scholarly journals The Role of Calcium and Strontium as the Most Dominant Elements during Combinations of Different Alkaline Earth Metals in the Synthesis of Crystalline Silica-Carbonate Biomorphs

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 381 ◽  
Author(s):  
Mayra Cuéllar-Cruz ◽  
Abel Moreno
Keyword(s):  
Alkaline Earth ◽  
Chemical Elements ◽  
Living Organism ◽  
Life Forms ◽  
Point Of View ◽  
Alkaline Earth Metals ◽  
Evolution Of Life ◽  
Living Organisms ◽  
The Stability

The origin of life from the chemical point of view is an intriguing and fascinating topic, and is of continuous interest. Currently, the chemical elements that are part of the different cellular types from microorganisms to higher organisms have been described. However, although science has advanced in this context, it has not been elucidated yet which were the first chemical elements that gave origin to the first primitive cells, nor how evolution eliminated or incorporated other chemical elements to give origin to other types of cells through evolution. Calcium, barium, and strontium silica-carbonates have been obtained in vitro and named biomorphs, because they mimic living organism structures. Therefore, it is considered that these forms can resemble the first structures that were part of primitive organisms. Hence, the objective of this work was to synthesize biomorphs starting with different mixtures of alkaline earth metals—beryllium (Be2+), magnesium (Mg2+), calcium (Ca2+), barium (Ba2+), and strontium (Sr2+)—in the presence of nucleic acids, RNA and genomic DNA (gDNA). Our results allow us to infer that the stability of calcium followed by strontium had played an important role in the evolution of life since the Precambrian era until our current age. In this way, the presence of these two chemical elements as well as silica (in the primitive life) and some organic molecules give origin to a great variety of life forms, in which calcium is the most common dominating element in many living organisms as we know nowadays.

The influence of X-rays on the stability of selected properties of polyethylene

2018 ◽  
Vol 23 (1) ◽  
pp. 3-11
Author(s):  
Anna Wiśniewska ◽  
Gabriela Chwalik ◽  
Sylwia Łagan
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Living Organism ◽  
Degradation Process ◽  
Material Surface ◽  
Control Group ◽  
X Rays ◽  
X Ray ◽  
The Stability

The evaluation of a degradation process of polyethylene (PE) in in vitro conditions under the influence of X-rays (X) and an in-cubation in two solutions simulating the environment of a living organism (SBF – simulated body fluid) was carried out. A dose corresponding to 10 standard X-ray pictures of the skeletal system as well as Ringer's and saline solutions at 40°C were used in the study. The paper presents the results of the influence of the 12-month studies on the selected surface properties of the material: surface wettability and abrasiveness. The value of surface free energy (SFE) was determined on the basis of the wetting angle measurements. The conductivity of the incubation fluids was also analyzed. The obtained results indicate that the adopted dose of X-ray radiation has no significant effect on the wettability of the surface of polyethylene. The nature of the surface layer of polyethylene did not change as a result of the 12-month incubation and remained hydrophilic. For the samples incubated in both immersion fluids, a decrease in surface free energy (SFE) was observed. For both the irradiated material and the control group, no significant changes in the mass of the samples and the conductivity of the incubation fluids were found, which indicates the stability of polyethylene. However, the abrasion value increased by approximately 26%. With the passage of the incubation time, a decrease in the value of this parameter was observed for the polyethylene subjected to radiation. No significant changes were found for the control group.

scholarly journals Complexes of Rare- and Alkaline-Earth Elements in Catalytic Intermolecular Hydrophosphination of Multiple C—C Bonds

Vestnik RFFI ◽  
2019 ◽  
pp. 58-73
Author(s):  
Ivan V. Lapshin ◽  
Alexander A. Kissel ◽  
Alexander A. Trifonov
Keyword(s):  
Rare Earth ◽  
Alkaline Earth ◽  
Organophosphorus Compounds ◽  
Chemical Elements ◽  
Earth Metal ◽  
Alkaline Earth Metals ◽  
Lewis Acidity ◽  
Synthetic Approach ◽  
Ionic Radii ◽  
Late Transition Metals

In accordance with United Nations General Assembly resolution, the year 2019 was proclaimed the International Year of the Periodic Table of Chemical Elements. Rare-earth elements were discovered during the time of the Periodic System development. In the past few decades, their compounds have attracted great interest due to their unique reactivity. This review covers recent achievements in the field of intermolecular hydrophosphination of alkenes, dienes and alkynes, which is catalyzed by rare earth and alkaline-earth metal complexes. Catalytic hydrophosphination reaction is the addition of an P—H bond to С—С multiple bonds, and offers an efficient and elegant synthetic approach to production of the organophosphorus compounds widely used in industrial synthesis, pharmaceuticals, agrochemistry, and other areas. The high values of the ionic radii of rare earth and alkaline-earth metals in combination with the Lewis acidity provide their compounds with a pronounced tendency to complex formation and, accordingly, high coordination numbers. Due to high reactivity of M—E (E = C, H, N, P) bonds, ease of Ln—P ı-bond metathesis and multiple C—C bond insertions, these compounds offer new prospects for the catalysis of the alkenes and alkynes hydrophosphination. Therefore, complexes of non-toxic and relatively abundant in nature rare earth and alkaline earth metals can be a cheaper and more effective alternative to compounds of late transition metals in the catalysis of the C—P bond formation.

scholarly journals Aptamers in the Treatment of Bacterial Infections: Problems and Prospects

2016 ◽  
Vol 71 (5) ◽  
pp. 350-358
Author(s):  
N. A. Zeninskaya ◽  
A. V. Kolesnikov ◽  
A. K. Ryabko ◽  
I. G. Shemyakin ◽  
I. A. Dyatlov ◽  
...  
Keyword(s):  
Drug Discovery ◽  
High Throughput Screening ◽  
Bacterial Infections ◽  
Point Of View ◽  
Aptamer Selection ◽  
Wide Range ◽  
Therapeutic Molecules ◽  
Molecular Selection ◽  
The Stability

Aptamers are short single-stranded oligonucleotides which are selected via targeted chemical evolution in vitro to bind a molecular target of interest. The aptamer selection technology is designated as SELEX (Systematic evolution of ligands by exponential enrichment). SELEX enables isolation of oligonucleotide aptamers binding a wide range of targets of interest with little respect for their nature and molecular weight. A number of applications of aptamer selection were developed ranging from biosensor technologies to antitumor drug discovery. First aptamer-based pharmaceutical (Macugen) was approved by FDA for clinical use in 2004, and since then more than ten aptamer-based drugs undergo various phases of clinical trials. From the medicinal chemist’s point of view, aptamers represent a new class of molecules suitable for the development of new therapeutics. Due to the stability, relative synthesis simplicity, and development of advanced strategies of target specific molecular selection, aptamers attract increased attention of drug discovery community. Difficulties of the development of next-generation antibiotics basing on the conventional basis of combinatorial chemistry and high-throughput screening have also amplified the interest to aptamer-based therapeutic candidates. The present article reviews the investigations focused on the development of antibacterial aptamers and discusses the potential and current limitations of the use of this type of therapeutic molecules.

scholarly journals Stability and Optical Absorption of a Comprehensive Virtual Library of Minimal Eumelanin Oligomer Models

2021 ◽  
Author(s):  
jun wang ◽  
Lluís Blancafort
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Level Structure ◽  
Point Of View ◽  
Chemical Diversity ◽  
Quinone Methide ◽  
Minimal Models ◽  
Functional Theory ◽  
Living Organisms ◽  
The Stability

Eumelanin is the black biopolymer responsible for photoprotection in living organisms. Lack of knowledge of the atomic-level structure limits understanding of its function and exploitation of its potential in material science. To overcome these limitations, we present a systematic density functional theory study of the stability and optical properties of a library of 830 dimers of 5,6-dihydroxyindole (DHI), which are minimal models of eumelanin oligomers. Our aim is to understand the principles that govern the formation of DHI oligomers, relate the optical properties of the dimers with their stability, and establish their possible role in the photophysics of the biopolymer. From the structural point of view, we find a preference for oxidized over reduced and cyclic over linear structures, which speaks in favor of polycyclic graphite-like structures for the larger oligomers. We present an electrocyclization mechanism leading to the cyclic structures. We also find that besides the widely considered quinone and quinone methide oxidation patterns where two heteroatoms per DHI fragment are oxidized, dimers with one or three oxidized sites per fragment and an interfragment double bond are also stable and may be present in eumelanin. As far as the optical properties are concerned, some oxidized dimers combine relative stability with absorption energies as low as 1.3 eV. Such fragments may be present as substructures in the naturally found oligomers and might have a relevant contribution to the absorption spectrum of the biopolymer. In addition to these insights into the struc-tural and optical properties of the oligomers, we introduce a new classification scheme and a representative set of 53 dimers combining thermodynamic stability with chemical diversity.<br>

scholarly journals Mechanizmy śmierci od komórki do całego organizmu

2019 ◽  
Author(s):  
Sylwia Ciesielska
Keyword(s):  
Cell Death ◽  
Living Organism ◽  
Cell Types ◽  
In Vivo Studies ◽  
Whole Body ◽  
Natural Phenomenon ◽  
Human Organism ◽  
Living Organisms

In vitro studies are alternative for in vivo studies carried on living organisms. They involve cell populations for both normal and cancer cells. The processes inside cells might be base for defining whole body processes. Starting with fundamental unit of every living organism which is cell, we can distinguish two main types of cell death – apoptosis and necrosis. Human organism is built from 1013–1014 cells of 300 different cell types. During cell division new cells are created and their number is strictly controlled in programmed cell death – apoptosis. Mainly old or damaged cells commit suicide and are removed from organism. This is natural phenomenon and every change in mechanisms of proliferation or apoptosis cause changes and damage in whole organism. Homeostasis in organism depends on correct action of death and survival system. The patterns of equilibrium in nature relies on similar regulation profiles, in which it is similar to death of singular organisms in population or species. It implicates death as natural phenomenon maintaining balance in the world.

scholarly journals BUILDING BLOCKS OF LIFE IN METEORITES MAY LEAD TO PANSPERMIA ORIGIN OF LIFE

2021 ◽  
Vol 9 (11) ◽  
pp. 235-251
Author(s):  
Y. V. Subba Rao
Keyword(s):  
Origin Of Life ◽  
Electromagnetic Force ◽  
Building Blocks ◽  
Life Forms ◽  
Biological Molecules ◽  
Evolution Of Life ◽  
Living Organisms ◽  
Definition Of ◽  
Life On Earth ◽  
The Universe

              The current hypothesis leads to the panspermia origin of life, which is based on the scientific principle of electromagnetic force interaction with matter. Electromagnetic force (Sunlight) interacts with inorganic chemistry available to us given out by the stars in the universe plausibly triggers the formation of extra-terrestrial biological molecules of proto cells under abiotic conditions, as evidenced by their presence in meteorites.' Proto cells’ might theoretically give rise to living organisms with a manifested soul, allowing 'Ribose' to be formed from ice grains hit by sunlight for RNA and DNA at the same time. The presence of life's building blocks and other important organic chemicals like ribose in meteorites, including some microscopic life forms that aren't native to Earth, may have led to the 'Panspermia Origin of Life' and the 'Evolution of Life on Earth' which is evidenced by the definition of 'Meteorites' in Vedic Scriptures, such as the "Bhagavad Gita" (3000 BC) and "Brihat Samhita" (520 AD) that they are the souls of righteous people who have returned to earth to be reborn.

Contribution to the Physical Chemistry of Hevea Latex. II. Adsorption of Metallic Cations on the Surface of Latex Particles. Distribution of Alkali Metals, Alkaline Earth Metals, and Iron between the Two Phases of Latex Preserved with Ammonia

1952 ◽  
Vol 25 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Robert Belmas
Keyword(s):  
Alkali Metals ◽  
Alkaline Earth ◽  
Organic Anion ◽  
Complex Structure ◽  
Living Organism ◽  
Alkaline Earth Metals ◽  
Adsorption Equilibria ◽  
Negative Surface ◽  
Metallic Cations ◽  
Two Phases

Abstract The study of latex is characterized by the fact that it is always difficult to draw any definite conclusions. One is confronted with a substance which has been synthesized by a living organism, and whose extremely complex structure is very different from that of the sols currently studied by colloid chemistry. However, ultracentrifugation makes it possible to obtain reliable results as far as partition of the natural metallic components between the dispersing and dispersed phases is concerned. The existence of equilibria of adsorption as a function of the dilution of latex and comparison of the experimental curves with the isotherms of Freundlich and of Langmuir shows that, in the case of latex, adsorption is not a simple phenomenon. At least two different processes seem to be involved: (1) electrosorption of the metallic cations by the negative surface of the rubber particles, and (2) indirect adsorption, whereby the metal is bound in a slightly dissociable form to an organic anion which is itself strongly adsorbed. This would explain the much weaker adsorption of the alkali metals, which possess only a positive charge, and whose salts are in general more easily dissociated than those of the alkaline earth metals. The results obtained for metals added to latex in the form of soluble salts lead to the same conclusions. Measurement of the adsorption equilibria for samples of latex containing different concentrations of rubber show that, the smaller the proportion of dispersing phase to dispersed phase, the higher is the adsoprtion. This phenomenon, which is evident with alkali metals as well as with alkaline earth metals, can be explained by the increase of the charge on the particles when the latex is diluted. An examination of the critical adsorption values for the different metals studied confirms the fact that the behavior of latex with salts is that of a mixed sol with both lyophilic and lyophobic properties. These results would be more valuable if confirmed and determined more precisely by an electrokinetic study. The determination of the potential of the particles by measuring the cataphoretic velocity with respect to the adsorption of metal ions would surely permit a more accurate interpretation of the mechanism of this adsorption.

Athermochemical Investigation of the La-Sr-Cu-O System

1989 ◽  
Vol 169 ◽  
Author(s):  
Joseph Bularzik ◽  
Alexandra Navrotsky ◽  
Bruce Scott ◽  
Joe Bringley ◽  
Steve Trail
Keyword(s):  
High Temperature ◽  
Alkaline Earth ◽  
High Temperature Superconductors ◽  
Solution Calorimetry ◽  
Alkaline Earth Metals ◽  
Heats Of Formation ◽  
High Temperature Solution ◽  
Calorimetric Measurements ◽  
Temperature Solution ◽  
The Stability

AbstractThe perovskite related La2‐xMxCuO4‐y oxides substituted with alkaline earth metals were one of the first classes of high temperature superconductors discovered. Determining the thermodynamic properties is important to understand the stability and superconducting mechanism of these structures. High temperature solution calorimetry, using a molten lead borate solvent, has been performed on La2CuO4 and the related Sr substituted oxides. Calorimetric measurements on CuO, La2O3 and SrCO3 yield heats of formation. A change in the trend of the heats of formation appears at Sr content 0.1, the reported orthorhombic to tetragonal transition, the onset of superconductivity and loss of oxygen.

ON THE PHYSICO-CHEMICAL THEORY OF BIOLOGICAL EVOLUTION

1996 ◽  
Vol 04 (02) ◽  
pp. 239-247
Author(s):  
G.P. GLADYSHEV ◽  
D.P. GLADYSHEV
Keyword(s):  
Self Assembly ◽  
Biological Evolution ◽  
Life Forms ◽  
Gibbs Function ◽  
Experimental Identification ◽  
Chemical Theory ◽  
Physico Chemical ◽  
Evolution Of Life ◽  
Living Organisms ◽  
Relative Thermodynamic Stability

The present paper deals with the experimental identification of previously postulated correlations linking the specific Gibbs function of the formation of supramolecular structures of living organisms with the chemical energy capacity or the relative thermodynamic stability of the substances involved in the self-assembly of these structures. The paper presents new results to further corroborate the macrothermodynamic model of the evolution of biological systems as applied to phylogenesis, ontogenesis as well as the extended periods of the general evolution of life forms.

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