THERMAL SOLUTIONS FOR MOLECULAR EVOLUTION

2012 ◽  
Vol 26 (32) ◽  
pp. 1230017 ◽  
Author(s):  
CHRISTOF B. MAST ◽  
NATAN OSTERMAN ◽  
DIETER BRAUN
Keyword(s):  
Molecular Evolution ◽  
Thermal Gradient ◽  
Soret Effect ◽  
Convection Flow ◽  
Thermal Gradients ◽  
Temperature Oscillations ◽  
The Origin Of Life ◽  
High Concentrations ◽  
The One ◽  
Further Development

The key requirement to solve the origin of life puzzle are disequilibrium conditions. Early molecular evolution cannot be explained by initial high concentrations of energetic chemicals since they would just react towards their chemical equilibrium allowing no further development. We argue here that persistent disequilibria are needed to increase complexity during molecular evolution. We propose thermal gradients as the disequilibrium setting which drove Darwinian molecular evolution. On the one hand the thermal gradient gives rise to laminar thermal convection flow with highly regular temperature oscillations that allow melting and replication of DNA. On the other hand molecules move along the thermal gradient, a mechanism termed Soret effect or thermophoresis. Inside a long chamber a combination of the convection flow and thermophoresis leads to a very efficient accumulation of molecules. Short DNA is concentrated thousand-fold, whereas longer DNA is exponentially better accumulated. We demonstrated both scenarios in the same micrometer-sized setting. Forthcoming experiments will reveal how replication and accumulation of DNA in a system, driven only by a thermal gradient, could create a Darwinian process of replication and selection.

Toward living nanomachines

2018 ◽  
Author(s):  
Christof Mast ◽  
Friederike Möller ◽  
Moritz Kreysing ◽  
Severin Schink ◽  
Benedikt Obermayer ◽  
...  
Keyword(s):  
Molecular Evolution ◽  
Thermal Gradient ◽  
Molecular Level ◽  
Minimal System ◽  
Thermal Gradients ◽  
Temperature Oscillations ◽  
Fluid Convection ◽  
Inanimate Matter ◽  
High Concentrations ◽  
Periodic Temperature

How does inanimate matter become transformed into animate matter? Living systems evolve by replication and selection at the molecular level and this chapter considers how to establish a synthetic, minimal system that can support molecular evolution and thus life. Molecular evolution cannot be explained by starting with high concentrations of activated chemicals that react toward their chemical equilibrium; persistent non-equilibria are required to maintain continuous reactivity and we especially consider thermal gradients as an early driving force for Darwinian molecular evolution. The temperature difference across water-filled compartments implements a laminar fluid convection with periodic temperature oscillations that allow for the melting and replication of DNA. Simultaneously, dissolved molecules are moved along the thermal gradient by an effect called thermophoresis. The combined result is an efficient molecule trap that exponentially favors long over short DNA and thus maintains complexity. Future experiments will reveal how thermal gradients could actively drive the Darwinian process of replication and selection.

Fission Gas Bubbles in Fractured UO2

1968 ◽  
Vol 26 ◽  
pp. 286-287
Author(s):  
O. M. Katz
Keyword(s):  
Electron Microscopy ◽  
Thermal Gradient ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Thermal Gradients ◽  
Fission Gas ◽  
Beam Heating ◽  
Limited Application ◽  
Bubble Characteristics ◽  
Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

scholarly journals Small-Scale Spectrum of a Scalar Field in Water: The Batchelor and Kraichnan Models

2011 ◽  
Vol 41 (11) ◽  
pp. 2155-2167 ◽  
Author(s):  
Xavier Sanchez ◽  
Elena Roget ◽  
Jesus Planella ◽  
Francesc Forcat
Keyword(s):  
Scalar Field ◽  
Thermal Gradient ◽  
Theoretical Models ◽  
Measured Data ◽  
Small Scale ◽  
Temperature Profiles ◽  
One Dimensional ◽  
Kraichnan Model ◽  
The One ◽  
Rate Of Dissipation

Abstract The theoretical models of Batchelor and Kraichnan, which account for the smallest scales of a scalar field passively advected by a turbulent fluid (Prandtl > 1), have been validated using shear and temperature profiles measured with a microstructure profiler in a lake. The value of the rate of dissipation of turbulent kinetic energy ɛ has been computed by fitting the shear spectra to the Panchev and Kesich theoretical model and the one-dimensional spectra of the temperature gradient, once ɛ is known, to the Batchelor and Kraichnan models and from it determining the value of the turbulent parameter q. The goodness of the fit between the spectra corresponding to these models and the measured data shows a very clear dependence on the degree of isotropy, which is estimated by the Cox number. The Kraichnan model adjusts better to the measured data than the Batchelor model, and the values of the turbulent parameter that better fit the experimental data are qB = 4.4 ± 0.8 and qK = 7.9 ± 2.5 for Batchelor and Kraichnan, respectively, when Cox ≥ 50. Once the turbulent parameter is fixed, a comparison of the value of ɛ determined from fitting the thermal gradient spectra to the value obtained after fitting the shear spectra shows that the Kraichnan model gives a very good estimate of the dissipation, which the Batchelor model underestimates.

A Theoretical Study of the Temperature Gradient Effect on the Soret Coefficient in n-Pentane/n-Decane Mixtures Using Non-Equilibrium Molecular Dynamics

2020 ◽  
Vol 45 (4) ◽  
pp. 319-332
Author(s):  
Xiaoyu Chen ◽  
Ruquan Liang ◽  
Yong Wang ◽  
Ziqi Xia ◽  
Lichun Wu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Temperature Gradient ◽  
Thermal Gradient ◽  
Linear Response ◽  
Theoretical Study ◽  
Soret Coefficient ◽  
Thermal Gradients ◽  
Gradient Effect ◽  
Non Equilibrium Molecular Dynamics ◽  
Non Equilibrium

AbstractThe effect of the temperature gradient on the Soret coefficient in n-pentane/n-decane (n-C5/n-C10) mixtures was investigated using non-equilibrium molecular dynamics (NEMD) with the heat exchange (eHEX) algorithm. n-Pentane/n-decane mixtures with three different compositions (0.25, 0.5, and 0.75 mole fractions, respectively) and the TraPPE-UA force field were used in computing the Soret coefficient ({S_{T}}) at 300 K and 1 atm. Added/removed heat quantities (ΔQ) of 0.002, 0.004, 0.006, 0.008, and 0.01 kcal/mol were employed in eHEX processes in order to study the effect of different thermal gradients on the Soret coefficient. Moreover, a phenomenological description was applied to discuss the mechanism of this effect. Present results show that the Soret coefficient values firstly fluctuate violently and then become increasingly stable with increasing ΔQ (especially in the mixture with a mole fraction of 0.75), which means that ΔQ has a smaller effect on the Soret coefficient when the temperature gradient is higher than a certain thermal gradient. Thus, a high temperature gradient is recommended for calculating the Soret coefficient under the conditions that a linear response and constant phase are ensured in the system. In addition, the simulated Soret coefficient obtained at the highest ΔQ within three different compositions is in great agreement with experimental data.

scholarly journals The new international legal order and new states in the Balkans

2006 ◽  
Vol 58 (3) ◽  
pp. 272-293 ◽  
Author(s):  
Dusko Dimitrijevic
Keyword(s):  
International Law ◽  
Essential Role ◽  
Legal Order ◽  
State Behavior ◽  
The Balkans ◽  
Starting Point ◽  
New States ◽  
International Legal Order ◽  
The One ◽  
Further Development

In this study the author attaches a great importance to the theoretical examination of the concept of the New International Legal Order that was embodied in the last decades of the 20th century. The starting point for that reflection is the dissolution of the SFR Yugoslavia that illustrates one of the fundamental legal precedents. Reminding that the basic principle for the post-modern State behavior must be the one that includes minimal disturbance of the existing international legal relations, the author stresses that "the Yugoslav case" was customized in the way to respond to the new reality where the principle of effectiveness played an essential role in valuation of the statehood. It could also be one of the greatest catalysts for all further 'development rules' of international law.

scholarly journals DEVELOPMENT OF THE MODEL OF STUDENTS’ INDEPENDENT WORK UNDER CONDITIONS OF DISTANCE LEARNING

2021 ◽  
pp. 273-289
Author(s):  
Olena Osadcha
Keyword(s):  
Distance Learning ◽  
Information Technologies ◽  
The Other ◽  
Advantages And Disadvantages ◽  
Other Hand ◽  
The One ◽  
Independent Work ◽  
Further Development

The article deals with the development of the model of students’ independent work under conditions of distance learning. The importance of the research into this problem is determined, on the one hand, by the growing possibilities of using various information technologies and, on the other hand by the necessity to adapt to the conditions of today’s world where independent work of students is becoming increasingly important. The advantages and disadvantages of distance learning have been explored. The author studied the role of independent work in the formation of the professional competences of students. The issue of modeling in the area of education has been tackled. The approaches to the development of the model of independent work have been identified and analyzed. The components of the model, such as the goal, the tasks, the content, the methods, the means and evaluation of results have been determined and characterized. The prospects of further development of this research are related to the exploration of models of independent work of students majoring in different areas.

scholarly journals Problems and Prospects of Development of the International Market of Transport Services

2020 ◽  
pp. 305-312
Author(s):  
Oleksandr Dubytskyi ◽  
◽  
Vladimir Bodak ◽  
Nadiya Kuts ◽  
Yuri Bulik ◽  
...  
Keyword(s):  
Foreign Trade ◽  
Modern Science ◽  
International Market ◽  
Road Transport ◽  
Economic Relations ◽  
Transport Services ◽  
The World ◽  
Passenger Flows ◽  
The One ◽  
Further Development

The current situation in the world economy is characterized by varying degrees of development of national economies and their openness to participate in international economic relations, the saturation of trade flows at different stages of cooperation between countries, increasing passenger flows, on the one hand, and insufficient economic development. base, a small number of modern studies of the methodological basis for the functioning of the transport and logistics complex in modern science, on the other hand, cause an objective need for mentioned places, the role and importance of transport services as an important economic category. The structural shifts that determine the movement of world production and international trade are largely determined by the transformations taking place in the world transport complex. No foreign trade operation can be imagined without the participation of transport, in any case, the goods must be delivered from seller to buyer. Transport service - a service for the performance of the contract of carriage of people and goods. In the implementation of foreign trade, road transport has certain advantages over other modes of transport: maneuverability, delivery of goods "door to door"; urgency and regularity of delivery; delivery can be organized according to the system "just in time" (exactly on time); packaging (required in smaller quantities or not required at all). This article examines the trends and prospects for the development of the international market of transport services. The question of the current state of the freight market is stated. The main problems of the international market of transport services are clarified. The factors influencing the further development of the market of transport services are determined. Substantiated tasks in the field of international agreements in the field of road transport. The study allows us to consider and analyze important areas of innovative development and application of modern technologies in the field of transport. Prospects for further development of freight transportation are considered and generalized.

scholarly journals Changes in Quinone Profiles of Hot Spring Microbial Mats with a Thermal Gradient

1999 ◽  
Vol 65 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Akira Hiraishi ◽  
Taichi Umezawa ◽  
Hiroyuki Yamamoto ◽  
Kenji Kato ◽  
Yonosuke Maki
Keyword(s):  
Thermal Gradient ◽  
Microbial Mats ◽  
Hot Springs ◽  
Hot Spring ◽  
Thermal Gradients ◽  
Cyanobacterial Mats ◽  
Dissimilarity Index ◽  
Quinone Profile ◽  
Bacterial Mats ◽  
Different Temperatures

ABSTRACT The respiratory and photosynthetic quinones of microbial mats which occurred in Japanese sulfide-containing neutral-pH hot springs at different temperatures were analyzed by spectrochromatography and mass spectrometry. All of the microbial mats that developed at high temperatures (temperatures above 68°C) were so-called sulfur-turf bacterial mats and produced methionaquinones (MTKs) as the major quinones. A 78°C hot spring sediment had a similar quinone profile.Chloroflexus-mixed mats occurred at temperatures of 61 to 65°C and contained menaquinone 10 (MK-10) as the major component together with significant amounts of either MTKs or plastoquinone 9 (PQ-9). The sunlight-exposed biomats growing at temperatures of 45 to 56°C were all cyanobacterial mats, in which the photosynthetic quinones (PQ-9 and phylloquinone) predominated and MK-10 was the next most abundant component in most cases. Ubiquinones (UQs) were not found or were detected in only small amounts in the biomats growing at temperatures of 50°C and above, whereas the majority of the quinones of a purple photosynthetic mat growing at 34°C were UQs. A numerical analysis of the quinone profiles was performed by using the following three parameters: dissimilarity index (D), microbial divergence index (MDq ), and bioenergetic divergence index (BDq ). A D matrix tree analysis showed that the hot spring mats consisting of the sulfur-turf bacteria, Chloroflexus spp., cyanobacteria, and purple phototrophic bacteria formed distinct clusters. Analyses ofMDq and BDq values indicated that the microbial diversity of hot spring mats decreased as the temperature of the environment increased. The changes in quinone profiles and physiological types of microbial mats in hot springs with thermal gradients are discussed from evolutionary viewpoints.

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