scholarly journals Features of the synthesis of highly dispersed alumophosphates AlPO4·nH2O

2021 ◽  
Vol 57 (3) ◽  
pp. 310-319
Author(s):  
L. S. Eshchenko ◽  
A. V. Paniatouski
Keyword(s):  
Particle Size ◽  
Hydrothermal Treatment ◽  
Monoclinic Structure ◽  
Entire Volume ◽  
Prolonged Heating ◽  
Temperature Range ◽  
Crystalline Product ◽  
Primary Particles ◽  
First Time

Aluminum orthophosphate of the composition AlPO4·2H2O with a monoclinic structure identical to the structure of the natural mineral metavariscite was obtained by condensation method during hydrothermal treatment of alumophosphate solutions with a concentration (g/l) of Al2O3 90 – 115, P2O5 340 – 440 in the temperature range 95–99 °C. For the first time, the role of aging of the alumophosphate system in shortening of the induction period, simultaneous nucleation of primary particles in the entire volume of the solution and the formation of a pasty product with a predominant particle size of 1–10 μm, in contrast to 30–50 μm, characteristic of a fine-crystalline product obtained without aging of the solution, is established. It is shown that pasty AlPO4·2H2O, in comparison with fine-crystalline, is hardly soluble in HCl even under prolonged heating. The influence of P2O5 content in the alumophosphate solution, the conditions of its aging and the duration of hydrothermal treatment on the particle size distribution for synthesized aluminum orthophosphates have been established. Anhydrous alumophosphate obtained by dehydration of pasty AlPO4·2H2O in the temperature range of 150–200 °C with subsequent heat treatment at 900 °C is readily soluble in acids, and the predominant particle size is 5–13 μm.

Dislocations and the thermal reactivity of calcite

1970 ◽  
Vol 314 (1518) ◽  
pp. 429-441 ◽  
Keyword(s):  
Chemical Reactivity ◽  
Previous History ◽  
Strain Fields ◽  
Temperature Range ◽  
Reactivity Of Solids ◽  
Dislocation Movement ◽  
History Of ◽  
First Time ◽  
Kinetics Of

A study has been made of the effect of dislocation movement on the kinetics of thermal decomposition of freshly cleaved calcite crystals. It is shown for the first time that the thermal history of the crystal has a marked effect on its reactivity and two patterns of behaviour have been identified; that in the temperature range up to ca . 700 K in which the kinetics of decomposition are sensitively dependent upon the nature and extent of the crystal’s previous history, and the range above 700 K in which annealing is rapid and reproducible kinetics are obtained for all crystals studied. This effect has not been observed in previous studies of calcite. It is suggested that this is because the experiments were carried out in the temperature range where movement of dislocations is so rapid that the surface structure is virtually constant during the measurements. Tentative correlations are made between the various stages of the observed rates of decomposition and the known dislocation systems in the crystal. The influence of applied stress was studied but because of limitations in the method of stressing the crystal, the amount of plastic deformation was small and its effect on reactivity was not marked. Qualitative consideration is given to the role of dislocations in the reactivity of solids and it is concluded that the elastic energy associated with the strain fields around or at the core of the dislocation cannot be used to promote chemical reactivity but that it is the change in the stereochemical environment of molecules in the dislocated region of the crystal which is important. ‘ . . . a curious illustration of the influence of mechanical forces over chemical affinity. . . ’ M. Faraday (1834)

Discrete angle rotations of Bi nanoparticles embedded in a Ga matrix

Open Physics ◽  
2010 ◽  
Vol 8 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Avraham Be’er ◽  
Richard Kofman ◽  
Yossi Lereah
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Time Resolved ◽  
Transmission Electron ◽  
The Difference ◽  
First Time ◽  
Microscopy Images ◽  
Bi Nanoparticles

AbstractSpontaneous instabilities of nanoparticles are known to be influenced by the temperature, and strongly depend on the particle size. However, it is not clear what is the role of the surrounding material that is in contact with the particle. Here we report on the difference between spontaneous rotations of Bi nanoparticles embedded in amorphous SiO and those embedded in liquid Ga. The phenomenon was studied quantitatively by time resolved transmission electron microscopy using Fourier Transform analysis of highresolution electron microscopy images. While rotations of Bi nanoparticles embedded in amorphous SiO occur by all angles, the rotations of Bi nanoparticles embedded in liquid Ga occur by discrete angles. Our results point quantitatively, for the first time, to the role and importance of the contacting surrounding surface during the rotation of nanoparticles.

On Polymorphism of Dysprosium Trichloride

2015 ◽  
Vol 70 (3) ◽  
pp. 153-157 ◽  
Author(s):  
Irina D. Zakirýanova ◽  
Vladimir A. Khokhlov ◽  
Alexander B. Salyulev ◽  
Iraida V. Korzun
Keyword(s):  
Mass Spectrometry ◽  
Spectroscopic Data ◽  
Polymorphic Transformation ◽  
Room Temperature ◽  
Monoclinic Structure ◽  
Phonon Modes ◽  
Monoclinic Crystal ◽  
Raman Spectroscopic ◽  
Temperature Range ◽  
First Time

AbstractFor the first time, the structure of crystalline DyCl3 over a wide temperature range from room temperature to melting point was studied by Raman spectroscopy. The phonon modes (cm–1) of dysprosium trichloride (monoclinic crystal lattice of AlCl3 type, Z=4, CN = 6) at room temperature are 257 (A1g), 201 (Eg), 112 (Eg), 88 (A1g), and 63 (Eg). The monoclinic structure of the crystalline DyCl3 C2h3 symmetry was found to remain constant over the studied temperature range. No polymorphic transformation in the solid state was detected. Gravimetry, calorimetry, and mass spectrometry have been used in addition to support the conclusions made on the basis of Raman spectroscopic data.

scholarly journals Role of crystal size on swing-effect and adsorption induced structure transition of ZIF-8

2016 ◽  
Vol 45 (16) ◽  
pp. 6893-6900 ◽  
Author(s):  
Tian Tian ◽  
Michael T. Wharmby ◽  
José B. Parra ◽  
Conchi O. Ania ◽  
David Fairen-Jimenez
Keyword(s):  
Particle Size ◽  
Crystal Size ◽  
Gas Adsorption ◽  
Rietveld Analysis ◽  
Structure Transition ◽  
First Time ◽  
Induced Structure ◽  
Transition Behaviour

The flexibility and structure transition behaviour of ZIF-8 in a series of samples with different particle size has been studied using a combination of high-resolution N2 gas adsorption isotherms and, for the first time, a broad in situ PXRD and Rietveld analysis.

Psychological Resilience Provides No Independent Protection From Suicidal Risk

Crisis ◽  
2016 ◽  
Vol 37 (2) ◽  
pp. 130-139 ◽  
Author(s):  
Danica W. Y. Liu ◽  
A. Kate Fairweather-Schmidt ◽  
Richard Burns ◽  
Rachel M. Roberts ◽  
Kaarin J. Anstey
Keyword(s):  
Risk Factors ◽  
Well Being ◽  
Current Status ◽  
Psychological Resilience ◽  
Cross Sectional ◽  
Life Project ◽  
Resilience Factors ◽  
First Time

Abstract. Background: Little is known about the role of resilience in the likelihood of suicidal ideation (SI) over time. Aims: We examined the association between resilience and SI in a young-adult cohort over 4 years. Our objectives were to determine whether resilience was associated with SI at follow-up or, conversely, whether SI was associated with lowered resilience at follow-up. Method: Participants were selected from the Personality and Total Health (PATH) Through Life Project from Canberra and Queanbeyan, Australia, aged 28–32 years at the first time point and 32–36 at the second. Multinomial, linear, and binary regression analyses explored the association between resilience and SI over two time points. Models were adjusted for suicidality risk factors. Results: While unadjusted analyses identified associations between resilience and SI, these effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.

Fibrin Formation: The Role of the Fibrinogen-Fibrin Monomer Complex

1976 ◽  
Vol 36 (01) ◽  
pp. 037-048 ◽  
Author(s):  
Eric P. Brass ◽  
Walter B. Forman ◽  
Robert V. Edwards ◽  
Olgierd Lindan
Keyword(s):  
Particle Size ◽  
Induction Period ◽  
Fibrin Clot ◽  
Clot Formation ◽  
Appreciable Amount ◽  
Buffer System ◽  
Homeostatic Mechanism ◽  
Fibrin Formation ◽  
Fibrin Monomer

SummaryThe process of fibrin formation using highly purified fibrinogen and thrombin was studied using laser fluctuation spectroscopy, a method that rapidly determines particle size in a solution. Two periods in fibrin clot formation were noted: an induction period during which no fibrin polymerization occurred and a period of rapid increase in particle size. Direct measurement of fibrin monomer polymerization and fibrinopeptide release showed no evidence of an induction period. These observations were best explained by a kinetic model for fibrin clot formation incorporating a reversible fibrinogen-fibrin monomer complex. In this model, the complex serves as a buffer system during the earliest phase of fibrin formation. This prevents the accumulation of free polymerizable fibrin monomer until an appreciable amount of fibrinogen has reacted with thrombin, at which point the fibrin monomer level rises rapidly and polymerization proceeds. Clinically, the complex may be a homeostatic mechanism preventing pathological clotting during periods of elevated fibrinogen.

Synergetic Theory of Document in Evolution of Document Science

2018 ◽  
pp. 1060-1068
Author(s):  
Galina A. Dvoenosova ◽  
Keyword(s):  
Social Role ◽  
Scientific Study ◽  
Self Organization ◽  
Universal Theory ◽  
Social Self ◽  
Social Goal ◽  
The Social ◽  
Synergetic Theory ◽  
First Time

The article assesses synergetic theory of document as a new development in document science. In information society the social role of document grows, as information involves all members of society in the process of documentation. The transformation of document under the influence of modern information technologies increases its interest to representatives of different sciences. Interdisciplinary nature of document as an object of research leads to an ambiguous interpretation of its nature and social role. The article expresses and contends the author's views on this issue. In her opinion, social role of document is incidental to its being a main social tool regulating the life of civilized society. Thus, the study aims to create a scientific theory of document, explaining its nature and social role as a tool of social (goal-oriented) action and social self-organization. Substantiation of this idea is based on application of synergetics (i.e., universal theory of self-organization) to scientific study of document. In the synergetic paradigm, social and historical development is seen as the change of phases of chaos and order, and document is considered a main tool that regulates social relations. Unlike other theories of document, synergetic theory studies document not as a carrier and means of information transfer, but as a unique social phenomenon and universal social tool. For the first time, the study of document steps out of traditional frameworks of office, archive, and library. The document is placed on the scales with society as a global social system with its functional subsystems of politics, economy, culture, and personality. For the first time, the methods of social sciences and modern sociological theories are applied to scientific study of document. This methodology provided a basis for theoretical vindication of nature and social role of document as a tool of social (goal-oriented) action and social self-organization. The study frames a synergetic theory of document with methodological foundations and basic concepts, synergetic model of document, laws of development and effectiveness of document in the social continuum. At the present stage of development of science, it can be considered the highest form of theoretical knowledge of document and its scientific explanatory theory.

Physical Warmth Attenuates Ethnocentric Bias under Mortality Salience: An Embodied Terror Management Perspective

2020 ◽  
Author(s):  
Armand Chatard ◽  
Margaux Renoux ◽  
Jean Monéger ◽  
Leila Selimbegovic
Keyword(s):  
Mortality Salience ◽  
Terror Management ◽  
Negative Consequences ◽  
Defensive Reaction ◽  
Worldview Defense ◽  
Management Perspective ◽  
Physical Warmth ◽  
Alternative Means ◽  
First Time

Research indicates that individuals often deal with mortality salience by affirming beliefs in national or cultural superiority (worldview defense). Because worldview defense may be associated with negative consequences (discrimination), it is important to identify alternative means to deal with death-related thoughts. In line with an embodied terror management perspective, we evaluate for the first time the role of physical warmth in reducing defensive reaction to mortality salience. We predicted that, like social affiliation (social warmth), physical warmth could reduce worldview defense when mortality is salient. In this exploratory (preregistered) study, 202 French participants were primed with death-related thoughts, or an aversive control topic, in a heated room or a non-heated room. The main outcome was worldview defense (ethnocentric bias). We found no main effect of mortality salience on worldview defense. However, physical warmth reduced worldview defense when mortality was salient. Implications for an embodied terror management perspective are discussed.

Relationship between big five personality model and abusive supervision

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Bibi Tahira ◽  
Naveed Saif ◽  
Muhammad Haroon ◽  
Sadaqat Ali
Keyword(s):  
Big Five ◽  
Abusive Supervision ◽  
State Universities ◽  
Big Five Personality ◽  
Big Five Model ◽  
The Impact ◽  
First Time ◽  
Supervisor Behavior ◽  
Moderating Role

The current study tries to understand the diverse nature of relationship between personality Big Five Model (PBFM) and student's perception of abusive supervision in higher education institutions of Khyber Pakhtoonkhwa Pakistan. Data was collected in dyads i.e. (supervisors were asked to rate their personality attributes while student were asked to rate the supervisor behavior) through adopted construct. For this purpose, data was collected from three government state universities and one Private Sector University. The focus was on MS/M.Phill and PhD student and their supervisors of the mentioned universities. After measuring normality and validity regression analysis was conducted to assess the impact of supervisor personality characteristics that leads to abusive supervision. Findings indicate interestingly that except agreeableness other four attributes of (PBFM) are play their role for abusive supervision. The results are novel in the nature as for the first time Neuroticism, openness to experience, extraversion and conscientiousness are held responsible for the abusive supervision. The study did not explore the demographic characteristics, and moderating role of organizational culture, justice and interpersonal deviances to understand the strength of relationship in more detail way. Keywords: Personality big five model, abusive supervision, HEIs

Sign in / Sign up

Export Citation Format

Share Document