scholarly journals Spectroscopic and Thermal Analyses of Ortho-Benzylphenol Crystalline Polymorphism

2018 ◽  
Vol 63 (2) ◽  
pp. 95 ◽  
Author(s):  
J. Baran ◽  
N. A. Davydova ◽  
M. Drozd ◽  
E. A. Ponezha ◽  
V. Ya. Reznichenko

In situ, we present the experimental spectroscopic proof of the existence of polymorphism in ortho-benzylphenol. Infrared spectroscopy was used for the first time to investigate the structural changes during the crystallization of a metastable phase, which is transformed, in the course of time, into a stable one. The results show that, in the stable and metastable phases, different conformers of ortho-benzylphenol molecule predominate, which differ in the orientation of the aromatic rings relative to the connecting methylene bridge. Namely, it is shown that the transformation of the metastable phase into a stable one is accompanied by the rotation of the OH-substituted aromatic ring relative to the connecting methylene bridge from 59.9∘ to 180.0∘ in the molecule of ortho-benzylphenol. The DSC experiment has shown that the process of nucleation of a metastable phase preferentially develops below ∼1.1 Tg (243 K), the crystallization occurs at ∼272 K, and the melting happens at 290.2 K. The difference in the temperature regions of nucleation and crystallization explains a good glass-forming status of ortho-benzylphenol.

1991 ◽  
Vol 235 ◽  
Author(s):  
S. L. Lai ◽  
Z. J. Zhang ◽  
J. R. Ding ◽  
B. X. Liu

ABSTRACTAmorphization behavior was studied for the Y-Ti system, which has rather positive heat of formation being around + 22 kJ/mol, by room temperature 360 keV xenon ion mixing of YxTi100−xmultilayered films to various doses, ranging from 7×1014 to 1×1016 xe/cm2 Single and uniform amorphous phase was obtained in a narrow composition region, i.e. x=65 to 75, after ion mixing to the relevant doses. Moreover, a metastable fee crystalline Y-Ti phase was observed, for the first time, in this system. The crystalline lattice constant of the metastable phase was determined to be 4.012 Å. The re-crystallization temperature of the formed amorphous alloy was found out to be 600°C by in situ transmission electron microscope annealing as well as by vacuum furnace experiments. Possible interpretation is also discussed by comparing the experimental results with those proposed models for predicting glass forming ability.


1991 ◽  
Vol 230 ◽  
Author(s):  
J. B. Rubin ◽  
R. B. Schwarz

AbstractWe determine the glass forming range (GFR) of co-deposited Ni1−xZrx (0 < x < 1) thin films by measuring their electrical resistance during in situ constant-heating-rate anneals. The measured GFR is continuous for 0.10 < x < 0.87. We calculate the GFR of Ni-Zr melts as a function of composition and cooling rate using homogeneous nucleation theory and a published CALPHAD-type thermodynamic modeling of the equilibrium phase diagram. Assuming that the main competition to the retention of the amorphous structure during the cooling of the liquid comes from the partitionless crystallization of the terminal solid solutions, we calculate that for dT/dt = 1012 K s−1, the GFR extends to x = 0.05 and x = 0.96. Better agreement with the measured values is obtained assuming a lower ‘effective’ cooling rate during the condensation of the films.


2020 ◽  
Vol 27 (6) ◽  
pp. 1640-1647
Author(s):  
Takafumi Miyanaga ◽  
Yushi Suzuki ◽  
Sho Narita ◽  
Reki Nakamura

The in situ X-ray absorption fine structure (XAFS) for the structural changes of Ag clusters produced in the cavity of luminescent zeolites by thermal treatment of Ag zeolite-A and Ag zeolite-X has been studied. The following procedures are compared: (i) samples are heated and cooled to room temperature under atmosphere (under air); (ii) samples are heated and cooled to room temperature in a vacuum and then exposed to air. It was confirmed that the Ag clusters were broken when the Ag zeolite was exposed to air for Ag zeolite-X, which complements our previous results for Ag12-A. It is suggested that the deformation of the Ag clusters plays an important role in the generation of a strong photoluminescence band, and Ag clusters may not be direct species producing the strong photoluminescence. The local structure of the Ag ions was found to be slightly different from that of the unheated species. The difference may originate from the formation and breakdown of Ag clusters in the zeolite cavity.


Author(s):  
Kazuki Komatsu ◽  
Ayako Shinozaki ◽  
Shinichi Machida ◽  
Takuto Matsubayashi ◽  
Mao Watanabe ◽  
...  

Magnesium dichloride decahydrate (MgCl2·10H2O) and its deuterated counterpart (MgCl2·10D2O) are identified for the first time byin-situpowder synchrotron X-ray and spallation neutron diffraction. These substances are crystallized from a previously unidentified nanocrystalline compound, which originates from an amorphous state at low temperature. A combination of a recently developed autoindexing procedure and the charge-flipping method reveals that the crystal structure of MgCl2·10H2O consists of an ABCABC... sequence of Mg(H2O)6octahedra. The Cl−anions and remaining water molecules unconnected to the Mg2+cations bind the octahedra, similar to other water-rich magnesium dichloride hydrates. The D positions in MgCl2·10D2O, determined by the difference Fourier methods using the neutron powder diffraction patterns at 2.5 GPa, show the features such as bifurcated hydrogen bonds and tetrahedrally coordinated O atoms, which were not found in other forms of magnesium chloride hydrates.


2019 ◽  
pp. 46-65
Author(s):  
Е. В. Качуров ◽  
С. В. Качурова

The article, for the first time ever, considers the phenomenon of the emergence and historical development of ideology, up to the full realization of this process. Some scientists call this moment of completion as «crisis», the others – as «doom». Considering one essential feature of modern ideology, we call it a «default». We are talking about its voluntary commitment to replace the philosophical knowledge that traditionally provided the European history of previous eras.To understand this phenomenon, the fact of the relationship between ideology and phenomenology is defined as a matter of principle, which almost completely coincides with it in its subject matter. Both are engaged in consciousness. The nuances of their differences are rooted in the difference of theoretical and practical horizons.Having raised the question of the emergence of ideology, the work comes to the conclusion that its cause is the classical German phenomenology (from Kant to Hegel). The same kinds of phenomenology that were created by ideology itself in the nineteenth and twentieth centuries have a qualitatively different character. All of them come from the «conditioning of consciousness by being», while the philosophical classics sought to «mediate consciousness as an object, with consciousness as a method». Such a sharp deviation of the various theories of knowledge of the last two centuries was caused exclusively by the practical orientation of ideological consciousness.The use of the «crime novel» form in the article, which is indicated by both the researchers of the «false consciousness» and the researchers of phenomenology, made it possible to trace their interaction in dynamics. By exposing each other, ideologies «dragged» their own phenomenologies into this trial, which, in turn, unwittingly, were eventually forced to take the path of de-idealizing their own origins. So the course of this struggle has undergone significant changes in both phenomena.The article for the first time considers its «naive», «political» and «cynical» forms as the stages of the development of ideology. Variants of the idea of a «consciousness that does not know what is happening behind its back» by G. Hegel, the concepts of K. Marx’s «illusory consciousness» and P. Sloterdijk’s theory of the «enlightened false consciousness» here serve as markers for distinguishing these stages.As a result, it is stated that the default of modern ideologies in a positive way led to structural changes in the classical model of philosophical knowledge. Modern forms of phenomenology began to return to it, but in an updated form. The knowledge of positive sciences, which was previously included in all the historical systems of philosophy, is now excluded from it, and logic, history of philosophy and classical phenomenology, with a stable moment of de-ideologization of all types of false consciousness, become its main task.


2019 ◽  
Author(s):  
Mai Ouchi ◽  
Yutaka Matsumi ◽  
Tomoki Nakayama ◽  
Kensaku Shimizu ◽  
Takehiko Sawada ◽  
...  

Abstract. A novel, practical observation system for measuring tropospheric carbon dioxide (CO2) concentrations using a non-dispersive infrared analyzer carried by a small helium-filled balloon (CO2 sonde), has been developed for the first time. Onboard calibrations, using CO2 standard gases, is possible to measure the vertical profiles of atmospheric CO2 accurately with a 240–400 m altitude resolution. The standard deviations (1σ) of the measured mixing ratios in the laboratory experiments using a vacuum chamber at a temperature of 298 K were approximately 0.6 ppm at 1010 hPa and 1.2 ppm at 250 hPa. Compared with in situ aircraft data, although the difference up to the altitude of 7 km was 0.6 ± 1.2 ppm, this bias and difference were within the precision of the CO2 sonde. In field experiments, the CO2 sonde detected an increase in CO2 concentration in an urban area and a decrease in a forested area near the surface. The CO2 sonde was shown to be a useful instrument for observing and monitoring the vertical profiles of CO2 concentration in the troposphere.


2015 ◽  
Vol 51 (25) ◽  
pp. 5509-5512 ◽  
Author(s):  
Rico F. Tabor ◽  
Matthew J. Pottage ◽  
Christopher J. Garvey ◽  
Brendan L. Wilkinson

We report the light-induced structural evolution of photoswitchable carbohydrate-based surfactant micelles using time-resolved small-angle neutron scattering (TR-SANS), monitoring the structural changes in micellisation in situ over time and demonstrating for the first time the course and implications of this process.


Parasitology ◽  
1920 ◽  
Vol 12 (1) ◽  
pp. 1-6 ◽  
Author(s):  
George H. F. Nuttall

The coloration of Amblyomma hebraeum, A. gemma, Dermacentor venustus, D. variabilis and D. reticulatus niveus, as seen in living examples, is depicted for the first time, and the desirability of recording the colours of ornate ticks when alive is indicated.A remarkable change in colour in living specimens of A. hebraeum is described and figured, this change taking place after a prolonged sojourn (74–141 days) upon the host. Such a colour change has not hitherto been observed in ticks. The difference in colour is seen in dead dried specimens but is not appreciable in those preserved in alcohol.Since the immature stages of ornate ticks are inornate, and the colours change in adults of some species during prolonged periods of parasitism, it is evident that the coloration in adults must depend upon the accumulated products of metabolism beneath the chitinous exoskeleton, the regional distribution of colour depending upon special metabolic functions taking place in corresponding parts of the tick. The ornamental colour-producing layer can be scraped away from the underside of the scutum in most ornate ticks and it is removable from such ticks by the use of caustic potash.The whitish or creamy coloration that is so characteristic of most species of Dermacentor and the three ornate species of Rhipicephalus that are known to science, appears on the other hand to depend largely upon inclusions or structural changes within the chitin itself, whence the persistence of the creaminess seen by reflected light in the caustic-treated ticks. Similar, but less distinct, appearances may be seen in ticks belonging to other genera. Dermacentor rhinocerotis, which does not exhibit creamy coloration but only dull yellowish spots when dry, is totally decolorized by caustic potash, whilst contrary to most species of its genus it shows metallic coloration in well-preserved specimens in alcohol.The examination of caustic-treated specimens was carried out upon 31 species of ornate ticks, i.e. Dermacentor (8), Rhipicephalus (3), Amblyomma (15), Aponomma (4) and Hyalomma (1 species).The coloration and creamy ornamentation, herein distinguished, appear to be confined to the thinner portions of the exoskeleton. That the characteristic dark markings correspond to thicker and more darkly chitinised portions of the scutum is demonstrable by dissections, caustic-treated, or sectioned specimens; this being especially evident for instance in Amblyomma. The orange spot on the scutum of A. splendidum offers an exception.The optical and chemical study of coloration in ticks deserves further investigation.


2018 ◽  
Vol 90 (11) ◽  
pp. 1685-1701 ◽  
Author(s):  
Elena V. Golubina ◽  
Tatiana N. Rostovshchikova ◽  
Ekaterina S. Lokteva ◽  
Konstantin I. Maslakov ◽  
Sergey A. Nikolaev ◽  
...  

Abstract NiPd bimetallic systems were for the first time synthesized by laser electrodispersion (LED) of the Ni77Pd23 alloy target followed by the deposition of produced bimetallic particles on a TEM copper grid and alumina granules. Selective area energy-dispersive analysis confirms the bimetallic nature of NiPd particles deposited on a TEM copper grid. Their mean size is 1.0 nm according to TEM. XPS data demonstrate that under deposition on alumina granules (total metal content of 0.005 wt.%), nickel in bimetallic particles nearly completely oxidizes to Ni2+ species predominantly in the form of aluminate. At the same time major part of palladium (84%) exists in Pd0 but oxidizes to Pd2+ (80%) during 6 months storage in air. Both metals are deposited on the external surface of alumina granules and localized in the same areas. In situ reduction of both metals by H2 in the catalytic cell of XPS spectrometer is hindered. Nickel is not reduced even at 450°C, confirming the formation of NiAlOx, whereas palladium is reduced at higher temperatures compared to a similar monometallic catalyst. Nevertheless, NiPd/Al2O3 catalyst is more efficient in gas-phase chlorobenzene hydrodechlorination at 150–350°C than Ni/Al2O3 and even Pd/Al2O3, and much more stable. The difference may be caused by the formation of new active sites due to the contact between Pd0 and NiAlOx-modified support, and the protective action of spinel reacting with HCl by-product.


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