Thermal effects on pressure-induced infiltration of a nanoporous system

Thermal effects on the energy absorption efficiency of a system consisting of hydrophobic mesoporous silica particles immersed in water have been investigated. As the temperature increases, although the infiltration pressure decreases only slightly and the accessible pore volume remains nearly constant, the system recoverability can be significantly improved, primarily due to an increase in outflow pressure. The sequence of changing pressure and temperature has little influence on the system performance.     

Electromechanical behavior of single-walled carbon nanotube thin films

Carbon nanotubes have been intensively studied owing to their great potential in nanoelectronics and nanomechanical devices. Recently, experimental results have shown that single-walled carbon nanotubes (SWCNTs) change their electronic properties when subjected to strain. In this study, the electromechanical characteristics of SWCNT networks were investigated for the application of printable strain sensors on flexible substrates. SWCNT films were formed on plastic substrates of poly(ethylene terephthalate) using a spray process. In this manner, we were able to control the transparency and obtain uniform electrical properties of the films. The films are isotropic on account of the random orientation of bundles of SWCNTs. Experimental results showed a nearly linear change in the resistance across a film when it was subjected to tensile strain, even in the inelastic range of the flexible substrate. The results demonstrate the potential use of SWCNT films for highly sensitive printable strain sensors on a macroscale.     

Thermal effects on infiltration of a solubility-sensitive volume-memory liquid

As the ion density at a solid–liquid interface changes, the interfacial tension varies accordingly, which can lead to a large energy density output, particularly when amplified by the high specific surface area of a nanoporous material. This concept is validated by the results of a controlled-temperature infiltration experiment on a hydrophobic zeolite immersed in a saturated aqueous solution of sodium acetate. As the temperature changes, the sodium acetate concentration varies significantly, which in turn causes a variation in infiltration pressure. Since the infiltration and defiltration are reversible, under the working pressure, this system exhibits a volume memory characteristic, with a non-monotonic temperature–volume relationship.     

Microstructural evolution of single-walled carbon nanotubes under electron irradiation

A sample containing single-wall carbon nanotubes (SWCNTs) has been annealed at 900°C and then irradiated by high-energy electrons in an ultrahigh-vacuum transmission electron microscope. Sequential high-resolution images showed that the structures of SWCNT bundles and individual SWCNT segments first collapsed into disordered and fullerene-like carbon materials and then reorganized into graphitic particles under continuous electron irradiation. The speed of structural evolution is dependent on the flux density of the electron irradiation.     

Importance of chamber gas pressure on processing of Al-based metallic glasses during melt spinning

The effect of chamber gas pressure on the amorphicity of Al₈₅Ni₅Y₁₀ alloy was studied for the melt-spinning process. The amorphicity of as-quenched ribbons was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The chamber atmosphere pressure is crucial to the cooling rate of melt spinning. At high vacuum, at pressure less than 0.001?atm, fully crystalline fragments are obtained. Monolithic amorphous ribbons were only obtained at a gas pressure of 0.1?atm, 0.2?atm or higher. The extended contact length between ribbons and the copper wheel contributes to the high cooling rate of melt spinning in Al-based glass forming alloys; that is supported by images recorded by a high-speed camera. Higher chamber pressure increases contact length between ribbons and the wheel, which is qualitatively elucidated by Bernoulli's equation.     

社会价值取向与损失情境对不同时间压力下双人社会困境中合作行为的影响

为揭示双人社会困境中合作行为的影响因素,选取四种不同类型的双人社会困境,采用实验法考察社会价值取向与损失情境对不同时间压力下合作行为的影响。结果显示,亲社会个体的合作率显著高于亲自我个体的合作率,收益情境下的合作率显著高于损失情境下的合作率,在社会困境中双方冲突程度越大合作率越低;此外,高时间压力提升了亲自我个体在囚徒困境以及收益情境下信任困境中的合作率,同时降低了亲自我个体在损失情境下最大差异困境中的合作率。结果表明,社会价值取向、收益损失情境以及困境冲突程度均对合作行为的发生具有影响作用,而时间压力对合作行为的作用也同样受到三者的影响。这些发现能够为合作行为自动性的理论分歧提供新的证据。     

Peer pressure and risk taking in young drivers’ speeding behavior

Although many countermeasures have been implemented in Europe, young drivers continue to have a high rate of involvement in car crashes. Their crash rate is higher in presence of peer passengers than when driving alone. Peer presence could contribute toward explaining this involvement, especially regarding speeding. Peers are known to often influence young drivers’ risky behaviors through proximal (direct and indirect active pressures) and distal (passive pressure) forms of intervention (Allen & Brown, 2008). This present study examined the effect of peer pressure and peer risk taking on the estimated speeding behavior of a scenario driver (ESBSD) as well as on the estimated speeding intention of a scenario driver (ESISD). The scenario driver was the main character in an online-scenario based questionnaire regarding speeding. The main character is a fictional young male depicted driving with his best friends in all the experimental scenarios in which the variables type of pressure and peer risk taking were manipulated. One hundred and eighty young French drivers (18–25 years, 50% men) took part in the study. The key findings were that (1) only direct and indirect active pressure, but not passive pressure, increased the ESBSD and that (2) high (vs. low) peer risk taking lead to a higher ESISD. However, no interaction between the pressure type and peer risk taking on ESBSD and ESISD was found. Implications of the findings are discussed.     

The paraventricular nucleus of the hypothalamus is involved in cardiovascular responses to acute restraint stress in rats

The paraventricular nucleus of the hypothalamus (PVN) has been implicated in several aspects of cardiovascular control. Stimulation of the PVN evokes changes in blood pressure and heart rate. Additionally, this brain area is connected to several limbic structures implicated in behavioral control, as well as to forebrain and brainstem structures involved in cardiovascular control. This evidence indicates that the PVN may modulate cardiovascular correlates of behavioral responses to stressful stimuli. Acute restraint is an unavoidable stressor that evokes marked and sustained cardiovascular changes, which are characterized by elevated mean arterial pressure (MAP) and an intense heart rate (HR) increase. We report on the effect of inhibition of PVN synapses on MAP and HR responses evoked by acute restraint in rats. Bilateral microinjection of the nonspecific synaptic blocker cobalt (CoCl(2), 1 mM/100 nl) into the PVN did not change the HR response or the initial peak of the MAP response to restraint stress, but reduced the area under the curve of the MAP response. Moreover, bilateral microinjection of cobalt in areas surrounding the PVN did not change the cardiovascular response to restraint. These results indicate that synapses in the PVN are involved in the neural pathway that controls blood pressure changes evoked by restraint.     

Tonic and phasic stimulus control of blood pressure responses using opposing unconditional stimuli

The transswitching paradigm was used in the present study to investigate the effects of tonic (long duration) environmental stimuli paired with opposing unconditional stimuli on human blood pressure. Sixty volunteers participated for two sessions, one week apart. Subjects were presented with a pseudorandom sequence of four trials of red lights (five minutes each) and four trials of blue lights (five minutes each) within each session. All subjects received the cold pressor test during the red lights. During the blue lights, half the subjects received warm water and the other half received a neutral temperature water. Subjects received the presentations of the water in one of three methods: as determined by the experimenter, preceded by a warning signal, or self-administered. The results indicated that conditional and unconditional responses during the red lights were progressive increases in blood pressure. During the blue lights associated with warm water, conditional and unconditional responses were often progressive decreases in blood pressure. The method of administration of the water affected the magnitude of the unconditional responses. Evidence for phasic stimulus control was not as unequivocal as tonic stimulus control. The present results indicated that it is possible to modify blood pressure in two directions (increases and decreases) when two high contrast, opposing unconditional stimuli are presented.     

A mechanical method for changing heart rate and blood pressure

The investigation of afferent cardiovascular influences upon central nervous processes needs a methodology which allows for independent and systematic manipulation of circulatory processes. By mechanical manipulation of posture (tilt table, orthostasis) and compression of lower body parts (by anti-G-suit) reliable changes in heart rate and blood pressure can be induced. In fourty subjects (study 1) it could be shown that sustained (30 min.) changes in heart rate (e.g. orthostatic tachycardia, decrease of heart rate during compression) and mean arterial blood pressure (increase during orthostasis with and without compression) occur. Although changes in heart rate could be achieved irregardless of whether the venous "pooling" was suppressed by an air- or water-filled pressure suit, the pressor effect did differ quite considerably. In fourty-four subjects (study 2) it could be demonstrated that only by means of an water-filled suit further increases in mean arterial blood pressure could be evoked during orthostasis. Changes in hemodynamic also lead to changes in sympatho-vagal control of cardiac activity. In study 3 (ten subjects) it could be shown, that orthostasis mainly evokes alterations in sympathetic activity whereas lower body compression leads to additional increases of vagal activity and respiratory sinus arrhythmia during orthostasis.     

Anisotropic thermal properties of single-wall-carbon- nanotube-reinforced nanoceramics

Dense single-wall-carbon-nanotube-(SWCNT)-reinforced alumina nanocomposites have been fabricated by a novel spark-plasma-sintering technique. Anisotropic thermal properties have been found in carbon nanotube composites. The introduction of ropes of SWCNTs gives rise to a decrease in the transverse thermal diffusivity with increasing carbon nanotube content while it does not change the in-plane thermal diffusivity. This is scientifically interesting and technologically important for the development of materials for novel thermal barrier coatings.     

Classical conditioning of blood pressure inMacaca mulatta with cardiac rate controlled

The interaction of heart rate and blood pressure responses was studied in four male rhesus monkeys (M. mulatta) during classical delay conditioning and extinction. During initial conditioning sessions, heart rate was held constant by means of an external cardiac pacemaker; in follow-up conditioning sessions, the heart was free of constraint. Observations were made after these conditioning sessions, (a) during several sessions given over to continued training while different pacing rates were in effect; (b) during a series of extinction sessions in which the heart was paced and unpaced; and, (c) when a heart rate CR was simulated by manipulation of the pacer with no conditioned or unconditioned stimuli present. Throughout all sessions, systolic and diastolic pressures were measured at each heart beat. It was found that blood pressure conditioning was largely unaffected when heart rate changes were prevented during acquisition. Extinction of blood pressure responses was also seen to proceed relatively unimpeded when the heart was paced at a fixed frequency. During the postacquisition conditioning sessions, the several different pacing rates that were tested did not produce any significant differential effects in the blood pressure CRs. Simulated heart rate CRs were accompanied by small changes in pressures, sometimes opposite in direction from the pressure CRs observed during unpaced conditioning trials.     

Anticipatory balance control is affected by loadless training experiences

The main purpose of this study was to identify whether a lot of sports training had any effect on the balance control associated with a leg movement. The nature of the training experience was also an important concern and we chose subject who had undergone specific training experience in absence of equilibrium constraints. To this end a comparison between control (untrained) subjects, triathletes and swimmers was designed to establish whether a general training in sports (triathletes) or a specific loadless training (swimmers), leads to differences in the balance control. A leg movement is preceded by a shift of the center of mass (CM) towards the supporting side to maintain equilibrium and forward to create the condition for progression. To provide an acceleration of the CM sideward and forward, an initial displacement of the center of pressure (CP) towards the moving limb and in posterior direction was performed. Interestingly, the lateral pressure onto the ground was greater increased in swimmers in both leg raising and obstacle avoidance tasks compared to the control group and/or triathletes whereas the backward CP shift in all group was the same. The initial control of the CM shift is very different in swimmers compared to triathletes and controls. The increased lateral pressure onto the ground in swimmers may be a result of a prolonged training in water. This suggests that prolonged training in the absence of equilibrium constraints has more of an effect on balance control than a prolonged general training. In addition, the lack of differences in the backward CP shift suggests that M/L and A/P controls support two functional goals: equilibrium maintenance and movement initiation.     

Self-experimentation as a source of new ideas: ten examples about sleep, mood, health, and weight

Little is known about how to generate plausible new scientific ideas. So it is noteworthy that 12 years of self-experimentation led to the discovery of several surprising cause-effect relationships and suggested a new theory of weight control, an unusually high rate of new ideas. The cause-effect relationships were: (1) Seeing faces in the morning on television decreased mood in the evening (> 10 hrs later) and improved mood the next day (> 24 hrs later), yet had no detectable effect before that (0-10 hrs later). The effect was strongest if the faces were life-sized and at a conversational distance. Travel across time zones reduced the effect for a few weeks. (2) Standing 8 hours per day reduced early awakening and made sleep more restorative, even though more standing was associated with less sleep. (3) Morning light (1 hr/day) reduced early awakening and made sleep more restorative. (4) Breakfast increased early awakening. (5) Standing and morning light together eliminated colds (upper respiratory tract infections) for more than 5 years. (6) Drinking lots of water, eating low-glycemic-index foods, and eating sushi each caused a modest weight loss. (7) Drinking unflavored fructose water caused a large weight loss that has lasted more than 1 year. While losing weight, hunger was much less than usual. Unflavored sucrose water had a similar effect. The new theory of weight control, which helped discover this effect, assumes that flavors associated with calories raise the body-fat set point: The stronger the association, the greater the increase. Between meals the set point declines. Self-experimentation lasting months or years seems to be a good way to generate plausible new ideas.     

时间压力和相似性对类比推理直觉加工的影响

通过两个实验探讨了时间压力对类比推理的直觉加工的影响。实验1采用三因素混合实验设计,以48名大学生为被试,在不同时间压力条件下对不同相似性言语类比推理题进行喜好度判断和类比推理逻辑判断。实验2是在实验1的基础上用图形类比推理题代替语义类比推理题,以56名大学生为被试。结果发现:(1)时间压力下,对跨领域言语类比推理的直觉加工效应显著高于逻辑加工效应;(2)时间压力下,低难度图形类比推理题的直觉加工效应显著高于逻辑加工效应。无时间压力条件下,图形类比推理的逻辑加工效应优势明显;(3)时间压力对类比推理的直觉加工和逻辑加工均有影响     

Psychosocial mediators of racial differences in nighttime blood pressure dipping among normotensive adults.

Shallow declines in nocturnal compared with diurnal blood pressure (BP dipping) have been associated with cardiovascular disease. In U.S. samples, Blacks demonstrate less BP dipping compared with Whites. In a sample of 60 Black and 60 White normotensive adults we examined stress, social integration (including parental status), social support, and hostility as potential mediators of the association between race and BP dipping. The effect of race on diastolic BP dipping was partially mediated by parental status. The effect of race on heart rate dipping was partially mediated by stressful life events. No psychosocial factors mediated the relation between race and systolic BP dipping. Although psychosocial factors appear to account for some of the observed racial differences in nocturnal blood pressure decline, our data suggest that these differences cannot be attributed entirely to covarying psychosocial effects.     

Implementation intentions and disengagement from a failing course of action

We explored the consequences of forming implementation intentions that call for action (adjustment of chosen course of action) versus reflection (assessment of the appropriateness of chosen course of action) in situations that activate people's tendency to remain committed to failing courses of action. In Study 1, when negative experiences preceded failure, action and reflection implementation intention participants showed higher rates of disengagement than mere goal intention and no intention participants. However, when positive experiences preceded failure, only action implementation intention participants maintained this high disengagement rate. In Study 2, we observed that time pressure moderated the facilitating effects of action and reflection implementation intentions on disengagement when negative experiences preceded failure. Whereas the effect of action implementation intentions benefited from time pressure, the effect of reflection implementation intentions did not. The present studies construe disengagement as a self-regulation process and highlight the benefits of implementation intentions as a self-regulation tool. Copyright © 2006 John Wiley & Sons, Ltd.     

Spectral indices of cardiovascular adaptations to short-term simulated microgravity exposure

We investigated the effects of exposure to microgravity on the baseline autonomic balance in cardiovascular regulation using spectral analysis of cardiovascular variables measured during supine rest. Heart rate, arterial pressure, radial flow, thoracic fluid impedance and central venous pressure were recorded from nine volunteers before and after simulated microgravity, produced by 20 hours of 6° head down bedrest plus furosemide. Spectral powers increased after simulated microgravity in the low frequency region (centered at about 0.03 Hz) in arterial pressure, heart rate and radial flow, and decreased in the respiratory frequency region (centered at about 0.25 Hz) in heart rate. Reduced heart rate power in the respiratory frequency region indicates reduced parasympathetic influence on the heart. A concurrent increase in the low frequency power in arterial pressure, heart rate, and radial flow indicates increased sympathetic influence. These results suggest that the baseline autonomic balance in cardiovascular regulation is shifted towards increased sympathetic and decreased parasympathetic influence after exposure to short-term simulated microgravity.     

Perceived effort in sniffing: The effects

Previous research has shown that perceived odor strength does not vary with flow rate of an odorant vapor entering the naris when that variation is produced by subject-controlled changes in sniff pressure, but that it does vary with flow rate when the variation is produced by experimenter-controlled changes in the resistance of the olfactometric system. We have suggested an odor-constancy model in which invariance of perceived odor strength is linked to perceived effort of sniffing, and have hypothesized that changed resistance will have its effect because there is no corresponding change in perceived effort when sniff pressure is held constant. In two studies, subjects made magnitude estimations of the perceived effort of sniffing; sniff pressure was controlled by having the subject match his sniff, displayed on a storage oscilloscope face, to a pattern specifying its required shape, duration, and level. In Experiment 1, resistance was fixed while sniff pressure varied; perceived effort grew as the .8 power of the required sniff pressure. In Experiment 2, sniff pressure and resistance were varied in a factorial design; perceived effort grew as the .8 power of pressure at fixed resistance, but remained unchanged when resistance varied at fixed pressure. This outcome provides indirect support for the odor-constancy model, since it shows that perceived effort covaries with flow rate under the condition in which constancy is found but does not change under the condition in which constancy fails.     

The effects of chronic water deprivation on metabolic rate and long-trace taste-aversion conditioning in rats

The effect of chronic water deprivation on metabolic rate and long-trace taste-aversion conditioning was examined in Wistar-derived rats. Subjects were either maintained on a water deprivation regimen or allowed free access to water for a seven-week period prior to conditioning. At conditioning, rats were presented a saccharin CS followed 0-, 45-, 90-, or 180-min later by an i.p. injection of LiCl. Additionally, pseudo-conditioned groups were presented the CS followed immediately by an injection of physiological saline. Heightened oxygen consumption in deprived subjects suggested that chronic water deprivation increased metabolic rate. While no differences in the amount of saccharin intake were observed at conditioning, percent preference for saccharin scores during a 24-h two-bottle water/saccharin test revealed that non-chronically deprived rats supported conditioning at longer CS-US intervals than did chronically water-deprived rats. Results are interpreted in terms of a time-contraction effect stemming from an alteration of an internal metabolic count-down timer.