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1.
The thermal stability and glass-forming ability (GFA) of Se80? x Te20Ag x (x?=?0,?3,?5,?7 and 9) chalcogenide glasses have been investigated using differential scanning calorimetry (DSC). The DSC runs have been taken at five different heating rates (10, 20, 30, 40 and 50?K/min) under non-isothermal condition. The thermal stability and GFA are monitored through determination of the temperature difference ΔT?=?T c???T g, where T c is the onset crystallization temperature, T g is the glass transition temperature, H l is the stability parameter, ΔH c is the enthalpy released during crystallization and F i is the fragility index. The activation energy of crystallization E c and crystallization rate factor K have also been determined as indicators of the thermal stability of the above-mentioned samples. It is found that Se71Te20Ag9 is the most stable among all the samples of the series.  相似文献   

2.
Although a large literature demonstrates that object-extracted relative clauses (ORCs) are harder to process than subject-extracted relative clauses (SRCs), there is less agreement regarding where during processing this difficulty emerges, as well as how best to explain these effects. An eye-tracking study by Staub, Dillon, and Clifton (2017) demonstrated that readers experience more processing difficulty at the matrix verb for ORCs than for SRCs when the matrix verb immediately follows the relative clause (RC), but the difficulty is eliminated if a prepositional phrase (PP) intervenes. A careful examination of Staub et al.’s materials reveals that the types of PPs used in the experiment were a mixture of locative and temporal PPs. This is important in that locative PPs can modify either a noun phrase or a verb phrase (VP), whereas temporal PPs typically modify VPs, resulting in systematic differences in PP attachment across ORCs versus SRCs. In the current eye-tracking experiment, we systematically manipulated RC type and PP type in the same sentences used by Staub et al. The manipulation of PP type resulted in a crossover pattern at the matrix verb such that there was a trend for reading times to be longer for ORCs than SRCs when the PP was locative, but reading times were longer for SRCs than ORCs when the PP was temporal. These results provide important information regarding the locus of RC-processing effects and highlight the importance of carefully considering how intervening material might unintentionally alter the structure or the meaning of a sentence.  相似文献   

3.
Differential scanning calorimetry (DSC) has been used to study the crystallization kinetics of glassy Se98In2 both before and after irradiation of the alloy with high-energy (50 MeV) lithium ions. After the ion-irradiation, significant changes in the kinetic parameters of crystallization of the glass were observed. The results are explained in terms of a model involving irradiation-induced defects.  相似文献   

4.

The microstructure and crystallization behaviour of melt-spun Al88Ni9Ce2Fe1 amorphous alloy and nanophase composites have been studied by means of X-ray diffraction, transmission electron microscopy and scanning and isothermal calorimetry. The diffraction patterns from Al88Ni9Ce2Fe1 amorphous alloys are diffuse, indicating a basically amorphous structure but contain two rings presumed to be associated with quenched-in nuclei. In the cases of Al88Ni9Ce2Fe1 nanophase composites, nanoscale precipitated particles are homogeneously dispersed in an amorphous matrix, and the crystallite diameter and volume fraction are sensitive to quenching conditions. During thermal crystallization, a two-step phase transformation occurs in the amorphous alloy and nanocomposites, which is characterized by a diffusion-controlled precipitation of nanoscale Al particles and the growth of a Al3(Ni, Fe) nanophase prior to a Al11Ce3 nanophase. This study gives insight into structure-control for obtaining nanophases dispersed in an amorphous matrix by rapid quenching.  相似文献   

5.

The first stages of thermal relaxation towards equilibrium in a Zr 57 Ti 5 Cu 20 Al 10 Ni 8 bulk metallic glass have been studied by differential scanning calorimetry, X-ray diffraction, transmission electron microscopy and high-resolution electron microscopy. These coupled experiments rule out for this glass the existence of a phase separation on the nanometric scale preceding the onset of crystallization. The first step of crystallization is of the primary type, that is it consists of the nucleation of nanocrystallites in the amorphous matrix with which they coexist in metastable equilibrium. The very high nucleation rate leads to a nanometric composite structure with a number density of about 7 2 10 24 m -3 of 3-4nm crystallites, occupying a volume fraction of about 15%. These features, as well as the crystallization kinetics observed during isochronal or isothermal heating, are discussed.  相似文献   

6.
Event-related potential correlates of positive priming (PP) and negative priming (NP) were investigated in order to further elucidate the cognitive mechanisms involved. Thirty-six participants performed both an identity- and a location-based priming task. Repeating the target stimulus/location from the immediately preceding display produced behavioral PP. With localization, but not with identification, behavioral NP was observed when the target stimulus/location matched the preceding distractor stimulus/location. Smaller P300 amplitude accompanied identity-based PP, suggesting persisting target-specific activation. The lateralized readiness potential, an index of correct/incorrect response activation, indicated persisting central motor activation as another source of PP. Both location-based PP and NP were accompanied by reduced P1/N1 and P300 amplitudes, pointing to the involvement of inhibition of return in location-based priming. The results support the view that multiple brain processes underlie behavioral priming.  相似文献   

7.
《ARCS兴趣问卷》的编制   总被引:6,自引:0,他引:6       下载免费PDF全文
本研究以凯勒的“ARCS模型”作为理论基础,以“激励策略”作为载体和表现形式。经过开放式调查以及对教师和学生的访谈,编制了《ARCS兴趣问卷》。被试是北京师范大学附属实验小学4、5年级8个班的349名学生,施测了《ARCS兴趣问卷》。对4年级的4个班还施测了《IMMS》和《CIE&CES》问卷。对《ARCS兴趣问卷》的项目进行了筛选和修订,最后保留49条项目。对《ARCS兴趣问卷》的信度和效度进行了考察,总体来看,问卷的信度和效度都比较好。研究表明注意与切身性相关,自信心与满意相关。  相似文献   

8.
Neodymium-doped silica nanocomposites were prepared from an acid-catalysed sol–gel solution followed by heat treatment. The structural and microstructural properties of the prepared samples as a function of sintering temperature and Nd concentration are reported. Fourier transform infrared spectra show that phase separation occurs during heat treatment. The presence of Nd2O3 and α-Nd2Si2O7 phases in the samples was established by X-ray diffraction (XRD), and transmission electron microscopy (TEM) micrographs revealed the microstructure of the nanocomposites. From XRD patterns, the crystallite size was determined using the Debye–Scherrer formula, while the particle size was estimated from TEM micrographs. The results suggest that sintering at high temperature enhances the crystallinity and density of Nd2O3–SiO2 nanocomposites, while the high concentration of neodymium prevents the crystallization of SiO2.  相似文献   

9.
We report high-yield synthesis of selenium, silver and silver–selenide nanocrystallites (Ag2Se) in an amorphous matrix of Se98Ag2 alloy. The method avoids the necessity of exotic chemicals, high temperatures and high pressures, and requires only a few seconds of laser exposure (~30?s). The amorphous Se98Ag2 alloy is first synthesized by the conventional and cost-effective melt-quenching technique. Then, laser-induced crystallization was performed using a Nd:YVO4 laser. The morphology and microstructure of the obtained nanocrystallites have been analysed by DSC, XRD and SEM.  相似文献   

10.
ABSTRACT

Unlike previous studies, the present experiment was designed to directly compare negative (NP) and positive priming (PP) in 37 young (mean age: 21.5 years) and 37 older adults (mean age: 69.4 years) by means of two independent identity- and location-based priming tasks. While identity PP was shown to be reduced in older adults, no age-related differences were found for location PP. This pattern of results supports the notion that mechanisms involved in identity- and location-based PP are largely independent of each other. Both age groups exhibited reliable identity and location NP although location NP was decreased in older adults. Extremely low temporal test–retest coefficients indicated that mechanisms underlying identity and location NP represent situational states rather than stable traits. This lack of temporal stability may also account for highly ambiguous results obtained in previous studies.  相似文献   

11.
To explore the relationship between parental phubbing (PP) and adolescent online hostility and its' psychological mechanism, 689 Chinese adolescents were recruited to complete a paper-and-pencil questionnaire. We took cyber flaming (CF) as an overall category for hostile online communication to investigate the relationship between PP and CF and the mediating role of perspective-taking (PT) in this relationship and examined whether there is a sex difference in this process. After controlling the average daily online time, the results showed that PP predicted adolescent CF positively. The relationship between PP and CF was partially mediated by PT. The effect of PP on PT was moderated by sex, with the result being significant only for boys. Related findings and future directions were discussed.  相似文献   

12.

Thermomagnetic measurements have been used to study the magnetic and structural changes occurring at the two steps of the crystallization process of Fe73.5Si13.5B9Cu1Nb1X2 (X = Zr, Nb, Mo and V) alloys. Alloying raises the thermal stability of the amorphous phase against nanocrystallization in the order V < Mo < Nb < Zr and some differences in the final crystalline phases are found. The Curie temperature of the amorphous phase increases (about 15K) during structural relaxation. In the course of nanocrystallization a further increase of about 30K in the Curie temperature of the amorphous intergranular is observed for samples with X = Zr, Nb and Mo, but only of about 15K for samples containing V. The observed increase in the Curie temperature of the Fe-Si phase between the end of the first crystallization process and the end of the second crystallization process is associated with a reduction in the Si content, in agreement with X-ray diffraction results.  相似文献   

13.
In an eyetracking experiment, participants read sentences that contained a prepositional phrase (PP) that could be attached to one of two preceding verbs. To understand the sentence, readers had to select which verb would serve as the host for the PP. In some of the sentences, the critical verbs and the PPs were part of a subordinate clause in which lexical and syntactic factors were expected to matter, but discourse factors favoring attachment of the material to positions where it would be relevant to the main assertion of the sentence were not expected to matter. In other sentences, the critical material was tested in main clause contexts in which the main assertion principle was predicted to apply. Hierarchical linear modeling showed that online attachment preferences were affected by clause type (main vs. subordinate). Specifically, the preference for a local verb over a distant verb was greater when the critical material appeared within a subordinate clause than when it appeared within a main clause. This pattern of results can be explained by the operation of the relativized relevance or main assertion principle, which in our sentences meant that participants favored attachment of the PP to the first verb over the second.  相似文献   

14.
ABSTRACT

Poly(methyl methacrylate) films and poly(methyl methacrylate)/fullerene composite films were fabricated by casting from toluene solutions. The mass fraction of fullerene (C60) was varied from 0.05–3?wt. %. The effect of the fullerene (C60) content on the thermal degradation parameters of the composite films was evaluated by thermogravimetric (TG) analysis. It was found that the incorporation of C60 improved the thermal stability of the polymers. The films eventually decomposed in three stages. Incorporation of fullerene caused a change in the distribution of mass loss over the stages of degradation in comparison with the pristine polymer. Using differential scanning calorimetry (DSC), the phase transitions from the glassy state to the elastic one was studied for the examined polymeric materials. New data relating to the effect of C60 on the glass transition temperature of composites with low weight fractions of filler were obtained. Specifically, for films containing up to 0.1 wt. % of C60, a single glass transition temperature was found, whereas for composites with a higher concentration of filler, two glass transition temperatures were recorded.  相似文献   

15.
Data in psychology are often collected using Likert‐type scales, and it has been shown that factor analysis of Likert‐type data is better performed on the polychoric correlation matrix than on the product‐moment covariance matrix, especially when the distributions of the observed variables are skewed. In theory, factor analysis of the polychoric correlation matrix is best conducted using generalized least squares with an asymptotically correct weight matrix (AGLS). However, simulation studies showed that both least squares (LS) and diagonally weighted least squares (DWLS) perform better than AGLS, and thus LS or DWLS is routinely used in practice. In either LS or DWLS, the associations among the polychoric correlation coefficients are completely ignored. To mend such a gap between statistical theory and empirical work, this paper proposes new methods, called ridge GLS, for factor analysis of ordinal data. Monte Carlo results show that, for a wide range of sample sizes, ridge GLS methods yield uniformly more accurate parameter estimates than existing methods (LS, DWLS, AGLS). A real‐data example indicates that estimates by ridge GLS are 9–20% more efficient than those by existing methods. Rescaled and adjusted test statistics as well as sandwich‐type standard errors following the ridge GLS methods also perform reasonably well.  相似文献   

16.
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.  相似文献   

17.
The current study examined interactive effects among personality and job stressors in predicting employees' engagement in counterproductive work behavior (CWB) defined as behavior that harms organizations or people in organizations. Survey data were collected from 932 employees and results showed significant negative relationships of agreeableness, conscientiousness, and emotional stability with CWB directed at organizations (CWB‐O) and people (CWB‐P), and significant positive relationships of interpersonal conflict and organizational constraints with CWB‐O and CWB‐P. Further, it was found that the positive relationships of interpersonal conflict with CWB‐O and CWB‐P were strongest for people of low emotional stability–low agreeableness among all emotional stability–agreeableness combinations, and that the positive relationships of organizational constraints with CWB‐O and CWB‐P were strongest for people of high emotional stability–low conscientiousness among all emotional stability–conscientiousness combinations.  相似文献   

18.
Acquisition of gross motor sequence learning with physical and mental training elicits gains in performance. However, the effects of sleep or daytime consolidation after both types of practice remain unclear, especially the effects upon the goal- and movement-based components of a gross motor sequential task. The main purpose of this study was to test the effect of physical practice (PP) and motor imagery practice (MIP) on the acquisition and consolidation processes of gross motor sequence learning.Seventy-six participants were tested before and after PP or MIP on a whole-body sequential paradigm, following either a night of sleep (PPsleep and MIPsleep groups) or an equivalent daytime period (PPday and MIPday groups). Control groups without training were tested following similar timespans (CTRLsleep and CTRLday groups). The number of sequential movements and the centre of mass displacement – corresponding to goal and movement-based components, respectively – were assessed.Results showed that relative to the CTRL groups, the PP and MIP groups improved performance during acquisition. Importantly, only the MIPsleep group further improved performance after a night of sleep; participants of other groups stabilised their performance after consolidation. Additionally, the number of sequential movements and the centre of mass displacement evolved conjointly without being influenced by the type of training or the nature of the consolidation.To conclude, these results confirm that sleep contributes to the consolidation of gross motor sequence learning acquired with MIP but not PP. The relationship between the goal- and movement-based components of a gross motor sequential task is discussed.  相似文献   

19.
The dominant error types were investigated as a function of phonological processing (PP) deficit severity in four groups of impaired readers. For this aim, an error analysis paradigm distinguishing between four error types was used. The findings revealed that the different types of impaired readers were characterized by differing predominant error types. The dysphonetic errors predominated in readers with severe PP deficit and the morphological errors predominated in those with moderate deficits. Finally, readers with attention difficulties showed a predominance of semiphonetic errors. These findings were discussed in relation to reading disability subtypes and their clinical implications.  相似文献   

20.
The glass-forming ability of Ge1? x Sn x Se2.5 (0 ≤ x ≤ 0.5) alloys was studied using differential scanning calorimetry. Samples were scanned at different heating rates under non-isothermal conditions. Various simple quantitative methods were employed to assess the stability of the glassy materials in the above-mentioned system. All of these methods are based on characteristic temperatures, such as the glass-transition temperature, T g, the onset-of-crystallization temperature, T c, and the peak crystallization temperature, T p. A crystallization rate factor, K, has also been used as a measure of the thermal stability of the glasses. It was found that Ge0.7Sn0.3Se2.5 was the least stable among all the samples.  相似文献   

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