Early Biological Evolution Derived from Chemical Structures

1980 ◽  
pp. 71-86
Author(s):  
M. O. Dayhoff ◽  
R. M. Schwartz
Keyword(s):  
Biological Evolution ◽  
Chemical Structures

The Tempo and mode(S) of Prebiotic Evolution

1997 ◽  
Vol 161 ◽  
pp. 419-429 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Organic Compounds ◽  
Biological Evolution ◽  
Current Evidence ◽  
Early Diversification ◽  
Time Period ◽  
The Galaxy ◽  
History Of ◽  
Widespread Phenomenon ◽  
The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

Chemical structure of diamond-like carbon thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 710-711
Author(s):  
N.-H. Cho ◽  
K.M. Krishnan ◽  
D.B. Bogy
Keyword(s):  
Electrical Resistivity ◽  
Chemical Structure ◽  
Diamond Like Carbon ◽  
Chemical Structures ◽  
Sputtering Power ◽  
Data Aquisition ◽  
Equilibrium Phases ◽  
Electron Energy Loss ◽  
Power Densities ◽  
Preparation Techniques

Diamond-like carbon (DLC) films have attracted much attention due to their useful properties and applications. These properties are quite variable depending on film preparation techniques and conditions, DLC is a metastable state formed from highly non-equilibrium phases during the condensation of ionized particles. The nature of the films is therefore strongly dependent on their particular chemical structures. In this study, electron energy loss spectroscopy (EELS) was used to investigate how the chemical bonding configurations of DLC films vary as a function of sputtering power densities. The electrical resistivity of the films was determined, and related to their chemical structure.DLC films with a thickness of about 300Å were prepared at 0.1, 1.1, 2.1, and 10.0 watts/cm2, respectively, on NaCl substrates by d.c. magnetron sputtering. EEL spectra were obtained from diamond, graphite, and the films using a JEOL 200 CX electron microscope operating at 200 kV. A Gatan parallel EEL spectrometer and a Kevex data aquisition system were used to analyze the energy distribution of transmitted electrons. The electrical resistivity of the films was measured by the four point probe method.

The essence of biological evolution

1984 ◽  
Vol 143 (7) ◽  
pp. 429 ◽  
Author(s):  
M.V. Vol'kenshtein
Keyword(s):  
Biological Evolution

The essence of biological evolution

1983 ◽  
Vol 141 (11) ◽  
pp. 546 ◽  
Author(s):  
M.V. Vol'kenshtein
Keyword(s):  
Biological Evolution

Chemical Structures and their Properties of Wood Components

2013 ◽  
Vol 67 (10) ◽  
pp. 1131-1136
Author(s):  
Toshiyuki Takano
Keyword(s):  
Chemical Structures

Unzipping Natural Products: Improved Natural Product Structure Predictions by Ensemble Modeling and Fingerprint Matching

2018 ◽  
Author(s):  
William A. Shirley ◽  
Brian P. Kelley ◽  
Yohann Potier ◽  
John H. Koschwanez ◽  
Robert Bruccoleri ◽  
...  
Keyword(s):  
Natural Products ◽  
Open Source ◽  
Natural Product ◽  
Gene Cluster ◽  
Public Domain ◽  
Product Structure ◽  
Fingerprint Matching ◽  
Ensemble Modeling ◽  
Chemical Structures ◽  
Source Gene

This pre-print explores ensemble modeling of natural product targets to match chemical structures to precursors found in large open-source gene cluster repository antiSMASH. Commentary on method, effectiveness, and limitations are enclosed. All structures are public domain molecules and have been reviewed for release.

Change of quality indexes of premixes in the storage process

2020 ◽  
pp. 105-112
Author(s):  
Oksana Bitlian ◽  
Oksana Kravchenko ◽  
Tetiana Kodak ◽  
Andrii Onyshchenko ◽  
Tetiana Konks
Keyword(s):  
Raw Materials ◽  
Storage Process ◽  
Important Place ◽  
Inappropriate Use ◽  
Chemical Structures ◽  
Copper Zinc ◽  
Qualitative Responses ◽  
Chelating Compounds ◽  
Quality Indexes

The analysis of literature sources shows that the type and material from which the packaging is made has an important place in the system of factors which influence on the storage of feed products and also prevents reducing the quality of raw materials and finished products. Therefore, the purpose of our research is the technological justification of changing the quality indexes of premix samples with salts of trace elements of different chemical nature in the process of storage. For the solution of the tasks, common zootechnical and statistical methods of the research were used. The use of premixes in feeding pigs is based on the fact that they should be used taking into account the biogeochemical properties of the region for which they are calculated. Foods depending on regional properties have a special biochemical composition and excess or lack of individual substances should be offset by the composition of premix. Ignoring this provision necessarily leads to the inappropriate use of BAR, the misbalance of the diet in relation to the physiological needs and inefficiency of the industry. In turn, it requires the purchase and conservation of products for the period of use. Various chemical structures and structures of BAR during the storage process react differently and change qualitative indexes, which leads to a decrease in the productive activity of active substances. It was determined that the humidity of premixes varied within the limits of 12.0-13.0 %, which exceeded the normative, but was not critical, the highest acidity had premix with sulfuric acid salts (6.9 units), the least - premix with lysates (5.7 unit). According to the results of the study, positive qualitative responses were found for the presence of vitamins A, D and B2, macro- and micronutrients: potassium, magnesium, copper, zinc, cobalt, iodine. The above facts of changes in the properties of premixes in the process of storage must be taken into account when providing technological bases for feeding pigs in order to obtain high gains and the quality of manufactured products. Key words: premix, micro-and macro elements, combined fodders, fodder mixes, chelating compounds, feeding, using, pigs' livestock.

Synthesis, Characterization and Thermal Degradation of Some New 3,5-dimethyl Pyrazole Derivatives

2017 ◽  
Vol 68 (2) ◽  
pp. 317-322
Author(s):  
Anca Mihaela Mocanu ◽  
Constantin Luca ◽  
Alina Costina Luca
Keyword(s):  
Thermal Degradation ◽  
Degradation Mechanism ◽  
New Products ◽  
Analysis Data ◽  
Biological Properties ◽  
Elemental Analysis Data ◽  
Ftir Analysis ◽  
Spectral Measurements ◽  
Chemical Structures ◽  
And Storage

The purpose of this research is to synthetize, characterize and thermal degradation of new heterolytic derivates with potential biological properties. The derivates synthesis was done by obtaining new molecules with pyralozone structure which combine two pharmacophore entities: the amidosulfonyl-R1,R2 phenoxyacetil with the 3,5-dimethyl pyrazole which can have potential biological properties. The synthesis stages of the new products are presented as well as the elemental analysis data and IR, 1H-NMR spectral measurements made for elucidating the chemical structures and thermostability study which makes evident the temperature range proper for their use and storage. The obtained results were indicative of a good correlation of the structure with the thermal stability as estimated by means of the initial degradation temperatures as well as with the degradation mechanism by means of the TG-FTIR analysis.

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