scholarly journals CONSTITUENT TRANSPORT IN ESTUARIES

1968 ◽  
Vol 1 (11) ◽  
pp. 86 ◽  
Author(s):  
Bard Glenne
Keyword(s):  
Diffusion Process ◽  
Diffusion Coefficients ◽  
Considerable Progress ◽  
Diffusion Method ◽  
Common Application ◽  
Made In ◽  
Mixing And Transport

During the last two decades considerable progress has been made in analyzing the diffusion process in estuaries. Unfortunately, certain difficulties (e g prediction of diffusion coefficients) still prevent common application of the diffusion method An old technique, related to the diffusion concept, can however, frequently give useful information regarding constituent mixing and transport velocities in natural estuaries.

Diffusion in Very Dilute Zr-Fe Alloys

2009 ◽  
Vol 283-286 ◽  
pp. 128-132
Author(s):  
Rodolfo A. Pérez
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Process ◽  
Ab Initio Calculations ◽  
Diffusion Coefficients ◽  
Fast Diffusion ◽  
Self Diffusion ◽  
Diffusion Enhancement ◽  
Fe Alloys ◽  
Theoretical Results ◽  
Made In

The diffusion process in hcp Zr with low amounts of Fe being in solution or forming very dilute Zr-Fe alloys is analysed and discussed. The enhancement of the diffusion coefficient in alloys with increasing amounts of Fe is studied using both experimental and theoretical results. In contraposition with the assumption made in the literature that the Fe in solution in the hcp Zr lattice is the responsible, this enhancement seems to be more related with the total amount of Fe present in the samples. This idea is supported by measurements of Au diffusion in Zr with 50 to 150 gr/gr of Fe which shows increments in the diffusion coefficients even at the lower temperatures where the reported Fe solubility in -Zr is negligible. Ab initio calculations using SIESTA and WIEN2k codes show several stable and meta-stable configurations for the Fe in the hcp Zr lattice in interstitial and off-centre positions, resembling the last ones a Zr3Fe like arrangement. These configurations are used in order to analyze the mechanism of both, self-diffusion enhancement and ultra-fast diffusion of Fe in -Zr.

Biological Production of (S)-acetoin: A State-of-the-Art Review

2019 ◽  
Vol 19 (25) ◽  
pp. 2348-2356 ◽  
Author(s):  
Neng-Zhong Xie ◽  
Jian-Xiu Li ◽  
Ri-Bo Huang
Keyword(s):  
Side Effects ◽  
Chemical Synthesis ◽  
State Of The Art ◽  
Optically Active ◽  
Considerable Progress ◽  
Future Prospects ◽  
Chiral Compound ◽  
Biological Production ◽  
Acetoin Production ◽  
Made In

Acetoin is an important four-carbon compound that has many applications in foods, chemical synthesis, cosmetics, cigarettes, soaps, and detergents. Its stereoisomer (S)-acetoin, a high-value chiral compound, can also be used to synthesize optically active drugs, which could enhance targeting properties and reduce side effects. Recently, considerable progress has been made in the development of biotechnological routes for (S)-acetoin production. In this review, various strategies for biological (S)- acetoin production are summarized, and their constraints and possible solutions are described. Furthermore, future prospects of biological production of (S)-acetoin are discussed.

scholarly journals Theoretical Modelling of Ion Exchange Processes in Glass: Advances and Challenges

2021 ◽  
Vol 11 (11) ◽  
pp. 5070
Author(s):  
Xesús Prieto-Blanco ◽  
Carlos Montero-Orille
Keyword(s):  
Ion Exchange ◽  
Diffusion Coefficients ◽  
Molten Salts ◽  
Theoretical Modelling ◽  
Copper Films ◽  
Theoretical Frameworks ◽  
Self Diffusion ◽  
Exchange Processes ◽  
The One ◽  
Made In

In the last few years, some advances have been made in the theoretical modelling of ion exchange processes in glass. On the one hand, the equations that describe the evolution of the cation concentration were rewritten in a more rigorous manner. This was made into two theoretical frameworks. In the first one, the self-diffusion coefficients were assumed to be constant, whereas, in the second one, a more realistic cation behaviour was considered by taking into account the so-called mixed ion effect. Along with these equations, the boundary conditions for the usual ion exchange processes from molten salts, silver and copper films and metallic cathodes were accordingly established. On the other hand, the modelling of some ion exchange processes that have attracted a great deal of attention in recent years, including glass poling, electro-diffusion of multivalent metals and the formation/dissolution of silver nanoparticles, has been addressed. In such processes, the usual approximations that are made in ion exchange modelling are not always valid. An overview of the progress made and the remaining challenges in the modelling of these unique processes is provided at the end of this review.

scholarly journals III. On the nature and construction of the sun and fixed stars

1795 ◽  
Vol 85 ◽  
pp. 46-72 ◽  
Keyword(s):  
Central Body ◽  
Planetary System ◽  
Considerable Progress ◽  
The Sun ◽  
Great Satisfaction ◽  
The Earth ◽  
The World ◽  
Celestial Bodies ◽  
The Universe ◽  
Made In

Among the celestial bodies the sun is certainly the first which should attract our notice. It is a fountain of light that illuminates the world! it is the cause of that heat which main­tains the productive power of nature, and makes the earth a fit habitation for man! it is the central body of the planetary system; and what renders a knowledge of its nature still more interesting to us is, that the numberless stars which compose the universe, appear, by the strictest analogy, to be similar bodies. Their innate light is so intense, that it reaches the eye of the observer from the remotest regions of space, and forcibly claims his notice. Now, if we are convinced that an inquiry into the nature and properties of the sun is highly worthy of our notice, we may also with great satisfaction reflect on the considerable progress that has already been made in our knowledge of this eminent body. It would require a long detail to enumerate all the various discoveries which have been made on this subject; I shall, therefore, content myself with giving only the most capital of them.

Depressive Illnesses in Children and Adolescents: A Review of Current Concepts

1985 ◽  
Vol 30 (2) ◽  
pp. 119-129 ◽  
Author(s):  
B.J. Mcconville ◽  
R.T. Bruce
Keyword(s):  
Children And Adolescents ◽  
Current Knowledge ◽  
Considerable Progress ◽  
Childhood And Adolescence ◽  
Age Related ◽  
Developmental Age ◽  
The Subject ◽  
Made In

Considerable progress has been made in our understanding of depressive illnesses in childhood and adolescence, especially over the last several years. A number of major books on the subject have now appeared, along with a large number of individual papers. This paper attempts to summarize current knowledge, and indicates developmental, age-related and other issues which still require further study.

Cosmic y-ray bursts

1981 ◽  
Vol 301 (1462) ◽  
pp. 645-658 ◽  
Keyword(s):  
Temporal Structure ◽  
Considerable Progress ◽  
Large Network ◽  
Exact Location ◽  
Made In ◽  
Arrival Directions

Although y-ray bursts were discovered over ten years ago, the study of their temporal structure, their spectrum and their lg N against lg S distribution have still not enabled scientists to determine their origin. Since 1978, however, considerable progress has been made in the accuracy of locating bursts by triangulation methods, by using a large network of observations made by the Helios B solar-orbiting satellite, the interplanetary spacecraft Pioneer Venus and Venera 11 and 12, ISEE-C and Earth-orbiting satellites. With the great distances between these various measuring points, it can be hoped that an accuracy of the order of one minute of arc will be attained for many events observed in 1979 and 1980. This accuracy has already been surpassed for the March 5, 1979 event. In this paper an analysis of the latest observations, and results on the exact location of the arrival directions of several bursts will be presented, along with the evidence they provide about the origin of this radiation.

Applying lessons learnt from deficiencies in the basel accords to Solvency II

2013 ◽  
Vol 6 (2) ◽  
pp. 309-328
Author(s):  
Johann Jacobs ◽  
Gary Van Vuuren
Keyword(s):  
European Union ◽  
Financial Crisis ◽  
Banking Sector ◽  
Insurance Industry ◽  
Solvency Ii ◽  
Capital Adequacy ◽  
Considerable Progress ◽  
Eu Legislation ◽  
Basel Accords ◽  
Made In

Solvency II is the new European Union (EU) legislation that will review the capital adequacy regime for the insurance industry. Considerable progress has been made in the banking sector with the implementation of the Basel Accords (Basel). The implementation of Solvency II, therefore, brings with it an opportunity for the insurance industry to assess the successes, weaknesses and shortcomings experienced by the banking sector's implementation of Basel so as to learn from them and ensure that Solvency II's implementation duplicates the successes and avoids the failures of Basel's. This article critically explores weaknesses and failures of Basel which were exacerbated and/or exploited by the financial crisis of 2007-2010 and provides advice on how these might be mitigated or avoided in the implementation of Solvency II.

scholarly journals Vitiligo: A Review

Dermatology ◽  
2020 ◽  
Vol 236 (6) ◽  
pp. 571-592 ◽  
Author(s):  
Christina Bergqvist ◽  
Khaled Ezzedine
Keyword(s):  
Autoimmune Disease ◽  
Skin Disorder ◽  
Current Knowledge ◽  
Daily Life ◽  
Considerable Progress ◽  
International Consensus ◽  
Selective Loss ◽  
The Future ◽  
Cosmetic Problem ◽  
Made In

Vitiligo, a common depigmenting skin disorder, has an estimated prevalence of 0.5–2% of the population worldwide. The disease is characterized by the selective loss of melanocytes which results in typical nonscaly, chalky-white macules. In recent years, considerable progress has been made in our understanding of the pathogenesis of vitiligo which is now clearly classified as an autoimmune disease. Vitiligo is often dismissed as a cosmetic problem, although its effects can be psychologically devastating, often with a considerable burden on daily life. In 2011, an international consensus classified segmental vitiligo separately from all other forms of vitiligo, and the term vitiligo was defined to designate all forms of nonsegmental vitiligo. This review summarizes the current knowledge on vitiligo and attempts to give an overview of the future in vitiligo treatment.

Preparation of Y-BA-CU Oxide Superconducting Composite Tapes by a Diffusion Process

1987 ◽  
Vol 99 ◽  
Author(s):  
K. Tachikawa ◽  
M. Sugimoto ◽  
N. Sadakata ◽  
O. Kohno
Keyword(s):  
Diffusion Process ◽  
Critical Current ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Oxide Compound ◽  
High Tc ◽  
Powder Metallurgical Process ◽  
Current Densities ◽  
Wire Fabrication ◽  
Made In

Since discovery of the Y-Ba-Cu oxide compound showing superconductivity above liquid nitrogen temperature, intensive study has been under way to clarify nature of the high Tc oxides[l-4]. Much efforts were also made in the field of superconductor applications. A number of studies have been carried out by a powder metallurgical process of Y-Ba-Cu oxide compound wires, although, obtained critical current densities were still low at liquid nitrogen temperature[5–6]. Other techniques for wire fabrication is also being attempted[7–9]. In this study, Y-Ba-Cu oxide superconducting composite tapes were prepared by a diffusion process, which is one of the promising methods to obtain a high critical current density.

scholarly journals Titans of the early Universe: The Prato statement on the origin of the first supermassive black holes

2019 ◽  
Vol 36 ◽  
Author(s):  
Tyrone E. Woods ◽  
Bhaskar Agarwal ◽  
Volker Bromm ◽  
Andrew Bunker ◽  
Ke-Jung Chen ◽  
...  
Keyword(s):  
Black Holes ◽  
Early Universe ◽  
Supermassive Black Holes ◽  
Considerable Progress ◽  
Next Generation ◽  
Theoretical Understanding ◽  
Theoretical Evidence ◽  
Present Understanding ◽  
Insight Into ◽  
Made In

Abstract In recent years, the discovery of massive quasars at $z\sim7$ has provided a striking challenge to our understanding of the origin and growth of supermassive black holes in the early Universe. Mounting observational and theoretical evidence indicates the viability of massive seeds, formed by the collapse of supermassive stars, as a progenitor model for such early, massive accreting black holes. Although considerable progress has been made in our theoretical understanding, many questions remain regarding how (and how often) such objects may form, how they live and die, and how next generation observatories may yield new insight into the origin of these primordial titans. This review focusses on our present understanding of this remarkable formation scenario, based on the discussions held at the Monash Prato Centre from November 20 to 24, 2017, during the workshop ‘Titans of the Early Universe: The Origin of the First Supermassive Black Holes’.

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