scholarly journals Dynamics of physical-chemical transformations at Eastern Donbass siltstones firing

2019 ◽  
Author(s):  
Kh. S. Yavruyan ◽  
V. D. Kotlyar ◽  
E. S. Gayshun ◽  
A. S. Okhotnaya ◽  
G. O. Budagyants ◽  
...  
Keyword(s):  
Chemical Transformations ◽  
Physical Chemical

Physical-Chemical Investigations of Artificial Rubber

1942 ◽  
Vol 15 (4) ◽  
pp. 854-859
Author(s):  
A. Springer
Keyword(s):  
Degree Of Polymerization ◽  
Polymerization Process ◽  
Chemical Transformations ◽  
Thermal Methods ◽  
Chain Molecules ◽  
Physical Chemical ◽  
Thermal Measurements ◽  
Heats Of Combustion ◽  
The Difference ◽  
Energy Relations

Abstract Among the physical methods of which use has been made to explain the structure of organic compounds, thermal measurements, particularly measurements of heats of combustion, have played a particularly important part. With the aid of data on heats of combustion, it is possible to draw conclusions on the energy relations within molecules and on the heat tones of chemical transformations. Such measurements have been carried out on highly polymeric substances. In some cases, the object was to study the reactions of formation. e.g., polymerization; in other cases it was to explain the transformations which high polymers themselves undergo. Studies of polymerization reactions by thermal methods have shown that, in distinction to monomers, a decrease in the heat of combustion with increase in the degree of polymerization is to be expected. The polymerization process is accordingly exothermic, and the difference between the heats of combustion represents the heat of polymerization which is liberated. A direct comparison of heats of polymerization found experimentally by different investigators is, however, not possible because, in most cases, no information on the degree of polymerization, branching of the chain molecules, or other significant properties of the polymers are given.

scholarly journals Post-deposition Weathering of Pb-rich Particles From a Pb-Zn Smelting and Refining Factory Under Semiarid Conditions

2021 ◽  
Author(s):  
Martin Federico Soto-Jiménez ◽  
Sarahi Roos-Muñoz ◽  
Sarahi Soto-Morales ◽  
Laura Elena Gómez-Lizarrága ◽  
Lauro Bucio-Galindo
Keyword(s):  
Electron Microscopy ◽  
Chemical Transformations ◽  
Urban Dust ◽  
X Ray ◽  
Physical Chemical ◽  
The World ◽  
Post Deposition ◽  
Mineral Identification ◽  
Scanning Electron ◽  
Semiarid Conditions

Abstract In this study, urban dust samples were collected at 1 km radius surrounding one of the largest Ag-Cd-Pb-Zn smelting and refining complex in the world (Met-Mex Peñoles), which is in operation in Torreón (North México) since 1901. Metal-rich particles in urban dust were analyzed for elemental composition, and Pb-rich particles were identified, characterized, and analyzed for mineral identification by using conventional techniques such as scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), and X-ray powder diffraction (XRD). Pb-rich particles showed a variety of sizes and morphologies and different contents of Pb and other elements. Pb-rich particles were related to the fugitive and non-controlled emissions from Met-Mex Peñoles. Galena occurs in individual and metal-rich agglomerate particles. The presence of secondary Pb minerals (e.g., Pb carbonates, Pb sulfate, and Pb oxides) evidenced the weathering in Pb-rich particles and metal-rich agglomerates. Secondary Pb minerals are incorporated in finer particles than original sulfide minerals, and they are also more concentrated in Pb and chemically more available than galena for the environment and humans. Physical-chemical transformations on the weathered Pb-rich particles are increasing the availability and toxicity of lead in the urban dust and the potential impacts on the environment and human health.

Equation of state and physical–chemical transformations of C60 fullerite at high pressures and temperatures

2007 ◽  
Vol 16 (4-7) ◽  
pp. 1204-1207 ◽  
Author(s):  
K.V. Khishchenko ◽  
V.V. Milyavskiy ◽  
A.V. Utkin ◽  
V.V. Yakushev ◽  
A.Z. Zhuk ◽  
...  
Keyword(s):  
Equation Of State ◽  
High Pressures ◽  
Chemical Transformations ◽  
Physical Chemical ◽  
High Pressures And Temperatures

scholarly journals Physical-chemical transformations in the system V2O5/(NH4)2Mo2O7 under hydrothermal conditions

2014 ◽  
Vol 12 (2) ◽  
pp. 140-152 ◽  
Author(s):  
Svitlana Khalameida ◽  
Volodymyr Sydorchuk ◽  
Roman Leboda ◽  
Jadwiga Skubiszewska-Zięba ◽  
Valery Zazhigalov
Keyword(s):  
Phase Transformations ◽  
Aqueous Medium ◽  
Nitrogen Adsorption ◽  
Chemical Transformations ◽  
Macroporous Structure ◽  
Hydrothermal Conditions ◽  
Physical Chemical ◽  
Vis Spectroscopy ◽  
Catalytically Active

AbstractModified compositions in the system V2O5/(NH4)2Mo2O7 have been prepared by means of mechanochemical, hydrothermal, microwave and ultrasonic treatments in aqueous medium. Chemical and phase transformations occurring on the stages of modification and following calcinations have been studied with the help of XRD, DTA-TG, FTIR and UV-Vis spectroscopy, nitrogen adsorption, and SEM. It has been established that precursors of catalytically active phases possessing meso-macroporous structure have been formed during modification. The comparison of the properties of compositions prepared via different methods has been carried out. Particularly, precursors modified via various procedures possess different morphology.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

Seeking to uncover biology's chemical roots

2019 ◽  
Vol 3 (5) ◽  
pp. 435-443 ◽  
Author(s):  
Addy Pross
Keyword(s):  
Environmental Changes ◽  
Biological Systems ◽  
Significant Development ◽  
The Road ◽  
Physical Chemical ◽  
Systems Chemistry ◽  
Biological World ◽  
Inanimate Matter ◽  
The Origin Of Life ◽  
Opening Up

Despite the considerable advances in molecular biology over the past several decades, the nature of the physical–chemical process by which inanimate matter become transformed into simplest life remains elusive. In this review, we describe recent advances in a relatively new area of chemistry, systems chemistry, which attempts to uncover the physical–chemical principles underlying that remarkable transformation. A significant development has been the discovery that within the space of chemical potentiality there exists a largely unexplored kinetic domain which could be termed dynamic kinetic chemistry. Our analysis suggests that all biological systems and associated sub-systems belong to this distinct domain, thereby facilitating the placement of biological systems within a coherent physical/chemical framework. That discovery offers new insights into the origin of life process, as well as opening the door toward the preparation of active materials able to self-heal, adapt to environmental changes, even communicate, mimicking what transpires routinely in the biological world. The road to simplest proto-life appears to be opening up.

Sign in / Sign up

Export Citation Format

Share Document