The crystal structure of Al20.6Ta22.4 and its relation to Frank–Kasper phases

The monoclinic phase in the Al–Ta system has been identified by means of X-ray single-crystal structure analysis as Al_{19+ x} Ta_{24? x} (x?=?1.6), Pearson symbol mP86. Al_20.58Ta_22.42 crystallizes in the space group P2₁/n, with a?=?987.86?pm, b?=?990.12?pm, c?=?1489.45?pm and β?=?99.958°. Twinned crystals of the title compound can be obtained by iodine-promoted reactions of the elements. In the experiments described here, the reactions took place in sealed tantalum ampoules at 1400°C. Single-phase samples were obtained by a metallurgical powder method, which minimizes aluminium loss by incongruent vapourization. The composition was found to span the range 0.51?≤?x _Ta?≤?0.53. Al_{19+ x} Ta_{24? x} decomposes in the solid state at 1450°C into Al₆₉Ta₃₉ and σ-AlTa₂. The crystal structure is analyzed in relation to tetrahedral close-packed structures. The kinship with Cr₃Si-type and H-type structures is accentuated.     

Accelerating heterogeneous nucleation to increase hardness and electrical conductivity by deformation prior to ageing for Cu-4 at.% Ti alloy

ABSTRACT

Deformation bands, especially shear bands were intentionally formed in supersaturated Cu-4 at.% Ti alloy by groove-rolling with 75% area reduction. Cold deformation prior to the ageing process changed the precipitation behaviour of the alloy. The deformed structure with shear bands was maintained, without showing recovery and recrystallisation, even after prolonged ageing at 450°C for more than one day. The thermally stable shear bands act as nucleation initiation sites and prevent the expansion of discontinuous cellular precipitates. The hardness reached a value of 305?Hv and an electrical conductivity of 15% IACS (IACS?=?International Annealed Copper Standard. 100% IACS is defined as the conductivity corresponding to a volume resistivity at 20°C of 17.241?nΩ), compared to 283?Hv and 13% IACS for conventional solid-solutioned and peak-hardened alloy. In addition, the ageing time to reach the highest hardness was shortened from 720 to 180?min at 450°C.     

J波、fQRS、Tp-ec对ST段抬高性心肌梗死溶栓治疗后恶性心律失常的预测价值

探讨ST段抬高性心肌梗死(STEMI)患者成功溶栓治疗后J波、校正Tp-e间期(Tp-ec)、碎裂QRS波(fQRS)对恶性心律失常事件(MAE)的预测价值及其相关性.选择STEMI患者108例,成功溶栓治疗后随机分为MAE组(29例)和非MAE(NMAE)组(79例),72例正常人的心电图作为对照组.结果示MAE组J波阳性、fQRS阳性、Tp-ec≥100ms显著高于NMAE组(P＜0.05);STEMI患者Tp-ec较对照组显著延长(P＜0.05),经溶栓治疗后,Tp-ec1周和1个月时逐渐恢复,但Tp-ec仍较对照组显著延长(P＜0.05);J波阳性(OR=3.612)、fQRS阳性(OR=2.905)、Tp-ec≥100ms(OR=3.226)(均P＜0.05)与MAE的发生独立相关.以此认为J波、Tp-ec、fQRS和MAE正相关,对溶栓后MAE有预测作用.     

Neurophysiological indices of free recall memory biases in major depression: The impact of stimulus arousal and valence

This study examined differential impact of the valence and arousal characteristics of stimuli on memory biases and brain activity in major depressive disorder (MDD) and non-depressed control participants. P300 and slow wave (SW) components of the event-related brain potential (ERP) were recorded in 18 MDD and 18 control individuals during the encoding of positive and negative, high and low arousal words in a free recall task. Control participants demonstrated expected enhanced memory for positive stimuli that was accompanied by a corresponding increase in SW ERP components. These effects were not seen in the MDD participants. Rather, memory biases for negative information in MDD were only observed for low arousal words and were not reflected in ERP amplitudes. This study suggests that the inconsistency in the MDD memory bias literature may be related to the arousing nature of the stimuli incorporated in the study.     

A RESPONSE TO CARL HELRICH: THE LIMITATIONS AND PROMISE OF QUANTUM THEORY

Abstract. I respond to Carl Helrich's criticism of my proposition that the emergence of complex order in the universe is from Virtual State Actualization (VSA). The question is discussed as to whether quantum theory is able to afford any kind of quantum ontology or whether it merely allows an epistemological view. I point out that, even though many contradictory interpretations of quantum theory are currently possible, the concept of VSA is based on molecular properties that are so simple and factual that they are beyond interpretation. Helrich's appeal for caution in proceeding from physical reality to Divine Reality is wholeheartedly supported and a detailed discussion is given.     

Brain oscillations during semantic evaluation of speech

Changes in oscillatory brain activity have been related to perceptual and cognitive processes such as selective attention and memory matching. Here we examined brain oscillations, measured with electroencephalography (EEG), during a semantic speech processing task that required both lexically mediated memory matching and selective attention. Participants listened to nouns spoken in male and female voices, and detected an animate target (p = 20%) in a train of inanimate standards or vice versa. For a control task, subjects listened to the same words and detected a target male voice in standards of a female voice or vice versa. The standard trials of the semantic task showed enhanced upper beta (25–30 Hz) and gamma band (GBA, 30–60 Hz) activity compared to the voice task. Upper beta and GBA enhancement was accompanied by a suppression of alpha (8–12 Hz) and lower to mid beta (13–20 Hz) activity mainly localized to posterior electrodes. Enhancement of phase-locked theta activity peaking near 275 ms also occurred over the midline electrodes. Theta, upper beta, and gamma band enhancement may reflect lexically mediated template matching in auditory memory, whereas the alpha and beta suppression likely indicate increased attentional processes and memory demands.     

Positive relationship between passive muscle stiffness and rapid force production

We aimed to examine the relationship among the muscle shear modulus at rest, maximal joint torque, and rate of torque development (RTD). Twenty-seven participants (28 ± 5 years, 13 women) were recruited in the study. The cross-sectional area (CSA) of the medial gastrocnemius (MG) muscle belly and shear modulus at an ankle joint angle of 0° were calculated using magnetic resonance imaging and ultrasound shear wave elastography, respectively. Subsequently, participants performed maximal isometric plantar flexion at 0° ankle joint angle [maximal voluntary contraction (MVC) test] as fast and hard as possible (RTD test). RTD was calculated from the time–torque curve over time intervals of 0–30, 0–50, 0–100, 0–150, and 0–200 ms from the onset of plantar flexion during the RTD test and was normalized by MVC torque to exclude muscle strength. MG CSA correlated significantly with MVC torque (r = 0.572), whereas MG shear modulus did not. In contrast, MG shear modulus correlated significantly with normalized RTD at all time intervals (r = 0.460–0.496). These results suggest that passive muscle stiffness is not associated with muscle force; however, higher passive muscle stiffness at a given joint angle may contribute to rapid force production.     

Understanding the shear band interaction in metallic glass

Qualitative and quantitative models were proposed to understand the shear band (SB) interaction scenario found in the compressive tests on specimen with two symmetrical semi-circular notches. The so-called ‘work-hardening’ behavior could be ascribed as the stress interaction which was caused by stress fields around the SB tips. Besides, the SB bending was observed along propagation orientation. The quantitative analysis based on traditional shear deformation mechanism could reasonably account for how the SB was bent. It is anticipated that the present work could provide a pathway to understand the deep SB deformation mechanism of metallic glass.     

心算对内外倾者的心率、T波幅度和呼吸频率的影响

该文旨在探讨内、外倾者在三种不同难度心算时,心率、Ｔ波幅度、呼吸频率变化的差异。通过艾森克个性问卷筛选出１５名内倾者和１５名外倾者作为被试,让其完成三种不同难度的心算任务。实验结果表明,心算时两组被试心率均显著上升,内倾组上升幅度大于外倾组;Ｔ波幅度显著降低,内倾组降低幅度大于外倾组但差异不显著;呼吸频率显著上升,但两组上升幅度差异不显著。此外,从心率变化上看,两组被试对心算均表现出适应,内倾组的适应速度比外倾组慢。本实验表明,焦虑性精神紧张比智力操作性精神紧张对心率的影响更大。