetallic Mg[sub 17]Al[sub 12] phase, and different Mg-Al-based alloys (Mg-3Al, AZ91). The Mg-9Al alloy exhibited better corrosion resistance in the T6 condition than in the T4 condition because of the intermetallic Mg[sub 17]Al[sub 12] precipitates present n the T6 alloy. The mechanism responsible for this behavior was attributed to a more protective porous film on the T6 matrix alloy than on the T4 alloy. Addition of zinc did not modify these results. Localized corrosion testing showed the Mg-Al alloys were attacked preferentially in relation to magnesium silicide (Mg[sub 2]Si) precipitates which were characterized clearly using metallurgical examinations.

  1. Aging.

    PubMed

    Park, Dong Choon; Yeo, Seung Geun

    2013-09-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  2. Aging

    PubMed Central

    Park, Dong Choon

    2013-01-01

    Aging is initiated based on genetic and environmental factors that operate from the time of birth of organisms. Aging induces physiological phenomena such as reduction of cell counts, deterioration of tissue proteins, tissue atrophy, a decrease of the metabolic rate, reduction of body fluids, and calcium metabolism abnormalities, with final progression onto pathological aging. Despite the efforts from many researchers, the progression and the mechanisms of aging are not clearly understood yet. Therefore, the authors would like to introduce several theories which have gained attentions among the published theories up to date; genetic program theory, wear-and-tear theory, telomere theory, endocrine theory, DNA damage hypothesis, error catastrophe theory, the rate of living theory, mitochondrial theory, and free radical theory. Although there have been many studies that have tried to prevent aging and prolong life, here we introduce a couple of theories which have been proven more or less; food, exercise, and diet restriction. PMID:24653904

  3. Physiological and Behavioral Vulnerability Markers Increase Risk to Early Life Stress in Preschool-Aged Children.

    PubMed

    Kushner, Marissa R; Barrios, Chesley; Smith, Victoria C; Dougherty, Lea R

    2016-07-01

    The study examined whether child physiological (cortisol reactivity) and behavioral (negative emotionality) risk factors moderate associations between the early rearing environment, as measured by child exposure to maternal depression and stressful life events, and preschool psychopathology and psychosocial functioning. A sample of 156 preschool-aged children (77 boys, 79 girls; age M = 49.80 months, SD = 9.57, range: 36-71) participated in an observational assessment of temperament and was exposed to a stress-inducing laboratory task, during which we obtained five salivary cortisol samples. Parents completed clinical interviews to assess child and parent psychopathology and stressful life events. Results indicated that the combination of a blunted pattern of cortisol reactivity and recent stressful life events was associated with higher levels of preschoolers' externalizing symptoms and lower psychosocial functioning. In addition, greater life stress was associated with higher levels of preschoolers' internalizing symptoms. Lastly, children with high levels of negative emotionality and who were exposed to maternal depression had the lowest social competence. Our findings highlight the critical role of the early environment, particularly for children with identified risk factors, and add to our understanding of pathways involved in early emerging psychopathology and impairment. PMID:26424217

  4. Fish oil supplementation during lactation: effects on cognition and behavior at 7 years of age.

    PubMed

    Cheatham, Carol L; Nerhammer, Anne Sofie; Asserhøj, Marie; Michaelsen, Kim F; Lauritzen, Lotte

    2011-07-01

    Early accumulation of n-3 long-chain PUFA (LCPUFA) in the brain may contribute to differences in later cognitive abilities. In this study, our objective was to examine whether fish oil (FO) supplementation during lactation affects processing speed, working memory, inhibitory control, and socioemotional development at 7 years. Danish mothers (n = 122) were randomized to FO [1.5 g/d n-3 LCPUFA] or olive oil (OO) supplementation during the first 4 months of lactation. The trial also included a high-fish intake (HFI) reference group (n = 53). Ninety-eight children were followed-up with an assessment of processing speed, an age-appropriate Stroop task, and the Strength and Difficulties Questionnaire at 7 year. A group effect of the intervention (FO vs. OO) was found in prosocial behavior scores; this negative effect was carried by the boys. Exploratory analyses including all participants revealed the speed of processing scores were predicted by maternal n-3 LCPUFA intake during the intervention period (negative relation) and maternal education (positive relation). Stroop scores indicative of working memory and inhibitory control were predicted by infant erythrocyte DHA status at 4 months of age (negative relation). Early fish oil supplementation may have a negative effect on later cognitive abilities. Speed of processing and inhibitory control/working memory are differentially affected, with speed of processing showing effects of fish oil intake as a whole, whereas inhibitory control/working memory was related more specifically to DHA status. PMID:21512889

  5. Maternal Caffeine Intake During Pregnancy and Child Cognition and Behavior at 4 and 7 Years of Age.

    PubMed

    Klebanoff, Mark A; Keim, Sarah A

    2015-12-15

    Although caffeine is commonly consumed during pregnancy, there are few reports on the association of in utero caffeine exposure with offspring cognition or behavior during childhood. We evaluated the association of maternal serum paraxanthine, caffeine's primary metabolite, at <20 and ≥26 weeks' gestation with the child's intelligence quotient (IQ) and problem behaviors at ages 4 and 7 years among 2,197 mother-child pairs. The mothers were controls from a case-control study of caffeine metabolites and spontaneous abortion that was nested within the Collaborative Perinatal Project (multiple US sites, 1959-1974). Associations of paraxanthine (adjusted for maternal age, race, education, smoking, prepregnancy weight, gestational age at blood draw, and child sex) with mean IQ were assessed by linear regression and associations with problem behaviors by logistic regression. Paraxanthine concentration at ≥26 weeks' gestation manifested an inverted-J-shaped association with child's IQ at age 7 years, with a peak difference (vs. undetectable) of 0.65 points at 750 µg/L (66th percentile) and a decrement thereafter. Paraxanthine at <20 weeks was linearly associated with internalizing behavior at age 4 years (for a 500-µg/L increase, odds ratio = 1.3, 95% confidence interval: 1.1, 1.5). None of the remaining 12 associations approached statistical significance. We conclude that over a range of values applicable to most pregnant women, there was no meaningful association of serum paraxanthine level with childhood IQ or problem behaviors. PMID:26585526

  6. Learning ability in aged beagle dogs is preserved by behavioral enrichment and dietary fortification: a two-year longitudinal study.

    PubMed

    Milgram, N W; Head, E; Zicker, S C; Ikeda-Douglas, C J; Murphey, H; Muggenburg, B; Siwak, C; Tapp, D; Cotman, C W

    2005-01-01

    The effectiveness of two interventions, dietary fortification with antioxidants and a program of behavioral enrichment, was assessed in a longitudinal study of cognitive aging in beagle dogs. A baseline protocol of cognitive testing was used to select four cognitively equivalent groups: control food-control experience (C-C), control food-enriched experience (C-E), antioxidant fortified food-control experience (A-C), and antioxidant fortified food-enriched experience(A-E). We also included two groups of young behaviorally enriched dogs, one receiving the control food and the other the fortified food. Discrimination learning and reversal was assessed after one year of treatment with a size discrimination task, and again after two years with a black/white discrimination task. The four aged groups were comparable at baseline. At one and two years, the aged combined treatment group showed more accurate learning than the other aged groups. Discrimination learning was significantly improved by behavioral enrichment. Reversal learning was improved by both behavioral enrichment and dietary fortification. By contrast, the fortified food had no effect on the young dogs. These results suggest that behavioral enrichment or dietary fortification with antioxidants over a long-duration can slow age-dependent cognitive decline, and that the two treatments together are more effective than either alone in older dogs. PMID:15585348

  7. Effects of residual stress on irradiation hardening in stainless steels

    NASA Astrophysics Data System (ADS)

    Okubo, N.; Miwa, Y.; Kondo, K.; Kaji, Y.

    2009-04-01

    Effects of residual stress on irradiation hardening were studied in advance for predicting irradiation assisted stress corrosion cracking. The specimens of SUS316 and SUS316L with several % plastic strains, which correspond to weld residual stress, were prepared by bending and keeping deformation under irradiation. Ion irradiations of 12 MeV Ni 3+ were performed at 330, 400 and 550 oC to 45 dpa. No bended specimen was simultaneously irradiated with the bended specimen. The residual stress was estimated by X-ray residual stress measurements before and after the irradiation. The micro-hardness was measured by using nanoindenter. The residual stress did not relax even for the case of the higher temperature aging at 500 oC for the same time of irradiation. The residual stress after ion irradiation up to high dpa, however, relaxed at these experimental temperatures. The irradiation hardening of stressed specimen was obviously lower than that of un-stressed one in case of SUS316L irradiated at 300 oC to 12 dpa.

  8. Behaviorally Activated mRNA Expression Profiles Produce Signatures of Learning and Enhanced Inhibition in Aged Rats with Preserved Memory

    PubMed Central

    Haberman, Rebecca P.; Colantuoni, Carlo; Koh, Ming Teng; Gallagher, Michela

    2013-01-01

    Aging is often associated with cognitive decline, but many elderly individuals maintain a high level of function throughout life. Here we studied outbred rats, which also exhibit individual differences across a spectrum of outcomes that includes both preserved and impaired spatial memory. Previous work in this model identified the CA3 subfield of the hippocampus as a region critically affected by age and integral to differing cognitive outcomes. Earlier microarray profiling revealed distinct gene expression profiles in the CA3 region, under basal conditions, for aged rats with intact memory and those with impairment. Because prominent age-related deficits within the CA3 occur during neural encoding of new information, here we used microarray analysis to gain a broad perspective of the aged CA3 transcriptome under activated conditions. Behaviorally-induced CA3 expression profiles differentiated aged rats with intact memory from those with impaired memory. In the activated profile, we observed substantial numbers of genes (greater than 1000) exhibiting increased expression in aged unimpaired rats relative to aged impaired, including many involved in synaptic plasticity and memory mechanisms. This unimpaired aged profile also overlapped significantly with a learning induced gene profile previously acquired in young adults. Alongside the increased transcripts common to both young learning and aged rats with preserved memory, many transcripts behaviorally-activated in the current study had previously been identified as repressed in the aged unimpaired phenotype in basal expression. A further distinct feature of the activated profile of aged rats with intact memory is the increased expression of an ensemble of genes involved in inhibitory synapse function, which could control the phenotype of neural hyperexcitability found in the CA3 region of aged impaired rats. These data support the conclusion that aged subjects with preserved memory recruit adaptive mechanisms to

  9. Behaviorally activated mRNA expression profiles produce signatures of learning and enhanced inhibition in aged rats with preserved memory.

    PubMed

    Haberman, Rebecca P; Colantuoni, Carlo; Koh, Ming Teng; Gallagher, Michela

    2013-01-01

    Aging is often associated with cognitive decline, but many elderly individuals maintain a high level of function throughout life. Here we studied outbred rats, which also exhibit individual differences across a spectrum of outcomes that includes both preserved and impaired spatial memory. Previous work in this model identified the CA3 subfield of the hippocampus as a region critically affected by age and integral to differing cognitive outcomes. Earlier microarray profiling revealed distinct gene expression profiles in the CA3 region, under basal conditions, for aged rats with intact memory and those with impairment. Because prominent age-related deficits within the CA3 occur during neural encoding of new information, here we used microarray analysis to gain a broad perspective of the aged CA3 transcriptome under activated conditions. Behaviorally-induced CA3 expression profiles differentiated aged rats with intact memory from those with impaired memory. In the activated profile, we observed substantial numbers of genes (greater than 1000) exhibiting increased expression in aged unimpaired rats relative to aged impaired, including many involved in synaptic plasticity and memory mechanisms. This unimpaired aged profile also overlapped significantly with a learning induced gene profile previously acquired in young adults. Alongside the increased transcripts common to both young learning and aged rats with preserved memory, many transcripts behaviorally-activated in the current study had previously been identified as repressed in the aged unimpaired phenotype in basal expression. A further distinct feature of the activated profile of aged rats with intact memory is the increased expression of an ensemble of genes involved in inhibitory synapse function, which could control the phenotype of neural hyperexcitability found in the CA3 region of aged impaired rats. These data support the conclusion that aged subjects with preserved memory recruit adaptive mechanisms to

  10. Resting heart rate and the development of antisocial behavior from age 9 to 14: genetic and environmental influences.

    PubMed

    Baker, Laura A; Tuvblad, Catherine; Reynolds, Chandra; Zheng, Mo; Lozano, Dora Isabel; Raine, Adrian

    2009-01-01

    The genetic and environmental basis of a well-replicated association between antisocial behavior (ASB) and resting heart rate was investigated in a longitudinal twin study, based on two measurements between the ages of 9 and 14 years. ASB was defined as a broad continuum of externalizing behavior problems, assessed at each occasion through a composite measure based on parent ratings of trait aggression, delinquent behaviors, and psychopathic traits in their children. Parent ratings of ASB significantly decreased across age from childhood to early adolescence, although latent growth models indicated significant variation and twin similarity in the growth patterns, which were explained almost entirely by genetic influences. Resting heart rate at age 9-10 years old was inversely related to levels of ASB but not change patterns of ASB across age or occasions. Biometrical analyses indicated significant genetic influences on heart rate during childhood, as well as ASB throughout development from age 9 to 14. Both level and slope variation were significantly influenced by genetic factors. Of importance, the low resting heart rate and ASB association was significantly and entirely explained by their genetic covariation, although the heritable component of heart rate explained only a small portion (1-4%) of the substantial genetic variance in ASB. Although the effect size is small, children with low resting heart rate appear to be genetically predisposed toward externalizing behavior problems as early as age 9 years old. PMID:19583891

  11. Walking in School-Aged Children in a Dual-Task Paradigm Is Related to Age But Not to Cognition, Motor Behavior, Injuries, or Psychosocial Functioning

    PubMed Central

    Hagmann-von Arx, Priska; Manicolo, Olivia; Lemola, Sakari; Grob, Alexander

    2016-01-01

    Age-dependent gait characteristics and associations with cognition, motor behavior, injuries, and psychosocial functioning were investigated in 138 typically developing children aged 6.7–13.2 years (M = 10.0 years). Gait velocity, normalized velocity, and variability were measured using the walkway system GAITRite without an additional task (single task) and while performing a motor or cognitive task (dual task). Assessment of children’s cognition included tests for intelligence and executive functions; parents reported on their child’s motor behavior, injuries, and psychosocial functioning. Gait variability (an index of gait regularity) decreased with increasing age in both single- and dual-task walking. Dual-task gait decrements were stronger when children walked in the motor compared to the cognitive dual-task condition and decreased with increasing age in both dual-task conditions. Gait alterations from single- to dual-task conditions were not related to children’s cognition, motor behavior, injuries, or psychosocial functioning. PMID:27014158

  12. Effectiveness of hardening threaded parts by plastic deformation

    SciTech Connect

    Pyshkin, V.A.; Belai, S.V.; Dyad'kova, I.G.

    1983-03-01

    The rules of hardening threaded parts by roller burning the root of the inner diameter of a thread are studied. The effectiveness of hardening increases where the allowance for the inner diameter increases. By equations, a change in the inner diameter can be used to determine the depth of work hardening residual compressive stress, fatigue limit, and the mechanical properties of the threaded part. The effective stress concentration factor, increase in transmission load, and average tensile stress in cyclic loading, are also calculated. Equations help to determine the depth of hardening necessary; the optimum conditions of burnishing; and the maximum increase in fatigue strength, with optimum hardening conditions.

  13. Finite-Element Simulation of Conventional and High-Speed Peripheral Milling of Hardened Mold Steel

    NASA Astrophysics Data System (ADS)

    Tang, D. W.; Wang, C. Y.; Hu, Y. N.; Song, Y. X.

    2009-12-01

    A finite-element model (FEM) with the flow stress and typical fracture is used to simulate a hard machining process, which before this work could not adequately represent the constitutive behavior of workpiece material that is usually heat treated to hardness levels above 50 Rockwell C hardness (HRC). Thus, a flow stress equation with a variation in hardness is used in the computer simulation of hard machining. In this article, the influence of the milling speed on the cutting force, chip morphology, effective stress, and cutting temperature in the deformation zones of both conventional and high-speed peripheral milling hardened mold steel is systematically studied by finite-element analysis (FEA). By taking into consideration the importance of material characteristics during the milling process, the similar Johnson-Cook’s constitutive equation with hardened mold steel is introduced to the FEM to investigate the peripheral milling of hardened mold steel. In comparison with the experimental data of the cutting force at various cutting speeds, the simulation result is identical with the measured data. The results indicate that the model can be used to accurately predict the behavior of hardened mold steel in both conventional and high-speed milling.

  14. Construction procedures using self hardening fly ash

    NASA Astrophysics Data System (ADS)

    Thornton, S. I.; Parker, D. G.

    1980-07-01

    Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

  15. Modeling the Case Hardening of Automotive Components

    NASA Astrophysics Data System (ADS)

    Munikamal, Tiruttani; Sundarraj, Suresh

    2013-04-01

    A generalized framework has been developed within ABAQUS to model the surface hardening heat treatment processes for automotive steel components. The macro-scale heat transfer and stress calculations during the heating and quenching are coupled with the microstructural phase calculations, defined through a user routine, to estimate key process parameters such as case depth and surface hardness. This model has been applied to predict these parameters in two key industrial processes, i.e., case hardening of crankshafts and case carburization of gears. The results of the case depth and hardness calculations have been validated with the literature and in-house plant data. The effect of varying quench conditions on the overall stress distribution changes within the component has been outlined.

  16. Radiation-hardened transistor and integrated circuit

    DOEpatents

    Ma, Kwok K.

    2007-11-20

    A composite transistor is disclosed for use in radiation hardening a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation harden the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.

  17. Work hardening: occupational therapy in industrial rehabilitation.

    PubMed

    Matheson, L N; Ogden, L D; Violette, K; Schultz, K

    1985-05-01

    Work hardening, presented in this paper as a "new" service for the industrially injured, is actually well grounded in the traditional models and practices of occupational therapy. From the profession's early roots in industrial therapy to the development of a variety of programs for the industrially injured through the 1950s and 1960s, the historical and philosophical bases of occupational therapy support the use of work as an evaluative and therapeutic medium. What is actually new is the adoption of terminology, technology, and a program format that fits in with the needs of consumers in the 1980s. Recent developments that created the need for the specialized services that occupational therapists are uniquely qualified to provide include growth of private sector vocational rehabilitation, changes in workers' compensation laws, and increasing costs of vocational rehabilitation. This paper describes work hardening in its present form. A case example is given that demonstrates how work hardening can be a cost-effective and time-saving bridge which spans the gap between curative medicine and the return to work. PMID:4014411

  18. Dislocation Multi-junctions and Strain Hardening

    SciTech Connect

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T

    2006-06-20

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  19. Pulsed laser surface hardening of ferrous alloys.

    SciTech Connect

    Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

    1999-09-30

    A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

  20. The influence of persistent crowding on the age changes of behavioral parameters and survival characteristics of rats.

    PubMed

    Skalicky, M; Bubna-Littitz, H; Hofecker, G

    1984-12-01

    One hundred fifty-six male Sprague-Dawley rats were submitted to crowding (12 rats/Makrolon-IV cage) from an age of 5 months onwards. An equal number from the same age cohort served as a control (6 rats/Makrolon-IV cage). As part of an age-test program, behavioral parameters (spontaneous motor activity, reactive motor activity and maze-learning ability) were measured at various ages between 8 and 30 months. The rats were sacrificed for additional measurements after the behavioral tests. Survival curves and age-specific mortality rates were calculated for those rats which died spontaneously in the course of the study. Control rats showed a significant decrease in spontaneous motor activity after an age of 18 months. Reactive motor activity of the controls revealed a fall in the number of large movements between 9 and 15 months, whereas the number of small movements increased up to an age of 30 months. Crowding conditions increased significantly both spontaneous and reactive activity. Maze-learning ability declined significantly with age in the controls whereas crowded rats revealed a tendency to better performance which seemed to be submitted to a seasonal rhythm. Crowded rats showed an improved survival characteristic, beginning at an age of 700 days. Mortality curves turned out to be distinct and parallel by straight line regression. It has been concluded that the positive effects of crowding on behavioral parameters and survival could be attributed to a decrease in vulnerability rather than to a lowered rate of aging. PMID:6521513

  1. Social network analysis - centrality parameters and individual network positions of agonistic behavior in pigs over three different age levels.

    PubMed

    Büttner, Kathrin; Scheffler, Katharina; Czycholl, Irena; Krieter, Joachim

    2015-01-01

    Knowledge of the network structure of agonistic interactions helps to understand the formation and the development of aggressive behavior. Therefore, video observation data of 149 pigs over three different age levels were investigated for 2 days each directly after mixing (65 groups in the rearing area, 24 groups in the growing stable and 12 groups in the breeding stable). The aim of the study was to use network analysis to investigate the development of individual network positions of specific animals and to determine whether centrality parameters in previous mixing situations have an impact on the future behavior of the animals. The results of the weighted degree centrality indicated that weaned pigs had a higher fighting intensity directly after mixing compared to growing pigs and gilts. Also, the number of different opponents (degree centrality) was higher compared to the older age groups. The betweenness centrality showed relatively small values and no significant differences between the different age levels, whereas the closeness centrality showed high values at all observed age levels. Experiences gained in previous agonistic interactions had an impact on the centrality parameters in subsequent mixing situations. It was shown that the position of individual animals in agonistic interaction networks can be characterized using social network analysis and that changes over different age levels can be detected. Therefore, social network analysis provides insights into the formation and evolution of behavioral patterns which could be of particular interest for the identification of key factors with regard to abnormal behavior (e.g. tail biting). PMID:25932371

  2. Spontaneous failure of the estrous cycle induces anxiogenic-related behaviors in middle-aged female mice.

    PubMed

    Guimarães, Rebecca A M; Asth, Laila; Engelberth, Rovena C; Cavalcante, Jeferson de Souza; Soares-Rachetti, Vanessa de Paula; Gavioli, Elaine C

    2015-08-01

    Clinical studies have shown that women during perimenopause and menopause have a higher incidence in the diagnoses of psychiatric problems compared with men. However, little literature information about the influence of spontaneous perimenopause on anxiety- and mood-related behaviors in mice is available. To this aim, we compared the behavioral responses of middle-aged and young adult female mice both in the diestrus phase in the elevated plus-maze, open field and forced swimming tests. In middle-aged mice, the duration of the estrous cycle was significantly prolonged compared to young adults, thus indicating that our middle-aged mice are in the perimenopausal period. In the elevated plus-maze test, middle-aged mice explored less the open arms when compared to young adults, suggesting an anxiogenic-like phenotype. No significant differences were observed in the estrogen plasma levels and emotional behavior in the forced swim and open field tests. In conclusion, the spontaneous failure of the estrous cycle increased anxiety in middle-aged females. These data suggest that the perimenopausal period has a significant influence on anxiety-related behaviors in female mice. PMID:25980629

  3. Maternal infection during late pregnancy increases anxiety- and depression-like behaviors with increasing age in male offspring.

    PubMed

    Enayati, Mohsen; Solati, Jalal; Hosseini, Mohammad-Hassan; Shahi, Hamid-Reza; Saki, Golshid; Salari, Ali-Akbar

    2012-02-10

    Scientific reports suggest that the exposure to long-term stressors throughout or during late gestation increase anxiety- and depression-like behaviors of offspring in their later life. Moreover, several studies concluded that increasing age correlates with increased anxiety behaviors in humans and rodents. In the present study, we assessed the effects of prenatally administration of equal lipopolysaccharide (LPS) doses in various points of late gestation (days 15, 16, and 17) period, on neuroendocrine and immunological responses of pregnant mice, and subsequent long-lasting consequences of anxiety and depression with increasing age in male offspring at postnatal days (PD) 40 and 80. Four hours after the LPS injection, levels of corticosterone (COR) and pro-inflammatory cytokines (PIC) in pregnant mice, as compared to the control dams, were increased significantly. Furthermore, maternal inflammation raised the levels of COR, anxiety- and depression-like behaviors with increasing age in male offspring in comparison with saline male offspring. These data support other studies demonstrating that maternal stress increases the levels of anxiety and depression in offspring. Additionally, our data confirm other findings indicating that increasing age correlates with increased anxiety or depression behaviors in humans and rodents. Findings of this study suggest that time course of an inflammation response or stressor application during various stages of gestation and ages of offspring are important factors for assessing neuropsychiatric disorders. PMID:21893170

  4. Individual Differences in Exercise Behavior: Stability and Change in Genetic and Environmental Determinants From Age 7 to 18.

    PubMed

    Huppertz, Charlotte; Bartels, Meike; de Zeeuw, Eveline L; van Beijsterveldt, Catharina E M; Hudziak, James J; Willemsen, Gonneke; Boomsma, Dorret I; de Geus, Eco J C

    2016-09-01

    Exercise behavior during leisure time is a major source of health-promoting physical activity and moderately tracks across childhood and adolescence. This study aims to investigate the absolute and relative contribution of genes and the environment to variance in exercise behavior from age 7 to 18, and to elucidate the stability and change of genetic and shared environmental factors that underlie this behavior. The Netherlands Twin Register collected data on exercise behavior in twins aged approximately 7, 10, 12, 14, 16 and 18 years (N = 27,332 twins; 48 % males; 47 % with longitudinal assessments). Three exercise categories (low, middle, high) were analyzed by means of liability threshold models. First, a univariate model was fitted using the largest available cross-sectional dataset with linear and quadratic effects of age as modifiers on the means and variance components. Second, a simplex model was fitted on the longitudinal dataset. Heritability was low in 7-year-olds (14 % in males and 12 % in females), but gradually increased up to age 18 (79 % in males and 49 % in females), whereas the initially substantial relative influence of the shared environment decreased with age (from 80 to 4 % in males and from 80 to 19 % in females). This decrease was due to a large increase in the genetic variance. The longitudinal model showed the genetic effects in males to be largely stable and to accumulate from childhood to late adolescence, whereas in females, they were marked by both transmission and innovation at all ages. The shared environmental effects tended to be less stable in both males and females. In sum, the clear age-moderation of exercise behavior implies that family-based interventions might be useful to increase this behavior in children, whereas individual-based interventions might be better suited for adolescents. We showed that some determinants of individual differences in exercise behavior are stable across childhood and youth, whereas

  5. Academic and behavioral limitations and health-related quality of life in school-age survivors of bacterial meningitis.

    PubMed

    Koomen, Irene; Raat, Hein; Jennekens-Schinkel, Aag; Grobbee, Diederick E; Roord, John J; van Furth, Marceline

    2005-08-01

    The objectives of this study were to describe health-related quality of life of postmeningitic children and to examine the association between academic and/or behavioral limitations and health-related quality of life. One hundred and eighty-two children (mean age 9.7 years; range 5.3-14.2) were selected randomly from a cohort of 674 school-age children who recovered from non-Haemophilus influenzae type B bacterial meningitis. These children had neither meningitis with 'complex onset', nor prior cognitive or behavioral problems, nor severe disease sequelae. On average 7.4 years after meningitis, they were evaluated using an 'Academic Achievement Test' and their parents filled in the Child Behavior Checklist, the Child Health Questionnaire, and the Health Utilities Index. The long-term incidence of academic and/or behavioral limitations was 32%. Overall health-related quality of life of the postmeningitic children was decreased in comparison with that of a reference population of schoolchildren. The group of postmeningitic children with academic and/or behavioral limitations showed the most marked decrease in quality of life, especially concerning psychosocial health, cognition and family life. The negative effects on quality of life were not significantly influenced by age, gender, causative pathogen, presence of minor neurological impairment, or presence of hearing impairment. In conclusion, health-related quality of life of postmeningitic children is decreased, particularly of those with academic and/or behavioral limitations. PMID:16110936

  6. Bullying at Elementary School and Problem Behavior in Young Adulthood: A Study of Bullying, Violence, and Substance Use from Age 11 to Age 21

    PubMed Central

    Kim, Min Jung; Catalano, Richard F.; Haggerty, Kevin P.; Abbott, Robert D.

    2013-01-01

    Aim The main aim of this paper is to investigate to what extent self-reported bullying at grade 5 predicts later violence, heavy drinking and marijuana use at age 21. Method Univariate and multivariate associations between bullying and later outcomes were examined based on data from the Raising Health Children (RHC) project, a longitudinal study of the etiology of problem behavior and an experimental evaluation of a preventive intervention to reduce problem behavior. Results Childhood bullying was significantly associated with violence, heavy drinking and marijuana use at age 21. These associations held up after controlling for prior risk factors. Conclusions Childhood bullying had unique associations with risk of later violence and substance use among young adults. Early intervention to prevent childhood bullying may also reduce other adverse outcomes later in life. PMID:21370299

  7. Progression of multiple behavioral deficits with various ages of onset in a murine model of Hurler syndrome.

    PubMed

    Pan, Dao; Sciascia, Anthony; Vorhees, Charles V; Williams, Michael T

    2008-01-10

    Mucopolysaccharidosis type I (MPS I) is one of the most common lysosomal storage diseases with progressive neurological dysfunction. To characterize the chronological behavioral profiles and identify the onset of functional deficits in a MPS I mouse model (IDUA(-/-)), we evaluated anxiety, locomotor behavior, startle, spatial learning and memory with mice at 2, 4, 6 and 8 months of age. In automated open-field test, IDUA(-/-) mice showed hypoactivity as early as 2 months of age and altered anxiety starting from 6 months of age during the initial exploratory phase, even though normal habituation was observed at all ages. In the marble-burying task, the anxiety-like compulsive behavior was normal in IDUA(-/-) mice at almost all tested ages, but significantly reduced in 8-month old male IDUA(-/-) mice which coincided with the rapid death of IDUA(-/-) males starting from 7 months of age. In the Morris water maze, IDUA(-/-) mice exhibited impaired proficient learning only at 4 months of age during the acquisition phase. Spatial memory deficits were observed in IDUA(-/-) mice during both 1 and 7 days probe trials at 4 and 8 months of age. The IDUA(-/-) mice performed normally in a novel object recognition task at younger ages until 8 months old when reduced visual cognitive memory retention was noted in the IDUA(-/-) mice. In addition, 8-month-old IDUA(-/-) mice failed to habituate to repeated open-field exposure, suggesting deficits in non-aversive and non-associative memory. In acoustic startle assessment, significantly more non-responders were found in IDUA(-/-) mice, but normal performance was seen in those that did show a response. These results presented a temporal evaluation of phenotypic behavioral dysfunctions in IDUA(-/-) mice from adolescence to maturity, indicating the impairments, with different ages of onset, in locomotor and anxiety-like compulsive behaviors, spatial learning and memory, visual recognition and short-term non-associative memory retention

  8. Maternal age as a factor in determining the reproductive and behavioral outcome of rats prenatally exposed to ethanol.

    PubMed

    Vorhees, C V

    1988-01-01

    Nulliparous Long-Evans rats were bred at one of four different ages and assigned to one of three treatment groups within each age condition. Maternal ages were 9, 18, 32, and 36 weeks. Treatment groups were ethanol (E), administered by gavage as 8 g/kg in two divided doses on days 10-14 of gestation, pair-fed (PF) controls, administered as an isocaloric sucrose solution by gavage on days 10-14 of gestation, and ad lib fed controls (C). All offspring were surrogate fostered shortly after delivery to untreated recently parturient dams. Litter sizes were standardized to 8 on the day of birth. Offspring were assessed longitudinally for growth, mortality, and behavior (olfaction, locomotor activity, maze learning, avoidance acquisition and startle). Approximately 85% of the 36 week old dams did not produce viable litters. In the remaining maternal age conditions, ethanol delayed offspring olfactory orientation and increased locomotor activity, the latter dissipating after 50-60 days of age. These ethanol-related effects occurred independent of maternal age condition. Maternal age, independent of ethanol, was a factor which reduced litter size and offspring weight up to 50 days, but produced few effects on behavior. The combination of maternal age and prenatal ethanol interacted to increase pregnancy loss (oldest maternal age), reduce offspring weight up to day 99 (oldest and middle maternal age), alter olfactory orientation performance (oldest and middle maternal age), reverse the typical ethanol-induced increase in activity for males in the figure-8 test (oldest maternal age group), shift the pattern of open-field activity, and change errors in a complex water maze. Not all of these interactions turned out to be specific to the ethanol X old maternal age condition. Several of the interactions occurred in both the old and middle maternal age conditions. The only effect of old maternal age that interacted strongly with ethanol was in their combined effects on

  9. Measurement of irradiation effects in precipitate hardened aluminum using nonlinear ultrasonic principles (in-situ)

    NASA Astrophysics Data System (ADS)

    Reinhardt, B. T.; Parks, D. A.; Tittmann, B. R.

    2012-05-01

    Currently nuclear power plants are reaching the end of their initial design life. Yet, in order to meet the energy demands, twenty year extensions have been granted to many nuclear reactor facilities. These extensions will be ending by the year 2035, leaving a large gap in the available energy supply. In order to extend the life of these facilities it will imperative to develop techniques capable detecting damage in the aging nuclear facilities. However, the high temperature and high neutron flux environment limits the materials available for use in the nuclear reactor. Because of this limitation little NDE based inspection has been implemented in high radiation environments. Yet recent developments in the understanding of Aluminum Nitride (AlN) piezoelectric sensors high temperature and radiation dependent behavior have opened the door for in-situ experimentation. An experiment was designed to monitor the propagation of an ultrasonic wave in a precipitate hardened aluminum specimen while being subjected to radiation at the Pennsylvania State Universities Breazeale Reactor. Measurements of harmonic generation were made up to 1.85×1018 fluence with significant spectral difference between the pre-irradiated state and the post irradiated state. The connection between micro-structural material changes and harmonic measurements are addressed.

  10. Directionality between Tolerance of Deviance and Deviant Behavior Is Age-Moderated in Chronically Stressed Youth

    ERIC Educational Resources Information Center

    Ridenour, Ty A.; Caldwell, Linda L.; Coatsworth, J. Douglas; Gold, Melanie A.

    2011-01-01

    Problem behavior theory posits that tolerance of deviance is an antecedent to antisocial behavior and substance use. In contrast, cognitive dissonance theory implies that acceptability of a behavior may increase after experiencing the behavior. Using structural equation modeling, this investigation tested whether changes in tolerance of deviance…

  11. Does Age Matter Among Young Black Men Who Have Sex With Men? A Comparison of Risk Behaviors Stratified by Age Category.

    PubMed

    Chamberlain, Nicholas; Mena, Leandro; Geter, Angelica; Crosby, Richard A

    2016-06-01

    The purpose of this study is to assess whether different sexual risk behavior exists among young Black men who have sex with men (YBMSM) as a function of age. A total of 382 YBMSM completed a computer-assisted self-interview at a sexual health clinic. The frequency/prevalence of fifteen sexual risk behaviors was compared between three groups (ages 16-19, 20-25, and 26-29, respectively) in the 90 days prior to enrollment in the study. Regression models were used to control for the confounding influence of Human Immunodeficiency Virus (HIV) status. One hundred seven participants were HIV-infected at study enrollment. Of the 15 measures assessed, none significantly differed among the groups. These null findings did not change in multivariate analyses. Our findings suggest that there is no differential sexual risk based on age among YBMSM and that this group should be considered a homogenous population with regards to intervention strategies that aim to reduce the sexual risk behaviors of YBMSM. PMID:27244192

  12. Empirical beam hardening correction (EBHC) for CT

    SciTech Connect

    Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc

    2010-10-15

    Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern

  13. AMS-02 positron excess: New bounds on dark matter models and hint for primary electron spectrum hardening

    NASA Astrophysics Data System (ADS)

    Feng, Lei; Yang, Rui-Zhi; He, Hao-Ning; Dong, Tie-Kuang; Fan, Yi-Zhong; Chang, Jin

    2014-01-01

    The data collected by ATIC, CREAM and PAMELA all display remarkable cosmic ray nuclei spectrum hardening above the magnetic rigidity ∼240 GV. One natural speculation is that the primary electron spectrum also gets hardened (possibly at ∼80 GV) and the hardening partly accounts for the electron/positron total spectrum excess discovered by ATIC, HESS and Fermi-LAT. If it is the case, the increasing behavior of the subsequent positron-to-electron ratio will get flattened and the spectrum hardening should be taken into account in the joint fit of the electron/positron data otherwise the inferred parameters will be biased. Our joint fits of the latest AMS-02 positron fraction data together with the PAMELA/Fermi-LAT electron/positron spectrum data suggest that the primary electron spectrum hardening is needed in most though not all modelings. The bounds on dark matter models have also been investigated. In the presence of spectrum hardening of primary electrons, the amount of dark-matter-originated electron/positron pairs needed in the modeling is smaller. Even with such a modification, the annihilation channel χχ→μ+μ- has been tightly constrained by the Fermi-LAT Galactic diffuse emission data. The decay channel χ→μ+μ- is found to be viable.

  14. Supportive parenting mediates widening neighborhood socioeconomic disparities in children’s antisocial behavior from ages 5 to 12

    PubMed Central

    Odgers, Candice L.; Caspi, Avshalom; Russell, Michael A.; Sampson, Robert J.; Arsenault, Louise; Moffitt, Terrie E.

    2012-01-01

    In this article we report a graded relationship between neighborhood socioeconomic status (SES) and children’s antisocial behavior that (1) can be observed at school entry, (2) widens across childhood, (3) remains after controlling for family-level SES and risk, and (4) is completely mediated by maternal warmth and parental monitoring (defined throughout as supportive parenting). Children were participants in the Environmental Risk (E-Risk) Longitudinal Twin Study (n=2232), which prospectively tracked the development of children and their neighborhoods across childhood. Direct and independent effects of neighborhood-level SES on children’s antisocial behavior were observed as early as age 5 and the gap between children living in deprived versus more affluent neighborhoods widened as children approached adolescence. By age 12, the effect of neighborhood socioeconomic status on children’s antisocial behavior was as large as the effect observed for our most robust predictor of antisocial behavior – sex! (Cohen’s d = .51 when comparing children growing up in deprived versus more affluent neighborhoods in comparison to Cohen’s d = .53 when comparing antisocial behavior among boys versus girls). However, differences in children’s levels and rate of change in antisocial behavior across deprived versus more affluent neighborhoods were completely mediated by supportive parenting practices. Implications of our findings for studying and reducing socioeconomic disparities in antisocial behavior among children are discussed. PMID:22781850

  15. Lithium prevents parkinsonian behavioral and striatal phenotypes in an aged parkin mutant transgenic mouse model.

    PubMed

    Lieu, Christopher A; Dewey, Colleen M; Chinta, Shankar J; Rane, Anand; Rajagopalan, Subramanian; Batir, Sean; Kim, Yong-Hwan; Andersen, Julie K

    2014-12-01

    Lithium has long been used as a treatment for the psychiatric disease bipolar disorder. However, previous studies suggest that lithium provides neuroprotective effects in neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease. The exact mechanism by which lithium exerts these effects still remains unclear. In the present study, we evaluated the effects of low-dose lithium treatment in an aged mouse model expressing a parkin mutation within dopaminergic neurons. We found that low-dose lithium treatment prevented motor impairment as demonstrated by the open field test, pole test, and rearing behavior. Furthermore, lithium prevented dopaminergic striatal degeneration in parkin animals. We also found that parkin-induced striatal astrogliosis and microglial activation were prevented by lithium treatment. Our results further corroborate the use of this parkin mutant transgenic mouse line as a model for PD for testing novel therapeutics. The findings of the present study also provide further validation that lithium could be re-purposed as a therapy for PD and suggest that anti-inflammatory effects may contribute to its neuroprotective mechanisms. PMID:25452026

  16. Psychopathic personality traits in middle-aged male twins: a behavior genetic investigation.

    PubMed

    Brook, Michael; Panizzon, Matthew S; Kosson, David S; Sullivan, Elizabeth A; Lyons, Michael J; Franz, Carol E; Eisen, Seth A; Kremen, William S

    2010-08-01

    Psychopathic personality is characterized by interpersonal dominance, impulsivity, sensation seeking, poor planning, and aggressiveness. Studies have shown that the Multidimensional Personality Questionnaire (MPQ) can be used to estimate scores on the fearless-dominant (FD) and the impulsive-antisocial (IA) dimensions of the Psychopathic Personality Inventory (PPI), the best validated self-report measure of psychopathic personality traits. Prior behavior genetic studies reported roughly equal genetic and nonshared environmental influences for both FD and IA, which remained stable from adolescence to young adulthood. However, no prior studies address genetic and environmental influences on these dimensions beyond early adulthood. We utilized the classic twin method to examine genetic and environmental influences on variance in FD and IA in a sample of middle-aged male twins. Biometric modeling indicated that the variance in both factors is best explained by additive genetic and nonshared environmental influences. FD showed roughly equal contributions from genetic and environmental factors, whereas IA showed greater contributions from environmental than genetic factors. Additionally, the small phenotypic correlation between FD and IA was explained entirely by nonshared environmental factors. PMID:20695807

  17. Quantifying Age-Related Differences in Information Processing Behaviors When Viewing Prescription Drug Labels

    PubMed Central

    Sundar, Raghav Prashant; Becker, Mark W.; Bello, Nora M.; Bix, Laura

    2012-01-01

    Adverse drug events (ADEs) are a significant problem in health care. While effective warnings have the potential to reduce the prevalence of ADEs, little is known about how patients access and use prescription labeling. We investigated the effectiveness of prescription warning labels (PWLs, small, colorful stickers applied at the pharmacy) in conveying warning information to two groups of patients (young adults and those 50+). We evaluated the early stages of information processing by tracking eye movements while participants interacted with prescription vials that had PWLs affixed to them. We later tested participants’ recognition memory for the PWLs. During viewing, participants often failed to attend to the PWLs; this effect was more pronounced for older than younger participants. Older participants also performed worse on the subsequent memory test. However, when memory performance was conditionalized on whether or not the participant had fixated the PWL, these age-related differences in memory were no longer significant, suggesting that the difference in memory performance between groups was attributable to differences in attention rather than differences in memory encoding or recall. This is important because older adults are recognized to be at greater risk for ADEs. These data provide a compelling case that understanding consumers’ attentive behavior is crucial to developing an effective labeling standard for prescription drugs. PMID:22719955

  18. Deep Drawing Simulation Of High And Ultrahigh Strength Steels Under Consideration Of Anisotropic Hardening

    SciTech Connect

    Roll, Karl; Faust, Alexander; Kessler, Lutz

    2007-05-17

    In today's sheet metal forming simulation, most attention is paid to yield loci functions, which describe the anisotropy of the material in yielding. The coefficients, defining the shape of the yield locus in these functions are usually fitted at a certain level of plastic work and are then valid for the whole range of plastic deformation. Modern high and ultrahigh strength steels, especially those with induced plasticity, may often exhibit only a very small anisotropy in yielding, but a severe anisotropy in work hardening for different loading conditions. This behavior can not be described by fitting the yield locus at a specific value of plastic deformation. An approach to take into account the anisotropic hardening of sheet metals is to provide different yield curves for several loading conditions and expand the yield locus dependent on the current form of load. By doing this, one can use a comparatively simple yield locus, like that of Hill from 1948, because all anisotropy is given by the different hardening curves. For the commercial FEM code LS DYNA the material model MATFEM Generalized Yield is available as a user subroutine, which supports this approach. In this paper, forming simulation results of different yield loci are compared with experimental results. The simulations were carried out in LS-DYNA with the Barlat 89 and 2000 yield loci and isotropic hardening and with the GenYld model combining a Hill 48 yield locus and anisotropic hardening. The deep drawing experiments were conducted on a hydraulic press, measuring binder and punch forces. The deformation of the sheet was measured by optical grid analysis. A comparison of the simulated and measured plastic strains shows that using a model including anisotropic hardening can produce better results than the usage of a complex yield locus but isotropic hardening for the examined materials. This might be interesting for e.g. spring back simulations. By combining a simple yield locus with anisotropic

  19. Aging Exacerbates Depressive-like Behavior in Mice in Response to Activation of the Peripheral Innate Immune System

    PubMed Central

    Godbout, Jonathan P; Moreau, Maïté; Lestage, Jacques; Chen, Jing; Sparkman, Nathan L; O’Connor, Jason; Castanon, Nathalie; Kelley, Keith W; Dantzer, Robert; Johnson, Rodney W

    2010-01-01

    Exposure to peripheral infections may be permissive to cognitive and behavioral complications in the elderly. We have reported that peripheral stimulation of the innate immune system with lipopolysaccharide (LPS) causes an exaggerated neuroinflammatory response and prolonged sickness behavior in aged BALB/c mice. Because LPS also causes depressive behavior, the purpose of this study was to determine whether aging is associated with an exacerbated depressive-like response. We confirmed that LPS (0.33 mg/kg intraperitoneal) induced a protracted sickness response in aged mice with reductions in locomotor and feeding activities 24 and 48 h postinjection, when young adults had fully recovered. When submitted to the forced swim test 24 h post-LPS, both young adult and aged mice exhibited an increased duration of immobility. However, when submitted to either the forced swim test or the tail suspension test 72 h post-LPS, an increased duration of immobility was evident only in aged mice. This prolonged depressive-like behavior in aged LPS-treated mice was associated with a more pronounced induction of peripheral and brain indoleamine 2,3-dioxygenase and a markedly higher turnover rate of brain serotonin (as measured by the ratio of 5-hydroxy-indoleacetic acid over 5-hydroxyt-tryptamine) compared to young adult mice at 24 post-LPS injection. These results provide the first evidence that age-associated reactivity of the brain cytokine system could play a pathophysiological role in the increased prevalence of depression observed in the elderly. PMID:18075491

  20. Aging induced loss of complexity and dedifferentiation: consequences for coordination dynamics within and between brain, muscular and behavioral levels

    PubMed Central

    Sleimen-Malkoun, Rita; Temprado, Jean-Jacques; Hong, S. Lee

    2014-01-01

    Growing evidence demonstrates that aging not only leads to structural and functional alterations of individual components of the neuro-musculo-skeletal system (NMSS) but also results in a systemic re-organization of interactions within and between the different levels and functional domains. Understanding the principles that drive the dynamics of these re-organizations is an important challenge for aging research. The present Hypothesis and Theory paper is a contribution in this direction. We propose that age-related declines in brain and behavior that have been characterized in the literature as dedifferentiation and the loss of complexity (LOC) are: (i) synonymous; and (ii) integrated. We argue that a causal link between the aforementioned phenomena exists, evident in the dynamic changes occurring in the aging NMSS. Through models and methods provided by a dynamical systems approach to coordination processes in complex living systems, we: (i) formalize operational hypotheses about the general principles of changes in cross-level and cross-domain interactions during aging; and (ii) develop a theory of the aging NMSS based on the combination of the frameworks of coordination dynamics (CD), dedifferentiation, and LOC. Finally, we provide operational predictions in the study of aging at neural, muscular, and behavioral levels, which lead to testable hypotheses and an experimental agenda to explore the link between CD, LOC and dedifferentiation within and between these different levels. PMID:25018731