On the role of vacancies in the process of self-diffusion at low temperatures

2002 ◽  
Vol 28 (5) ◽  
pp. 430-433 ◽  
Author(s):  
M. N. Magomedov
Keyword(s):  
Low Temperatures ◽  
Self Diffusion

scholarly journals Helium-3 gas self-diffusion in a nematically ordered aerogel at low temperatures: enhanced role of adsorption

2017 ◽  
Vol 19 (34) ◽  
pp. 23146-23153
Author(s):  
Vyacheslav Kuzmin ◽  
Kajum Safiullin ◽  
Andrey Stanislavovas ◽  
Murat Tagirov
Keyword(s):  
Low Temperatures ◽  
Gas Diffusion ◽  
Self Diffusion ◽  
Adsorption Effects ◽  
Helium 3

The unpredictably enhanced role of adsorption effects on gas diffusion in an oriented aerogel is demonstrated.

The Role of the Initiator System in the Synthesis of Acidic Multifunctional Nanoparticles Designed for Molecular Imprinting of Proteins

2020 ◽  
Vol 65 (1) ◽  
pp. 28-41
Author(s):  
Marwa Aly Ahmed ◽  
Júlia Erdőssy ◽  
Viola Horváth
Keyword(s):  
Acrylic Acid ◽  
Binding Affinity ◽  
Molecular Imprinting ◽  
Low Temperatures ◽  
Ammonium Persulfate ◽  
Sodium Bisulfite ◽  
Multifunctional Nanoparticles ◽  
High Affinity ◽  
Initiator System

Multifunctional nanoparticles have been shown earlier to bind certain proteins with high affinity and the binding affinity could be enhanced by molecular imprinting of the target protein. In this work different initiator systems were used and compared during the synthesis of poly (N-isopropylacrylamide-co-acrylic acid-co-N-tert-butylacrylamide) nanoparticles with respect to their future applicability in molecular imprinting of lysozyme. The decomposition of ammonium persulfate initiator was initiated either thermally at 60 °C or by using redox activators, namely tetramethylethylenediamine or sodium bisulfite at low temperatures. Morphology differences in the resulting nanoparticles have been revealed using scanning electron microscopy and dynamic light scattering. During polymerization the conversion of each monomer was followed in time. Striking differences were demonstrated in the incorporation rate of acrylic acid between the tetramethylethylenediamine catalyzed initiation and the other systems. This led to a completely different nanoparticle microstructure the consequence of which was the distinctly lower lysozyme binding affinity. On the contrary, the use of sodium bisulfite activation resulted in similar nanoparticle structural homogeneity and protein binding affinity as the thermal initiation.

Diffusion Mechanisms in Sige Alloys

1999 ◽  
Vol 568 ◽  
Author(s):  
Arthur F.W. Willoughby ◽  
Janet M. Bonar ◽  
Andrew D.N. Paine
Keyword(s):  
Diffusion Processes ◽  
Dopant Diffusion ◽  
Elemental Silicon ◽  
Self Diffusion ◽  
Si Substrates ◽  
Marker Layer ◽  
Diffusion Mechanisms ◽  
Silicon And Germanium ◽  
Charged Defects

ABSTRACTInterest in diffusion processes in SiGe alloys arises from their potential in HBT's, HFET's, and optoelectronics devices, where migration over distances as small as a few nanometres can be significant. Successful modelling of these processes requires a much improved understanding of the mechanisms of self- and dopant diffusion in the alloy, although recent progress has been made. It is the purpose of this review to set this in the context of diffusion processes in elemental silicon and germanium, and to identify how this can help to elucidate behaviour in the alloy. Firstly, self diffusion processes are reviewed, from general agreement that self-diffusion in germanium is dominated by neutral and acceptor vacancies, to the position in silicon which is still uncertain. Germanium diffusion in silicon, however, appears to be via both vacancy and interstitial processes, and in the bulk alloy there is evidence for a change in dominant mechanism at around 35 percent germanium. Next, a review of dopant diffusion begins with Sb, which appears to diffuse in germanium by a mechanism similar to self-diffusion, and in silicon via monovacancies also, from marker layer evidence. In SiGe, the effects of composition and strain in epitaxial layers on Si substrates are also consistent with diffusion via vacancies, but questions still remain on the role of charged defects. The use of Sb to monitor vacancy effects such as grown-in defects by low temperature MBE, are discussed. Lastly, progress in assessing the role of vacancies and interstitials in the diffusion of boron is reviewed, which is dominated by interstitials in silicon-rich alloys, but appears to change to domination by vacancies at around 40 percent germanium, although studies in pure germanium are greatly needed.

The role of Pt in α-MoC on the water-gas shift reaction at low temperatures

Joule ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 521-523
Author(s):  
Tiago J. Goncalves ◽  
Samira Siahrostami
Keyword(s):  
Low Temperatures ◽  
Water Gas Shift ◽  
Water Gas Shift Reaction ◽  
Shift Reaction ◽  
Water Gas

Some Considerations on Confined Water: The Thermal Behavior of Transport Properties in Water-Glycerol and Water-Methanol Mixtures

MRS Advances ◽  
2016 ◽  
Vol 1 (26) ◽  
pp. 1891-1902 ◽  
Author(s):  
Francesco Mallamace ◽  
Carmelo Corsaro ◽  
Domenico Mallamace ◽  
Cirino Vasi ◽  
Sebastiano Vasi ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Molar Fraction ◽  
Relaxation Times ◽  
Confined Water ◽  
Self Diffusion ◽  
Excess Value ◽  
Water Glycerol ◽  
System Properties ◽  
Dynamical Crossover

ABSTRACTWe discuss recent literature data on the relaxation times (the primary tα), viscosity, and self-diffusion in water-glycerol and water-methanol mixtures across a wide temperature range from the stable water phase to the deep supercooled regime (373–147K). In particular, to clarify the role of hydrophilicity interactions (the hydrogen bonds) and hydrophobic interactions we study the mixture in terms of the water molar fraction (XW) with fixed temperatures at 5K steps across the entire composition range, and we find a marked deviation from the ideal thermodynamic behavior of the transport functions. This deviation is strongly T and XW dependent and spans values that range from two orders of magnitude at the highest temperature to more than five in the deeply supercooled regime (more precisely, at ≃200K). We analyze these deviations in terms of how the measured values differ from ideal values and find that the hydrogen-bonding water network dominates system properties up to XW = 0.3. We also examine an Arrhenius plot of the maximum excess value (Δtα(T) vs. 1/T) and find two significant changes due to water: one at the dynamical crossover temperature (TL ≃ 225K, i.e., the locus of the Widom line), and one at T ≃ 315K (the water isothermal compressibility χT minimum).

Self-diffusion in copper at low temperatures

1974 ◽  
Vol 23 (1) ◽  
pp. K35-K38 ◽  
Author(s):  
Nghi Q. Lam ◽  
S. J. Rothman ◽  
L. J. Nowicki
Keyword(s):  
Low Temperatures ◽  
Self Diffusion

scholarly journals ACCUMULATION BEHAVIOUR OF ALLANTOIN IN THE UNDERGROUND PHYTOMASS OF THE BORAGINACEAE FAMILY AND ITS ROLE IN ADAPTING THE PLANTS TO ADVERSE ENVIRONMENTAL FACTORS

2019 ◽  
Vol 14 (1) ◽  
pp. 126-136
Author(s):  
A. Ya. Tamakhina ◽  
A. A. Akhkubekova ◽  
A. B. Ittiev
Keyword(s):  
Solar Radiation ◽  
Sea Level ◽  
Low Temperatures ◽  
High Performance ◽  
Growing Season ◽  
Stress Factors ◽  
Adaptation To Stress ◽  
Plant Adaptation ◽  
The Family

Aim.The aim of the work described herein was to study the dynamics of allantoin accumulation in the underground phytomass ofEchium vulgareL.,Symphytum caucasicumM. Bieb. andS. asperumLepech. as well as to clarify the role of allantoin in plant adaptation to stress factors.Methods.We studied the roots of plants growing in the foothill (Nalchik, 490–512 m above sea level) and the mountain zones of the Kabardino-Balkarian Republic (Terskol village, 2530 m above sea level; Verkhnyaya Balkaria village, 2680 m above sea level). The roots were collected at the stages of rosetting, flowering, fruiting and at the end of the growing season. Aqueous-alcoholic extracts of shredded roots were analyzed by high-performance liquid chromatography.Results.The highest content of allantoin in the roots ofEchium vulgare,Symphytum caucasicum,S. asperumplants was noted at the end of the growing season, respectively 0.915; 0.342–0.658; 2,842–3,426%. Under conditions of low temperatures and increased solar radiation, the content of allantoin in the roots increases 1.2–1.9 times as compared with the plants of the foothill zone.Conclusion.Allantoin plays an important role in the process of adapting species of the family Boraginaceae to oxidative stress caused by hypothermia and increased solar radiation.

Effect of temperature on transition and transversion mutagenesis: characterization of wild type and a mutator T4 DNA polymerase mutant

1984 ◽  
Vol 26 (3) ◽  
pp. 386-389 ◽  
Author(s):  
Linda J. Reha-Krantz ◽  
Sükran Parmaksizoglu
Keyword(s):  
Dna Polymerase ◽  
Low Temperatures ◽  
Bacteriophage T4 ◽  
Effect Of Temperature ◽  
In Vitro Mutagenesis ◽  
Wild Type ◽  
Mutational Site

The effect of temperature on genetically well-defined mutational pathways was examined in the bacteriophage T4. The mutational site was a T4 rII ochre mutant which could revert to rII+ via a transversion or to the amber convertant via a transition. Temperature did not strongly affect any of the pathways examined in a wild-type background; however, increased temperature reduced the mutational activity of a mutator DNA polymerase mutant. Possible models to explain the role of temperature in mutagenesis are discussed as well as the significance of low temperatures for in vitro mutagenesis reactions.Key words: bacteriophage T4, mutator, transition, transversion, temperature effects.

Self Diffusion in SiC: the Role of Intrinsic Point Defects

2001 ◽  
Vol 353-356 ◽  
pp. 323-326 ◽  
Author(s):  
Alexander Mattausch ◽  
M. Bockstedte ◽  
Oleg Pankratov
Keyword(s):  
Point Defects ◽  
Intrinsic Point Defects ◽  
Self Diffusion
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