scholarly journals Benzoyl Peroxide Oxidation Route to the Synthesis of Solvent Soluble Polycarbazole

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Rajender Boddula ◽  
Palaniappan Srinivasan
Keyword(s):  
Thermal Stability ◽  
Emulsion Polymerization ◽  
Benzoyl Peroxide ◽  
Room Temperature ◽  
The Other ◽  
Solution Polymerization ◽  
Peroxide Oxidation ◽  
Polar Solvents ◽  
Amorphous Nature ◽  
First Time

Carbazole was oxidized by benzoyl peroxide in presence of p-toluenesulfonic acid to polycarbazole salt at room temperature for the first time. Polycarbazole salts were synthesized via solution and emulsion polymerization pathways. Polycarbazole bases were prepared by dedoping from polycarbazole salts. Formation of polycarbazoles was confirmed from infrared, electronic absorption and EDAX spectra. Polycarbazole salt was obtained in amorphous nature in semiconductor range (10−5 S/cm), which was found to be soluble in less and high polar solvents. Polycarbazole salt prepared by emulsion polymerization pathway showed mixture of shapes with microrod, sphere, and pores, whereas its corresponding base showed only micropores structure. On the other hand, polycarbazole salt and its corresponding base prepared by solution polymerization pathway showed flake-like morphology. Higher thermal stability was obtained for polycarbazole salt prepared by emulsion polymerization pathway than that of the salt prepared by solution polymerization pathway.

Dependence of Vickers Hardness on Annealing Temperature at Co/Cu Multilayered Films

2007 ◽  
Vol 561-565 ◽  
pp. 2399-2402
Author(s):  
Yoshihisa Kaneko ◽  
H. Sakakibara ◽  
Satoshi Hashimoto
Keyword(s):  
Thermal Stability ◽  
Vickers Hardness ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Copper Substrate ◽  
The Other ◽  
Multilayered Structures ◽  
Multilayered Films ◽  
Hardness Tests ◽  
Thermal Stability Of

Co/Cu and Ni/Cu multilayers fabricated by electroplating technique were annealed at various temperatures in order to investigate thermal stability of multilayered structures. Vickers hardness tests on the annealed Co/Cu and Ni/Cu multilayers were conducted at room temperature. It was recognized that after the annealing at 1023K the Co/Cu multilayer still maintained the hardness of as-deposited state. On the other hand, the hardness of Ni/Cu multilayer was almost identical to copper substrate after the annealing at 903K.

scholarly journals Synthesis of PMMA-HoVO4 nanocomposites by emulsifier-free emulsion polymerization: radical effects

2020 ◽  
Vol 38 (1) ◽  
pp. 143-150
Author(s):  
B. Bulbul ◽  
E.Y. Pekcaliskan ◽  
S. Beyaz
Keyword(s):  
Emulsion Polymerization ◽  
Room Temperature ◽  
The Other ◽  
Nanoparticle Dispersion ◽  
Emulsion System ◽  
Polymer Beads ◽  
Polymerization System ◽  
Infrared Spectral ◽  
New Material

AbstractPoly(methyl methacrylate)-holmium orthovanadate (PMMA-HoVO4) nanocomposites were synthesized using emulsifierfree emulsion polymerization system in two ways. In the first one, the HoVO4 nanoparticle dispersion was added to the emulsion system before or after polymerization start (in situ polymerization). In the other one, nanoparticle dispersion and polymeric latex were mixed together at room temperature (blending). Crystalline HoVO4 nanoparticles (about 60 nm) were synthesized by coprecipitation method. Three different composite latexes were synthesized by varying the potassium persulfate concentration and the time of HoVO4 nanoparticles addition. According to the dynamic light scattering analysis, the size of the polymer beads in the latexes is between 244.8 nm and 502.5 nm and the PDI values are in the range of 0.005 to 0.206. Infrared spectral analysis showed that HoVO4 caused some changes in the structure of the polymer. Luminescence measurements attempted to determine optical properties of the nanocomposites. The results have shown that HoVO4 nanoparticles do not protect their structure due to the reaction with persulfate radicals but that they enter the polymer beads and change the luminescence properties of the polymer forming a new material with different properties.

Microstructure and Thermal Stability in CP Titanium Processed by Electroplastic Rolling

2011 ◽  
Vol 465 ◽  
pp. 215-218 ◽  
Author(s):  
Jenő Gubicza ◽  
E. Khosravi ◽  
Vladimir V. Stolyarov
Keyword(s):  
Thermal Stability ◽  
Formation Energy ◽  
Room Temperature ◽  
The Other ◽  
Burgers Vector ◽  
Relative Fraction ◽  
Electroplastic Rolling ◽  
Ultrafine Grained ◽  
Titanium Grade ◽  
A Current

Ultrafine-grained (UFG) CP titanium (Grade-4) sample was processed by electroplastic rolling (EPR) at room temperature which was compared to a specimen processed by conventional cold rolling (CR). EPR was performed using pulsed unidirectional current with a current density of 95 A/mm2, pulse duration of 10-4 s and frequency of 1000 Hz. It was found that the sample processed by EPR has slightly higher dislocation density and smaller crystallite size than for the CR specimen resulting in a higher tensile strength for the former specimen. In the case of EPR sample, the relative fraction of <c+a> dislocations is lower than for CR specimen. During annealing the relative fraction of <c+a> dislocations decreased for both samples which can be explained by the fact that the <c+a> dislocations have larger Burgers-vector and consequently higher formation energy than the other two types.

scholarly journals Lattice Sites and Stability of Implanted Er in FZ and CZ Si

1997 ◽  
Vol 486 ◽  
Author(s):  
U. Wahl ◽  
J. G. Correia ◽  
G. Langouche ◽  
A. Vantomme ◽  
Isolde collaboration
Keyword(s):  
Thermal Stability ◽  
Electron Emission ◽  
Room Temperature ◽  
The Other ◽  
Implantation Damage ◽  
Prolonged Annealing ◽  
High Fraction ◽  
Higher Doses ◽  
Low Symmetry ◽  
Emission Channeling

AbstractWe report on the lattice location of 167Er in Si measured by conversion electron emission channeling. In both FZ and CZ Si, a high fraction of Er (>65%) occupies near-tetrahedral interstitial (T) sites directly following 60 keV room temperature implantation at doses of 6× 1012 cm−2 For higher doses, the as-implanted near-T fractions of Er visible by emission channeling are smaller, due to the beginning of amorphization. Following the recovery of implantation damage at 600°C, more than 70% of Er is found on near-T sites in both FZ and CZ Si. In FZ Si, Er exhibits a remarkable thermal stability and only prolonged annealing for several hours reduces the near-T fraction. On the other hand, annealing of CZ Si at 900°C for more than 10 minutes results in the majority of Er probes in sites of very low symmetry or disordered surroundings.

scholarly journals Onset of planet formation in the warm inner disk

2019 ◽  
Vol 629 ◽  
pp. A66 ◽  
Author(s):  
Tunahan Demirci ◽  
Corinna Krause ◽  
Jens Teiser ◽  
Gerhard Wurm
Keyword(s):  
Size Distribution ◽  
Room Temperature ◽  
Filling Factor ◽  
Planet Formation ◽  
Protoplanetary Disks ◽  
The Other ◽  
Sticking Probability ◽  
Wide Range ◽  
First Time ◽  
Wide Size Distribution

Aims. Collisional growth of dust occurs in all regions of protoplanetary disks with certain materials dominating between various condensation lines. The sticking properties of the prevalent dust species depend on the specific temperatures. The inner disk is the realm of silicates spanning a wide range of temperatures from room temperature up to sublimation beyond 1500 K. Methods. For the first time, we carried out laboratory collision experiments with hot levitated basalt dust aggregates of 1 mm in size. The aggregates are compact with a filling factor of 0.37 ± 0.06. The constituent grains have a wide size distribution that peaks at about 0.6 μm. Temperatures in the experiments are varied between approximately 600 and 1100 K. Results. Collisions are slow with velocities between 0.002 and 0.15 m s−1, i.e., relevant for protoplanetary disks. Aside from variations of the coefficients of restitution due to varying collision velocities, the experiments show low sticking probability below 900 K and an increasing sticking probability starting at 900 K. Conclusions. This implies that dust can grow to larger size in hot regions, which might change planet formation. One scenario is an enhanced probability for local planetesimal formation. Another scenario is a reduction of planetesimal formation as larger grains are more readily removed as a consequence of radial drift. However, the increased growth at high temperatures likely changes planetesimal formation one way or the other.

Electron microscope studies of the plastic deformation of ternary alloys based on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 1120-1120
Author(s):  
R. Haswell ◽  
U. Bangert ◽  
P. Charsley
Keyword(s):  
Plastic Deformation ◽  
Electron Microscope ◽  
Room Temperature ◽  
Stacking Faults ◽  
The Other ◽  
Ternary Alloys ◽  
Dislocation Mobility ◽  
Semiconducting Materials ◽  
Micro Indentation

A knowledge of the behaviour of dislocations in semiconducting materials is essential to the understanding of devices which use them . This work is concerned with dislocations in alloys related to the semiconductor GaAs . Previous work on GaAs has shown that microtwinning occurs on one of the <110> rosette arms after indentation in preference to the other . We have shown that the effect of replacing some of the Ga atoms by Al results in microtwinning in both of the rosette arms.In the work to be reported dislocations in specimens of different compositions of Gax Al(1-x) As and Gax In(1-x) As have been studied by using micro indentation on a (001) face at room temperature . A range of electron microscope techniques have been used to investigate the type of dislocations and stacking faults/microtwins in the rosette arms , which are parallel to the [110] and [10] , as a function of composition for both alloys . Under certain conditions microtwinning occurs in both directions . This will be discussed in terms of the dislocation mobility.

Darwin's two competing phylogenetic trees: marsupials as ancestors or sister taxa?

2012 ◽  
Vol 39 (2) ◽  
pp. 217-233 ◽  
Author(s):  
J. David Archibald
Keyword(s):  
Fossil Record ◽  
Evolutionary Biology ◽  
Phylogenetic Trees ◽  
Charles Darwin ◽  
The Other ◽  
Charles Lyell ◽  
Single Origin ◽  
Molecular Studies ◽  
Richard Owen ◽  
First Time

Studies of the origin and diversification of major groups of plants and animals are contentious topics in current evolutionary biology. This includes the study of the timing and relationships of the two major clades of extant mammals – marsupials and placentals. Molecular studies concerned with marsupial and placental origin and diversification can be at odds with the fossil record. Such studies are, however, not a recent phenomenon. Over 150 years ago Charles Darwin weighed two alternative views on the origin of marsupials and placentals. Less than a year after the publication of On the origin of species, Darwin outlined these in a letter to Charles Lyell dated 23 September 1860. The letter concluded with two competing phylogenetic diagrams. One showed marsupials as ancestral to both living marsupials and placentals, whereas the other showed a non-marsupial, non-placental as being ancestral to both living marsupials and placentals. These two diagrams are published here for the first time. These are the only such competing phylogenetic diagrams that Darwin is known to have produced. In addition to examining the question of mammalian origins in this letter and in other manuscript notes discussed here, Darwin confronted the broader issue as to whether major groups of animals had a single origin (monophyly) or were the result of “continuous creation” as advocated for some groups by Richard Owen. Charles Lyell had held similar views to those of Owen, but it is clear from correspondence with Darwin that he was beginning to accept the idea of monophyly of major groups.

Sphagnum mosses (Sphagnaceae, Bryophyta) of mires Chefandzar and Masota in North Ossetia (Caucasus)

2018 ◽  
Vol 52 (2) ◽  
pp. 455-462 ◽  
Author(s):  
G. Ya. Doroshina ◽  
I. A. Nikolajev
Keyword(s):  
Plant Communities ◽  
The Other ◽  
North Caucasus ◽  
Sphagnum Mosses ◽  
Greater Caucasus ◽  
The North ◽  
First Time ◽  
North Ossetia

Sphagnum mires on the Greater Caucasus are rare, characterized by the presence of relict plant communities of glacial age and are in a stage of degradation. The study of Sphagnum of Chefandzar and Masota mires is carried out for the first time. Seven species of Sphagnum are recorded. Their distribution and frequency within the North Caucasus are analyzed. Sphagnum contortum, S. platyphyllum, S. russowii, S. squarrosum are recorded for the first time for the study area and for the flora of North Ossetia. The other mosses found in the study area are listed.

An Epistemological Criticism of Social Entrepreneurship: Is Social Entrepreneurship a Sound Scientific Field of Research

2018 ◽  
Author(s):  
Amir Forouharfar
Keyword(s):  
Social Entrepreneurship ◽  
Social Constructivism ◽  
Social Epistemology ◽  
American English ◽  
Meta Analysis ◽  
Research Question ◽  
Knowledge Structure ◽  
Scientific Field ◽  
The Other ◽  
First Time

The paper was shaped around the pivotal question: Is SE a sound and scientific field of research? The question has given a critical tone to the paper and has also helped to bring out some of the controversial debates in the realm of SE. The paper was organized under five main discussions to be able to provide a scientific answer to the research question: (1)<b> </b>is “social entrepreneurship” an oxymoron?, (2) the characteristics of SE knowledge, (3) sources of social entrepreneurship knowledge, (4) SE knowledge: structure and limitations and (5) contributing epistemology-making concepts for SE.<b> </b>Based on the sections,<b> </b>the study relied on the relevant philosophical schools of thought in <i>Epistemology </i>(e.g. <i>Empiricism</i>, <i>Rationalism</i>, <i>Skepticism</i>, <i>Internalism</i> vs. <i>Externalism</i>,<i> Essentialism, Social Constructivism</i>, <i>Social Epistemology, etc.</i>) to discuss these controversies around SE and proposes some solutions by reviewing SE literature. Also, to determine the governing linguistic discourse in the realm of SE, which was necessary for our discussion,<i> Corpus of Contemporary American English (COCA)</i> for the first time in SE studies was used. Further, through the study, SE buzzwords which constitute SE terminology were derived and introduced to help us narrowing down and converging the thoughts in this field and demarking the epistemological boundaries of SE. The originality of the paper on one hand lies in its pioneering discussions on SE epistemology and on the other hand in paving the way for a construction of sound epistemology for SE; therefore in many cases after preparing the philosophical ground for the discussions, it went beyond the prevalent SE literature through meta-analysis to discuss the cases which were raised. The results of the study verified previously claimed embryonic pre-paradigmatic phase in SE which was far from a sound and scientific knowledge, although the scholarly endeavors are the harbingers of such a possibility in the future which calls for further mature academic discussion and development of SE knowledge by the SE academia.

A Nabatean port on the Red Sea: note on the pottery finds from al-Qusayr (al-Wajh, Saudi Arabia)

2020 ◽  
Author(s):  
Caroline Durand
Keyword(s):  
Saudi Arabia ◽  
19Th Century ◽  
Red Sea ◽  
Point Of View ◽  
The Other ◽  
Trade Routes ◽  
Other Hand ◽  
Roman Egypt ◽  
Pottery Sherds ◽  
First Time

Al-Qusayr is located 40 km south of modern al-Wajh, roughly 7 km from the eastern Red Sea shore. This site is known since the mid-19th century, when the explorer R. Burton described it for the first time, in particular the remains of a monumental building so-called al-Qasr. In March 2016, a new survey of the site was undertaken by the al-‘Ula–al-Wajh Survey Project. This survey focused not only on al-Qasr but also on the surrounding site corresponding to the ancient settlement. A surface collection of pottery sherds revealed a striking combination of Mediterranean and Egyptian imports on one hand, and of Nabataean productions on the other hand. This material is particularly homogeneous on the chronological point of view, suggesting a rather limited occupation period for the site. Attesting contacts between Mediterranean merchants, Roman Egypt and the Nabataean kingdom, these new data allow a complete reassessment of the importance of this locality in the Red Sea trade routes during antiquity.

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