scholarly journals Towards a morphology diagram for terrestrial carbonates: evaluating the impact of carbonate supersaturation and alginic acid in calcite precipitate morphology

2021 ◽  
Author(s):  
Ramon Mercedes-Martín ◽  
Mike Rogerson ◽  
Tim Prior ◽  
Alexander Brasier ◽  
John Reijmer ◽  
...  
Keyword(s):  
Alginic Acid ◽  
Precipitate Morphology ◽  
The Impact

Towards a morphology diagram for terrestrial carbonates: evaluating the impact of carbonate supersaturation and alginic acid in calcite precipitate morphology

2021 ◽  
Author(s):  
Ramon Mercedes-Martín ◽  
Mike Rogerson ◽  
Tim J. Prior ◽  
Alexander T. Brasier ◽  
John J.G. Reijmer ◽  
...  
Keyword(s):  
Alginic Acid ◽  
Precipitate Morphology ◽  
The Impact

scholarly journals Copper(II)-mediated thermolysis of alginates: a model kinetic study on the influence of metal ions in the thermochemical processing of macroalgae

2013 ◽  
Vol 3 (1) ◽  
pp. 20120046 ◽  
Author(s):  
J. S. Rowbotham ◽  
P. W. Dyer ◽  
H. C. Greenwell ◽  
D. Selby ◽  
M. K. Theodorou
Keyword(s):  
Sodium Alginate ◽  
Alginic Acid ◽  
Metal Species ◽  
Thermochemical Conversion ◽  
Infrared Spectroscopic Study ◽  
Model Compounds ◽  
Brown Macroalgae ◽  
Metal Contents ◽  
Thermochemical Processing ◽  
The Impact

Thermochemical processing methods such as pyrolysis are of growing interest as a means of converting biomass into fuels and commodity chemicals in a sustainable manner. Macroalgae, or seaweed, represent a novel class of feedstock for pyrolysis that, owing to the nature of the environments in which they grow coupled with their biochemistry, naturally possess high metal contents. Although the impact of metals upon the pyrolysis of terrestrial biomass is well documented, their influence on the thermochemical conversion of marine-derived feeds is largely unknown. Furthermore, these effects are inherently difficult to study, owing to the heterogeneous character of natural seaweed samples. The work described in this paper uses copper(II) alginate, together with alginic acid and sodium alginate as model compounds for exploring the effects of metals upon macroalgae thermolysis. A thermogravimetric analysis–Fourier transform infrared spectroscopic study revealed that, unusually, Cu 2+ ions promote the onset of pyrolysis in the alginate polymer, with copper(II) alginate initiating rapid devolatilization at 143°C, 14°C lower than alginic acid and 61°C below the equivalent point for sodium alginate. Moreover, this effect was mirrored in a sample of wild Laminaria digitata that had been doped with Cu 2+ ions prior to pyrolysis, thus validating the use of alginates as model compounds with which to study the thermolysis of macroalgae. These observations indicate the varying impact of different metal species on thermochemical behaviour of seaweeds and offer an insight into the pyrolysis of brown macroalgae used in phytoremediation of metal-containing waste streams.

scholarly journals Selective adsorption behavior of Cd2+ imprinted acrylamide-crosslinked-poly(alginic acid) magnetic polymers: fabrication, characterization, adsorption performance and mechanism

2020 ◽  
Author(s):  
Zuyu Li ◽  
Shuangzhen Guo ◽  
Da Li ◽  
Lihua Zang
Keyword(s):  
Metal Ions ◽  
Adsorption Capacity ◽  
Alginic Acid ◽  
Selective Adsorption ◽  
Physical Adsorption ◽  
Maximum Adsorption Capacity ◽  
Magnetic Adsorbent ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
The Impact

Abstract Poly(acrylamide) grafted and glutaraldehyde-crosslinked alginic acid nano-magnetic adsorbent (AAMA) was prepared by selecting Cd2+ as a template ion. Scanning electron microscope (SEM), Thermo-gravimetric analyzer (TGA), Vibrating sample magnetometer (VSM) and Infrared Spectroscopy (IR)were used to characterize the morphology and structure of AAMA. The adsorption of AAMA for different metal ions was compared and the impact of various factors for adsorption of Cd2+ was systematically investigated. These results suggested that the AAMA was the aggregates of Fe3O4 nanoparticles with a diameter of about 50–100 nm. and had selectivity for Cd2+ adsorption. The maximum adsorption capacity for Cd2+ is 175 mg/g at pH 5.0 and 303 K. The experimental data were well described by the Langmuir isotherm model and pseudo-second-order model. The parameters of adsorption thermodynamics concluded that the adsorption progress is spontaneous and endothermic in nature. The parameters of adsorption activation energy suggested that there is physical adsorption and chemisorption on the adsorption of metal ions. AAMA could be regenerated by EDTA and still keep 71% adsorption capacity in the fifth consecutive adsorption-regeneration cycle. Therefore, AAMA would be useful as a selective and high adsorption capacity nano-magnetic adsorbent in the removal of Cd2+ from wastewater.

Analysis of the microstructure and properties of T92 steel after long-term service

2018 ◽  
Vol 1 (93) ◽  
pp. 5-11
Author(s):  
A. Merda ◽  
K Klimaszewska ◽  
M. Sroka ◽  
P. Wieczorek ◽  
G. Golański
Keyword(s):  
Mechanical Properties ◽  
Hardness Measurement ◽  
Steam Superheater ◽  
Martensitic Steels ◽  
Precipitate Morphology ◽  
Microstructural Investigation ◽  
Microstructure And Mechanical Properties ◽  
Static Tensile ◽  
The Impact

Purpose: The purpose of the investigation was to determine and analyse the changes in the microstructure and mechanical properties of the T92 steel after service in creep conditions of the following parameters: temperature – 575°C, pressure – 28.2 MPa, service time – 41914 hrs. Design/methodology/approach: The tests were performed on the test samples taken from a pipe section of a steam superheater after long-term service. The range of the investigations included: microstructural investigation – the optical and SEM microscopy, the analysis of precipitation – carbide isolates, the investigation of mechanical properties: the Vickers hardness measurement, the impact test and static tensile test. Findings: The performed tests showed a slight degree of exhaustion of the structure of the analysed T92 steel. The relatively small changes in the microstructure of the examined steel were reflected in the still retained high mechanical properties. Research limitations/implications: he analysis of the microstructure of the examined steel using SEM was performed to determine the influence of the service on the processes of changes in the precipitate morphology. Practical implications: The metal science investigation of the sections taken from the elements of the power installations after long-term service is one of the basic elements of building the data base of materials and their joints used in the power industry. The results obtained from the performed research constitute a building block for the degradation characteristics of the microstructure and mechanical properties of martensitic steels of the 9-12%Cr type. Originality/value: The results of investigation and analysis of the metallographic and mechanical properties of martensitic T92 steel after long-term service are presented.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Organic Syntheses During the Impact of a Comet with a Gaseous Planet

1997 ◽  
Vol 161 ◽  
pp. 189-195
Author(s):  
Cesare Guaita ◽  
Roberto Crippa ◽  
Federico Manzini
Keyword(s):  
Polymeric Material ◽  
Molecular Form ◽  
Parent Compound ◽  
Blue Filter ◽  
Organic Syntheses ◽  
The Impact

AbstractA large amount of CO has been detected above many SL9/Jupiter impacts. This gas was never detected before the collision. So, in our opinion, CO was released from a parent compound during the collision. We identify this compound as POM (polyoxymethylene), a formaldehyde (HCHO) polymer that, when suddenly heated, reformes monomeric HCHO. At temperatures higher than 1200°K HCHO cannot exist in molecular form and the most probable result of its decomposition is the formation of CO. At lower temperatures, HCHO can react with NH3 and/or HCN to form high UV-absorbing polymeric material. In our opinion, this kind of material has also to be taken in to account to explain the complex evolution of some SL9 impacts that we observed in CCD images taken with a blue filter.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

Morphology, Distribution and Identification of Micro-Constituents Along Grain Boundaries in Nickel-Base Alloys

1973 ◽  
Vol 31 ◽  
pp. 176-177
Author(s):  
D. E. Fornwalt ◽  
A. R. Geary ◽  
B. H. Kear
Keyword(s):  
Electron Microscope ◽  
Grain Boundaries ◽  
Volume Fraction ◽  
Rupture Life ◽  
Stress Rupture ◽  
High Volume ◽  
Precipitate Morphology ◽  
Stress Rupture Life ◽  
Nickel Base ◽  
Scanning Electron

A systematic study has been made of the effects of various heat treatments on the microstructures of several experimental high volume fraction γ’ precipitation hardened nickel-base alloys, after doping with ∼2 w/o Hf so as to improve the stress rupture life and ductility. The most significant microstructural chan§e brought about by prolonged aging at temperatures in the range 1600°-1900°F was the decoration of grain boundaries with precipitate particles.Precipitation along the grain boundaries was first detected by optical microscopy, but it was necessary to use the scanning electron microscope to reveal the details of the precipitate morphology. Figure 1(a) shows the grain boundary precipitates in relief, after partial dissolution of the surrounding γ + γ’ matrix.

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