The topochemistry of the reaction interface in decomposition processes in solids

1990 ◽  
Vol 8 (3-4) ◽  
pp. 211-230 ◽  
Author(s):  
Andrew K. Galwey
Keyword(s):  
Reaction Interface ◽  
Decomposition Processes

Interfacial studies in Nb3Sn superconductors

1991 ◽  
Vol 49 ◽  
pp. 590-591
Author(s):  
Ernest L. Hall ◽  
Lee E. Rumaner ◽  
Mark G. Benz
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Flux Pinning ◽  
Size Control ◽  
High Magnetic Fields ◽  
Type Ii ◽  
Reaction Interface ◽  
Liquid Diffusion ◽  
Type Ii Superconductor ◽  
Grain Size Control

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.

The Chemistry Decomposition in Human Corpses

2017 ◽  
Vol 68 (6) ◽  
pp. 1352-1356 ◽  
Author(s):  
Beatrice Gabriela Ioan ◽  
Cristiana Manea ◽  
Bianca Hanganu ◽  
Laura Statescu ◽  
Laura Gheuca Solovastru ◽  
...  
Keyword(s):  
Chemical Compounds ◽  
Human Remains ◽  
Organic Substances ◽  
Chemical Decomposition ◽  
Factors Influencing ◽  
Human Decomposition ◽  
Decomposition Processes ◽  
Human Cadavers ◽  
The Subject ◽  
Decomposition Stages

Human body is a complex of organic substances (proteins, lipids, carbohydrates), which undergo chemical decomposition processes soon after death. The compounds released during decomposition characterize the development of different stages of this process: e.g. biogenic amines resulted from the proteins decomposition will confer the particular smell of a cadaver, gases resulted from carbohydrates fermentation will give the bloating aspect of the cadaver. The study of cadaver decomposition and the products resulted from this process is the subject of human taphonomy and is realized nowadays in special facilities in USA and Australia. Identification and analysis of the chemical compounds emerged after human decomposition (gases, liquids, salts) give valuable information to forensic pathologists for estimating the postmortem interval (PMI). More, volatile compounds � which give the odor signature�specific to human remains � may be utilized in identifying clandestine burials, human remains or victims entrapped under ruins in cases of natural disasters. In this paper the authors describe the chemical decomposition stages of human cadavers, the factors influencing these processes and utility for the forensic activity of the results of human taphonomic studies.

Mass transfer in heterogeneous system enzyme-substrate; Approximate analytical model for the case of liquid substrate-immobilized enzyme

1982 ◽  
Vol 47 (11) ◽  
pp. 3013-3018
Author(s):  
František Kaštánek ◽  
Jindřich Zahradník ◽  
Germanico Ocampo
Keyword(s):  
Mass Transfer ◽  
Heterogeneous System ◽  
Immobilized Enzyme ◽  
Enzymatic Reaction ◽  
Analytical Form ◽  
Approximate Model ◽  
Basic Type ◽  
Reaction Interface ◽  
Enzyme Substrate ◽  
Flow Intensity

Calculation procedure is suggested for flow intensity of substrate toward reaction interface of immobilized enzyme at simultaneous effect of enzymatic reaction and internal diffusion. The approximate model is presented in an analytical form for the basic type of Michaelis-Menten kinetics and for the case of inhibition in excess of substrate.

A Thorough Investigation of Photo-catalytic Degradation of ortho and para-Nitro Phenols in binary mixtures: New Insights into Evaluating Degradations Progress Using Chemometrics Approaches

2021 ◽  
Author(s):  
S. Maryam Sajjadi ◽  
Zeinab Asadollah-pour ◽  
S. Hashem Sajjadi ◽  
S. Nasrin Nabavi ◽  
Zahra Abed ◽  
...  
Keyword(s):  
Binary Mixtures ◽  
Zno Nanoparticles ◽  
Catalytic Degradation ◽  
Solar Irradiation ◽  
Photo Catalyst ◽  
Decomposition Processes ◽  
Simulated Solar Irradiation ◽  
Photo Decomposition

In this study, photocatalytic degradations of 2-nitrophenol and 4-nitrophenol were carried out efficiently using ZnO nanoparticles photo-catalyst under simulated solar irradiation. The photo-decomposition processes were optimized simultaneously by employing central...

scholarly journals Anion Coordination Improves High-Temperature Performance and Stability of NaPF6-Based Electrolytes for Supercapacitors

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4409
Author(s):  
J. Landon Tyler ◽  
Robert L. Sacci ◽  
Jagjit Nanda
Keyword(s):  
Thermal Stability ◽  
Electrolyte Solution ◽  
Elevated Temperatures ◽  
Electrochemical Impedance ◽  
Cycle Life ◽  
Stable Complex ◽  
Complexing Agents ◽  
Anion Coordination ◽  
Decomposition Processes ◽  
Hexamethyl Phosphoramide

Electrolyte stability can be improved by incorporating complexing agents that bind key decomposition intermediates and slow down decomposition. We show that hexamethyl-phosphoramide (HMPA) extends both the thermal stability threshold of sodium hexafluorophosphate (NaPF6) in dimethoxyethane (DME) electrolyte and the cycle life of double-layer capacitors. HMPA forms a stable complex with PF5, an intermediate in PF6 anion thermal degradation. Unbound, this intermediate leads to autocatalytic degradation of the electrolyte solution. The results of electrochemical impedance spectroscopy (EIS) and galvanostatic cycling measurements show large changes in the cell without the presence of HMPA at higher temperatures (≥60 °C). Fourier transform infrared spectroscopy (FTIR) on the liquid and gas phase of the electrolyte shows without HMPA the formation of measurable amounts of PF5 and HF. The complimentary results of these measurements proved the usefulness of using Lewis bases such as HMPA to inhibit the degradation of the electrolyte solution at elevated temperatures and potentially lead to improve cycle life of a nonaqueous capacitor. The results showed a large increase in capacitance retention during cycling (72% retention after 750,000 cycles). The results also provide evidence of major decomposition processes (0% capacitance retention after 100,000 cycles) that take place at higher temperatures without the additive of a thermal stability additive such as HMPA.

scholarly journals Trace element catalyses mineral replacement reactions and facilitates ore formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yanlu Xing ◽  
Joël Brugger ◽  
Barbara Etschmann ◽  
Andrew G. Tomkins ◽  
Andrew J. Frierdich ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Trace Elements ◽  
Fluid Flow ◽  
Large Scale ◽  
Metal Accumulation ◽  
Nucleation And Growth ◽  
Reaction Interface ◽  
Ore Formation ◽  
Key Factor ◽  
Mineral Replacement

AbstractReaction-induced porosity is a key factor enabling protracted fluid-rock interactions in the Earth’s crust, promoting large-scale mineralogical changes during diagenesis, metamorphism, and ore formation. Here, we show experimentally that the presence of trace amounts of dissolved cerium increases the porosity of hematite (Fe2O3) formed via fluid-induced, redox-independent replacement of magnetite (Fe3O4), thereby increasing the efficiency of coupled magnetite replacement, fluid flow, and element mass transfer. Cerium acts as a catalyst affecting the nucleation and growth of hematite by modifying the Fe2+(aq)/Fe3+(aq) ratio at the reaction interface. Our results demonstrate that trace elements can enhance fluid-mediated mineral replacement reactions, ultimately controlling the kinetics, texture, and composition of fluid-mineral systems. Applied to some of the world’s most valuable orebodies, these results provide new insights into how early formation of extensive magnetite alteration may have preconditioned these ore systems for later enhanced metal accumulation, contributing to their sizes and metal endowment.

scholarly journals Carbons Formed in Methane Thermal and Thermocatalytic Decomposition Processes: Properties and Applications

2021 ◽  
Vol 7 (3) ◽  
pp. 50
Author(s):  
Emmi Välimäki ◽  
Lasse Yli-Varo ◽  
Henrik Romar ◽  
Ulla Lassi
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Production ◽  
Energy Systems ◽  
Hydrogen Gas ◽  
Solid Carbon ◽  
Hydrogen Economy ◽  
Decomposition Processes ◽  
Different Types ◽  
Decomposition Of Methane ◽  
Thermocatalytic Decomposition

The hydrogen economy will play a key role in future energy systems. Several thermal and catalytic methods for hydrogen production have been presented. In this review, methane thermocatalytic and thermal decomposition into hydrogen gas and solid carbon are considered. These processes, known as the thermal decomposition of methane (TDM) and thermocatalytic decomposition (TCD) of methane, respectively, appear to have the greatest potential for hydrogen production. In particular, the focus is on the different types and properties of carbons formed during the decomposition processes. The applications for carbons are also investigated.

scholarly journals Effect of Biofertilizers Application on Soil Biodiversity and Litter Degradation in a Commercial Apricot Orchard

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1116
Author(s):  
Elena Baldi ◽  
Paola Gioacchini ◽  
Daniela Montecchio ◽  
Stefano Mocali ◽  
Livio Antonielli ◽  
...  
Keyword(s):  
Nir Spectroscopy ◽  
Microbial Composition ◽  
Trichoderma Spp ◽  
Soil Biodiversity ◽  
Decomposition Processes ◽  
Dta Analysis ◽  
Litter Deposition ◽  
Litter Degradation ◽  
Bacteria And Fungi ◽  
One Year

The aim of the present experiment was to determine if the supply of biofertilizers could differently stimulate the native microbiota, thus determining different patterns of organic material decomposition processes. The microbial composition of soil and litter was investigated by next generation sequencing using a metabarcoding approach. The chemical structure of the decomposing litterbags was investigated through the TG-DTA analysis and NIR spectroscopy. The study was conducted in an apricot orchard in Italy, and two different type of biofertilizers (AMF and Trichoderma spp.) were compared to unfertilized control over one year. Bacteria and fungi in soil, 162 days from litter deposition, evidenced differentiated clusters for control and both biofertilizers; on the other hand, only fungal composition of litterbags was modified as a consequence of Trichoderma spp. supply; no effect was observed in the bacterial community of litterbags. NIR and TG-DTA analysis evidenced a significant change over time of the chemical composition of litterbags with a faster degradation as a consequence of Trichoderma spp. supply testified by a higher degradation coefficient (1.9) than control (1.6) and AMF (1.7). The supply of biofertilizers partially modified the bacteria community of soil, while Trichoderma spp. Influenced the fungal community of the litter. Moreover, Trichoderma spp. Evidenced a faster and higher degradation of litter than AMF-biofertilizers, laying the foundation for an efficient use in orchard.

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