Synthesis of amorphous and quasicrystal phases by mechanical alloying of Ti 45 Zr 38 Ni 17 powder mixtures,and their hydrogenation

Mechanical alloying of Ti 45 Zr 38 Ni 17 powder mixture forms an amorphous phase, but subsequent annealing causes the formation of an icosahedral ( i ) phase. The maximum hydrogen concentration that can be loaded at 573K at a hydrogen pressure of 3.8MPa is the same (\[H]/\[M] 1.5) for the amorphous and i -phase powders. With hydrogenation, the i -phase is almost stable, forming no hydrides, whereas the amorphous phase transforms to a fcc hydride. The activation energy for hydrogen desorption for the i -phase is about 127kJmol -1, which is lower than that for the amorphous phase, suggesting that the i -phase powder may have better properties for hydrogen-storage applications.     

Effect of local chemistry,structure and length scale of heterogeneities on the mechanical properties of a Ti45Cu40Ni7.5Zr5Sn2.5 bulk metallic glass

We report on distinct variations in local chemistry, structure and length scale of heterogeneous regions in Ti₄₅Cu₄₀Ni_7.5Zr₅Sn_2.5 fully glass rods of different diameters, i.e. rods subjected to different cooling rates. The present investigations indicate that the mechanical properties of the Ti₄₅Cu₄₀Ni_7.5Zr₅Sn_2.5 bulk metallic glass can be modified within a wide range of strength and plastic deformability by controlling the scale of the heterogeneous regions in the glass through appropriate variation of the cooling rate applied for solidification.     

Effects of crystallization on corrosion resistance and electron work function of Zr65Al7.5Cu17.5Ni10 amorphous alloys

The effects of crystallization on the electron work function and corrosion resistance of Zr₆₅Al_7.5Cu_17.5Ni₁₀ amorphous alloys have been studied. The single-phase amorphous alloy exhibits a better corrosion resistance and has a higher work function than the partially and fully crystallized alloys with the same composition. The close relationship between corrosion resistance and work function indicates that the Kelvin probe technique can be a powerful tool for characterizing the corrosion behaviour of amorphous alloy on an electronic level.     

Effects of nutritional and mechanical properties of food on ruminative behavior.

Previous studies have identified a reliable relation between the quantity of food ingested and ruminating in profoundly retarded individuals and have established some parametric characteristics of this relation. The present study investigated three different properties of food that may influence this relation. Experiment 1 examined the role of stomach distention produced by including in the subject's diet wheat bran in amounts equivalent to and exceeding the calculated amount of crude fiber in the starch-satiation diet reported by Rast, Johnston, Drum, and Conrin (1981) and Rast, Johnston, and Drum (1984). There was a decrease in ruminating, although this decrease was smaller and more gradual than in the starch-satiation condition. Experiment 2 showed that increasing calories without increasing food volume resulted in a gradual and moderate decrease in ruminating. Experiment 3 replicated and extended the first two experiments by varying both caloric intake and stomach distention as well as oropharyngeal and esophageal stimulation in a different sequence of conditions. All variables exerted some control over responding. However, the large and immediate effects of the starch-satiation procedure occurred only when subjects were permitted to consume unlimited quantities.     

Changes of hardness and electronic work function of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass on annealing

The hardness and electronic work function (EWF) of a bulk metallic glass, namely Zr_41.2Ti_13.8Cu_12.5Ni₁₀Be_22.5, have been studied experimentally, with an emphasis on the effect of heat treatments. The glass was annealed at different time and temperatures, and its hardness and EWF measured using the Rockwell indentation technique and a scanning Kelvin probe system, respectively. It is found that the EWF decreases with annealing time and temperature, whereas the hardness increases. This study shows a close relationship between hardness and EWF, indicating that the EWF could be a sensitive parameter for characterising and investigating the mechanical behaviour of BMG at the electronic level.     

Structural effects on diffusion in metallic glasses: The pressure dependence of Ni diffusion in as-quenched and relaxed Co42Zr58

In order to clarify the role of thermal defects in diffusion in metallic glasses, we have measured the temperature and pressure dependences of diffusion of Ni, a probe for Co, in relaxed and non-relaxed amorphous Co₄₂Zr₅₈ alloys by means of the tracer technique in combination with secondary-ion mass spectroscopy. For the relaxed state, the activation energy and the pre-factor are Q _{= (}1:65=0:08₎ eV and D _{0 =} 2:4+3:9 10-6m2 s-1 respectively. The pressure - 1:9 dependence yields an activation volume V _{act = (}0:66 0:15₎Omega, with Omega being the average atomic volume of the alloy. This value is similar to activation volumes in crystalline materials and is indicative of diffusion via thermally generated defects. Unlike monovacancies in crystals, these defects appear to be spread out, judging from recent isotope-effect measurements. Comparison with literature data shows that the activation volume and hence the diffusion mechanism in metallic glasses clearly depend on the structure and composition even for the very same component. The activation volume in the as-quenched state was found to be _{( )} ^{0:93 0:25 Omega.}     

Writing about patients: II. Patients' reading about themselves and their analysts' perceptions of its effect

Thirty American analysts who have published articles that include clinical material were interviewed about their methods for ensuring patient confidentiality. Eight of these analysts had patients who had read about themselves or heard their cases presented, though their analyst had not requested permission to use this material. Eighteen patients had been asked and gave their consent to have their material used. Twelve of these patients were shown the material written about them. The analysts' thoughts and reactions to their experiences of obtaining consent and having their patients read material about themselves, and of disguising material without asking consent and then having it inadvertently discovered and read by their patients, are discussed. Their views of the effect on their patients of reading written material about themselves are elaborated with case illustrations.     

The properties of retention intervals and their affect on retaining prospective memories

Five experiments were conducted to explore how the character of the retention interval affected event-based prospective memory. According to the canons of retrospective memory, prospective performance should have been worse with increasing delays between intention formation and the time it was appropriate to complete an action. That result did not occur. Rather, prospective memory was better with increasing retention intervals in Experiments 1A, 1B, and 3. In manipulating the nature of the retention interval, the authors found that there were independent contributions of retention interval length and the number of intervening activities, with more activities leading to better prospective memory (Experiments 2 and 3). The identical retention intervals did not improve retrospective memory in Experiment 4. Theoretical explanations for these dissociations between prospective and retrospective memory are considered.     

Effect of heat treatment on the microstructure and mechanical properties of spray-formed 7055 aluminium alloy

7055 Al alloys samples were prepared by spray forming and hot-extrusion followed by two different aging treatment procedures. Their different distributions of GP zones, and nanoscale precipitates η′ (MgZn) and η (MgZn₂) are extensively investigated by transmission electron microscope (TEM). The mechanical properties, including tensile strength, Vickers hardness and elongation of both aged 7055 Al alloys, have also been measured and analysed. It is found that T6 and T76 aging treatment results in quite different microstructure and mechanical properties. The outstanding performance of the 7055 Al alloys after T6 aging treatment is attributed to nanoscale semi-coherent dispersion precipitates.     

The properties of geophysical fields and their effects on elephants and other animals

Geophysical properties of acoustic, seismic, electric, and magnetic waveforms create opportunities and constraints for animals' communication and sensory monitoring of the environment. The geometric spreading of waves differs; at some frequencies, transmission is most efficient and has minimal noise. The spreading properties of seismic waves favor long-distance propagation for communication and environmental monitoring, and would benefit elephants (Elephas maximus and Loxodonta africana), such as in locating subsurface water. Extending C. E. O'Connell-Rodwell, B. T. Amason, and L. A. Hart (2000), a man jumping at 1.11 km propagated seismic waves at 10-40 Hz. Given the noise of lightning and the Schumann resonances, near field magnetic and electric transmission by animals would be most efficient around 1000 Hz.     

味觉对判断与决策的影响及其机制

味觉作为人类生存必不可少的感觉之一, 早已超越“舌尖”的直接感受, 潜在地影响了个体对人际关系及伦理道德的知觉与判断, 改变着个体对冒险与消费等行为的决策。情绪中介假说、具身隐喻假说、进化假说以及社会建构假说从不同视角试图阐明味觉对判断与决策的影响机制。当前研究存在味觉感受存在个体差异、味觉测量难以保证效度、味觉实验缺乏统一研究范式等问题, 未来可继续进行味觉隐喻的验证并将其应用于感官营销、心理治疗等领域, 从生理、心理及社会等多个层面出发, 全方位探讨味觉对判断、决策的影响及其机制。     

藏语阅读中中央凹词频效应及对副中央凹预视效应的影响

在不同语言文字系统中,对于眼动控制的本质及其发生机制,尤其是阅读过程中注意资源的分配是序列分布还是平行分布的问题,目前仍然存在着争论和分歧。藏语是拼音文字,但它同时又具有汉语的特点,独具语言特色。因此,通过对藏语阅读过程中中央凹词频对副中央凹预视效应影响这一问题的探讨,可以在一种已有研究未曾涉及的文字系统中进一步推动上述争议的解决。本研究采用眼动记录法,设计了两个实验。实验1操纵了中央凹词频(高频、低频),考察藏语阅读中中央凹词的词频效应及词频延迟效应,结果发现,藏语阅读中存在词频效应及词频延迟效应。实验2同时操纵中央凹词频和副中央凹预视词类型,借助边界范式,考察藏语阅读中副中央凹预视效应及中央凹词频对副中央凹预视效应的影响,结果发现,藏语阅读中存在副中央凹预视效应,且与低频中央凹词相比,高频中央凹词对副中央凹预视效应的促进作用更大。两个实验结果表明:(1)藏语阅读中存在显著的词频效应,且表现在词汇加工的整个过程;(2)藏语阅读中存在显著的词频延迟效应,并贯穿于词汇加工的整个过程;(3)藏语阅读中存在显著的副中央凹预视效应,读者能通过副中央凹预视提取到语音和字形信息。藏语阅读中中央凹词...     

Stimulus properties of facial expressions and their influence on the classical conditioning of fear

The influence of particular stimulus properties of facial expressions of emotion upon associative learning to a neutral cue was examined in the present investigation. A compound stimulus, composed of either a fearful, happy, or neutral facial expression paired with a neutral cue (tone), signaled an aversive event (mild electric shock). Phasic change in skin conductance (SC) was used as the measure of associative learning. Analyses of variance revealed that subjects who saw a fearful expression paired with the tone gave larger SC responses to the fearful expression than to the tone. The opposite pattern was obtained for subjects who had a happy expression paired with the tone. Subjects who had the neutral expression paired with the tone showed no significant difference in their responses to the two stimuli. Results of the present investigation were consistent with those of an earlier study by Lanzetta and Orr (1980), and extend the earlier theoretical interpretations by suggesting that fear expressions function as excitatory stimuli and happy expressions act as inhibitory stimuli. Methodological changes in the present study, which include a shorter CS interval and asynchronous stimulus onsets, also extend the previous findings.This research was supported by National Science Foundation Grant No. 7912422-AO1 and by funds from the Lincoln Filene endowment to Dartmouth College.     

The effect of divided attention on memory for items and their context.

Memory for context, in comparison to memory for items, is a more demanding task and requires more attentional resources. We examined differences between item and context memory using divided attention at encoding and retrieval. Participants were presented with word lists and were instructed to learn the items (i.e., words), the intrinsic context (i.e., the colour of the cards on which each word was presented), and the extrinsic context (i.e., the temporal order of the words). Among 72 young adults, in comparison to conditions of full attention, divided attention applied at encoding only or retrieval only resulted in equally lower performance on all memory tasks; in contrast, divided attention applied at both encoding and retrieval resulted in lower performance only on memory for temporal order. The findings support the idea that memory for temporal order requires greater attentional resources and strategic processing than memory for items.