scholarly journals Plutonium Immobilization Project (PIP) Precursor Material Calcine Temperature

10.2172/9313 ◽  
1999 ◽  
Author(s):  
A.D. Cozzi
Keyword(s):  
Calcine Temperature ◽  
Precursor Material

Structural relationships in the synthesis of cubic boron nitride thin films by ion-assisted deposition

1994 ◽  
Vol 52 ◽  
pp. 638-639
Author(s):  
D. L. Medlin ◽  
T. A. Friedmann ◽  
P. B. Mirkarimi ◽  
M. J. Mills ◽  
K. F. McCarty
Keyword(s):  
Boron Nitride ◽  
Ion Irradiation ◽  
Cubic Boron Nitride ◽  
Film Stress ◽  
Bonded Phases ◽  
Structural Relationships ◽  
Precursor Material ◽  
Pressure Synthesis ◽  
Microstructure Of The Material

The allotropes of boron nitride include two sp2-bonded phases with hexagonal and rhombohedral structures (hBN and rBN) and two sp3-bonded phases with cubic (zincblende) and hexagonal (wurtzitic) structures (cBN and wBN) (Fig. 1). Although cBN is synthesized in bulk form by conversion of hBN at high temperatures and pressures, low-pressure synthesis of cBN as a thin film is more difficult and succeeds only when the growing film is simultaneously irradiated with a high flux of ions. Only sp2-bonded material, which generally has a disordered, turbostratic microstructure (tBN), will form in the absence of ion-irradiation. The mechanistic role of the irradiation is not well understood, but recent work suggests that ion-induced compressive film stress may induce the transformation to cBN.Typically, BN films are deposited at temperatures less than 1000°C, a regime for which the structure of the sp2-bonded precursor material dictates the phase and microstructure of the material that forms from conventional (bulk) high pressure treatment.

scholarly journals High-Quality Green-Emitting Nanodiamonds Fabricated by HPHT Sintering of Polycrystalline Shockwave Diamonds

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Vladimir Yu. Osipov ◽  
Fedor M. Shakhov ◽  
Kirill V. Bogdanov ◽  
Kazuyuki Takai ◽  
Takuya Hayashi ◽  
...  
Keyword(s):  
Polycrystalline Diamond ◽  
Particle Beam ◽  
Production Method ◽  
High Energy ◽  
Nitrogen Vacancy ◽  
High Energy Particle ◽  
Paramagnetic Resonance ◽  
Precursor Material ◽  
Mean Size ◽  
Characteristic Features

Abstract We demonstrate a high-pressure, high-temperature sintering technique to form nitrogen-vacancy-nitrogen centres in nanodiamonds. Polycrystalline diamond nanoparticle precursors, with mean size of 25 nm, are produced by the shock wave from an explosion. These nanoparticles are sintered in the presence of ethanol, at a pressure of 7 GPa and temperature of 1300 °C, to produce substantially larger (3–4 times) diamond crystallites. The recorded spectral properties demonstrate the improved crystalline quality. The types of defects present are also observed to change; the characteristic spectral features of nitrogen-vacancy and silicon-vacancy centres present for the precursor material disappear. Two new characteristic features appear: (1) paramagnetic substitutional nitrogen (P1 centres with spin ½) with an electron paramagnetic resonance characteristic triplet hyperfine structure due to the I = 1 magnetic moment of the nitrogen nuclear spin and (2) the green spectral photoluminescence signature of the nitrogen-vacancy-nitrogen centres. This production method is a strong alternative to conventional high-energy particle beam irradiation. It can be used to easily produce purely green fluorescing nanodiamonds with advantageous properties for optical biolabelling applications.

Effect of Precursor Sol Ageing on Sol-Gel Derived Ruthenium Oxide Thin Films

1999 ◽  
Vol 606 ◽  
Author(s):  
S. Bhaskar ◽  
S. B. Majumder ◽  
P. S. Dobal ◽  
R. S. Katiyar ◽  
A. L. M. Cruz ◽  
...  
Keyword(s):  
Thin Films ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Ruthenium Oxide ◽  
Precursor Solution ◽  
Silicon Substrates ◽  
Solution Deposition ◽  
Precursor Material ◽  
Afm Analysis

AbstractIn the present work we have optimized the process parameters to yield homogeneous, smooth ruthenium oxide (RuO2) thin films on silicon substrates by a solution deposition technique using RuCl3.×.H2O as the precursor material. Films were annealed in a temperature range of 300°C to 700°C, and it was found that RuO2 crystallizes at a temperature as low as 400°C. The crystallinity of the films improves with increased annealing temperature and the resistivity decreases from 4.86µΩ-m (films annealed at 400°C) to 2.94pµΩ (films annealed at 700°C). Ageing of the precursor solution has a pronounced effect on the measured resistivities of RuO2 thin films. It was found that the measured room temperature resistivities increases from 2.94µΩ-m to 45.7µΩ-m when the precursor sol is aged for aged 60 days. AFM analysis on the aged films shows that the grain size and the surface roughness of the annealed films increase with the ageing of the precursor solution. From XPS analysis we have detected the presence of non-transformed RuCl3 in case of films prepared from aged solution. We propose, that solution ageing inhibits the transformation of RuCl3 to RuO2 during the annealing of the films. The deterioration of the conductivity with solution ageing is thought to be related with the chloride contamination in the annealed films.

scholarly journals Isotopic evidence for primordial molecular cloud material in metal-rich carbonaceous chondrites

2016 ◽  
Vol 113 (8) ◽  
pp. 2011-2016 ◽  
Author(s):  
Elishevah M. M. E. Van Kooten ◽  
Daniel Wielandt ◽  
Martin Schiller ◽  
Kazuhide Nagashima ◽  
Aurélien Thomen ◽  
...  
Keyword(s):  
Solar System ◽  
Thermal Processing ◽  
Molecular Cloud ◽  
Decay Product ◽  
Isotopic Signature ◽  
Carbonaceous Chondrites ◽  
Outer Solar System ◽  
Precursor Material ◽  
System Composition ◽  
Cloud Material

The short-lived 26Al radionuclide is thought to have been admixed into the initially 26Al-poor protosolar molecular cloud before or contemporaneously with its collapse. Bulk inner Solar System reservoirs record positively correlated variability in mass-independent 54Cr and 26Mg*, the decay product of 26Al. This correlation is interpreted as reflecting progressive thermal processing of in-falling 26Al-rich molecular cloud material in the inner Solar System. The thermally unprocessed molecular cloud matter reflecting the nucleosynthetic makeup of the molecular cloud before the last addition of stellar-derived 26Al has not been identified yet but may be preserved in planetesimals that accreted in the outer Solar System. We show that metal-rich carbonaceous chondrites and their components have a unique isotopic signature extending from an inner Solar System composition toward a 26Mg*-depleted and 54Cr-enriched component. This composition is consistent with that expected for thermally unprocessed primordial molecular cloud material before its pollution by stellar-derived 26Al. The 26Mg* and 54Cr compositions of bulk metal-rich chondrites require significant amounts (25–50%) of primordial molecular cloud matter in their precursor material. Given that such high fractions of primordial molecular cloud material are expected to survive only in the outer Solar System, we infer that, similarly to cometary bodies, metal-rich carbonaceous chondrites are samples of planetesimals that accreted beyond the orbits of the gas giants. The lack of evidence for this material in other chondrite groups requires isolation from the outer Solar System, possibly by the opening of disk gaps from the early formation of gas giants.

scholarly journals Introduction and Removal of Disinfection Byproducts and Mutagenic Activity by Chemical and Photolytic Treatments

2005 ◽  
Vol 8 (3) ◽  
pp. 387-401 ◽  
Author(s):  
P. Backlund
Keyword(s):  
Carboxylic Acids ◽  
Lake Water ◽  
Mutagenic Activity ◽  
Disinfection Byproducts ◽  
Humic Lake ◽  
River Waters ◽  
Precursor Material ◽  
Strong Mutagen ◽  
Organic Halogens ◽  
Higher Doses

Samples from four different raw water sources were treated with various disinfectants and subjected to chemical analyses and mutagenicity assays. The following disinfectants were used: chlorine (Cl2), chlorine dioxide (ClO2), monochloramine (NH2Cl), ozone (O3), ultraviolet radiation (UV), and combinations of Cl2/ClO2, O3/Cl2, UV/Cl2, and UV/O3/Cl2. The samples were analysed for adsorbable organic halogens (AOX), chloroform (CHCl3), carboxylic acids, volatile organics, chlorite, the strong mutagen 3-chloro-4 (dichloromethyl)-5-hydroxy-2 (5H)-furanone (MX), and mutagenic activity (as detected by the Ames test). Humic lake water which had been treated with the combination UV/Cl2 exhibited a higher level of mutagenicity and higher concentrations of MX and CHCl3 than water treated with Cl2 alone. The same observation was made for the mutagenicity and the CHCl3 concentration in waters preoxidized with low doses of O3 and UV/O3, respectively. When higher doses of these powerful oxidants were used in the pretreatment step, the level of mutagenicity, MX and CHCI3 were lower than in water chlorinated without pretreatment. The combination UV/O3 was found to be more efficient than O3 alone in destroying the precursor material to the mutagenic compounds and chloroform. The higher the proportion of ClO2 in the combined Cl2/ClO2 process, the lower the levels of mutagenicity, MX, CHCl3, and AOX. The production of inorganic chlorite increased with a higher proportion of ClO2. Aldehydes, n-alkanes, and low molecular-weight carboxylic acids were identified as byproducts following UV treatment of humic lake water. The mutagenic activity (per amount of DOC) was approximately similar after chlorination of humic rich surface- and ground waters as after chlorination of waters from the rivers Meuse and Rhine, containing relatively low amounts of humic matter. The precursors to MX were found to be more abundant in the humic waters than in the river waters.

Complex Activation of Coal Gangue to Al Compounds

2011 ◽  
Vol 402 ◽  
pp. 734-737
Author(s):  
Shu Hong Liu ◽  
Xi Jie Lan ◽  
Hong Gao
Keyword(s):  
Particle Size ◽  
Mechanical Activation ◽  
Acid Medium ◽  
Particle Size Analysis ◽  
Coal Gangue ◽  
Size Analysis ◽  
Calcine Temperature ◽  
Processing Effects

The coal gangue was activated by calcine activation, calcine activation + mechanical activation (MA) complex activation. From the results of O2-TPO-MS and Ar-TPR-MS, we can speculate the reactions occurred during the coal gangue calcine activation processing. Effects of calcine temperature, calcine activation + MA complex activation, kinds of acid on the extraction percent of Al were investigated. The results of the extraction percent of Al and particle size analysis show that calcine (400~600 oC) activation and calcine (400~600 oC) + MA complex activation can enhance the extraction percent of Al and decrease the particle size. Much higher extraction percent of Al can be obtained with H2SO4 as acid medium than with HCl as acid medium for the coal gangue activated with the same condition.

Studies on the Ovarian Follicle Cells of Drosophila

1963 ◽  
Vol s3-104 (67) ◽  
pp. 297-320
Author(s):  
R. C. KING ◽  
ELIZABETH A. KOCH
Keyword(s):  
Ovarian Follicle ◽  
Protein A ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Vitelline Membrane ◽  
Membrane Material ◽  
Adjacent Layer ◽  
Membrane Formation ◽  
Precursor Material ◽  
Egg Shell

Studies are described of the ultrastructure of the follicle cells which invest the oocyte of Drosophila melanogaster at the time of vitelline membrane formation. Of particular interest are organelles made up of endoplasmic reticulum organized into a husk of concentric lamellae which surround lipidal droplets. These epithelial bodies are seen only at the time the vitelline membrane is being formed, and it is assumed therefore that the lipidal material of the epithelial body may be utilized somehow in the fabrication of the vitelline membrane. Cytochemical studies have shown this membrane to contain at least 5 classes of compounds; a protein, two lipids (which may be distinguished by differences in their resistance to extraction by various solvents), and 2 polysaccharides (1 neutral and 1 acidic). Studies were made of vitelline membrane formation in the ovaries of flies homozygous for either of 2 recessive, female-sterile genes (tiny and female sterile). In the case of the ty mutation vitelline membrane material is sometimes secreted between follicle and nurse cells, while in the mutant fes vitelline membrane is observed in rare instances to be secreted between follicle cells and an adjacent layer of tumour cells. In the latter case the vitelline membrane shows altered cytochemical properties. The fact that vitelline membrane can be secreted by follicle cells not adjacent to an oocyte demonstrates that it is the follicle cell rather than the oocyte that plays the major role in the secretion of the precursor material of the vitelline membrane. Subsequently the follicle cells secrete the egg-shell, or chorion, which is subdivided into a dense, compartmented, inner endochorion, and a pale, outer exochorion. A description is given of the ultrastructure of the follicle cells during the secretion of the endochorion and the exochorion. The endochorion contains a protein, a polysaccharide, and a lipid, all of which may be distinguished cytochemically from the vitelline membrane compounds. The exochorion contains large amounts of acidic mucopolysaccharides. Specialized follicle cells form the micropylar apparatus and the chorionic appendages. The formation of the chorion and chorionic appendages is discussed in the light of information gained from abnormalities of the chorions and chorionic appendages seen in ty and fs 2.1 oocytes. Subsequent to the time the egg leaves the ovariole a layer of waterproofing wax is secreted between the vitelline membrane and the chorion.

Observations on the Fine Structure and Development of the Spindle at Mitosis and Meiosis in a Marine Centric Diatom (Lithodesmium Undulatum)

1970 ◽  
Vol 7 (2) ◽  
pp. 407-443
Author(s):  
IRENE MANTON ◽  
K. KOWALLIK ◽  
H. A. VON STOSCH
Keyword(s):  
Centric Diatom ◽  
Serial Sections ◽  
Late Prophase ◽  
Haploid Chromosome Number ◽  
Male Gametogenesis ◽  
Common Time ◽  
Precursor Material ◽  
Mitosis And Meiosis ◽  
Meiosis I ◽  
Unusual Shape

The second meiotic division is shown to be of critical importance for interpretation of structures and events already seen at other divisions. The development of flagellar bases at interkinesis is demonstrated in relation to precursor material seen to accumulate near each pole at meiosis I. The name ‘paracentrosome’ is suggested for this material, which is used up in forming the flagellar bases and spindle precursor. The spindle at late prophase, metaphase and telophase II is shown to resemble those of other divisions except that it is consistently smaller; this fact is numerically demonstrated from serial sections of metaphase II cells. The greatly reduced size and unusual shape of the polar plates present in addition to flagellar bases at metaphase II suggest that these are in a sense equivalent structures with a mutually competitive relation to the paracentrosome. Preliminary observations with the light microscope on the relatively large nuclei of oogonia during meiosis I have shown that the haploid chromosome number is not less than 19 nor more than 23 and that chromatid separation in relation to the kinetochores at anaphase I is normal; the bearing of these findings on interpretation of the spindle is discussed. Comparisons with other organisms are carried out in a preliminary way and the investigation ends with a résumé of the more important externally visible events in male gametogenesis adjusted to a common time scale in the course of one day.

Synthesis, Properties, and Applications of Special Substrates Coated by Titanium Dioxide Nanostructured Thin Films via Sol-Gel Process

2011 ◽  
pp. 246-279
Author(s):  
Hamid Dadvar ◽  
Farhad E. Ghodsi ◽  
Saeed Dadvar
Keyword(s):  
Thin Films ◽  
Titanium Dioxide ◽  
Sol Gel ◽  
Precursor Solution ◽  
Tio2 Thin Films ◽  
Simple Method ◽  
Nanostructured Thin Films ◽  
Precursor Material ◽  
Synthesis Properties ◽  
Antibacterial Surfaces

In this chapter, the sol-gel made titanium dioxide nanostructured thin films deposited on special substrates such as glasses, mica, steels, textiles, fibers, and other organic/inorganic substrates were reviewed. Through this review, several distinctive properties such as optical, electrical, photocatalytic, morphological, and mechanical properties of TiO2 nanostructured thin films were described. Also, a wide range of practical application of TiO2 nanostructured thin films such as dye-sensitised solar cells, optical coatings, humidity and gas sensors, selfcleaning, dielectric, and antibacterial surfaces were discussed in details. Dip and spin coating techniques were demonstrated as suitable methods for deposition of thin films. It has been shown that properties of such films can be affected by type of coating technique, stabilizer, precursor material, solvents, pH and viscosity of precursor solution, aging, and etc. Finally, Successive Interference Fringes Method (SIFM) was presented as a simple method for the determination of optical constants and thickness of TiO2 thin films from single transmission measurements.

scholarly journals A comparative study on the effect of different activating solutions and formulations on the early stage geopolymerization process

2020 ◽  
Vol 322 ◽  
pp. 01039
Author(s):  
Lais Alves ◽  
Nordine Leklou ◽  
Silvio de Barros
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Early Stage ◽  
Construction Material ◽  
Potassium Hydroxide Solution ◽  
Mechanical And Thermal Properties ◽  
Liquid Ratio ◽  
Promising Alternative ◽  
Precursor Material ◽  
Activating Solution

Concrete is a major construction material that produces high levels of carbon dioxide in its manufacturing process. Hence the construction sector is responsible for relevant environmental impacts. This justifies the need to find materials as green and ecological alternatives to common Portland cement. Geopolymers represent the most promising alternative due to its proven durability, mechanical and thermal properties. This study investigates the effects of solid-to-liquid and alkali activator ratios on the synthesis of slag-based pure geopolymer and their relation to the geopolymerization process. Two activating solutions were used: a) a mixture of sodium hydroxide, sodium silicate, and water; and b) a mixture of potassium hydroxide solution, potassium silicate, and water. As precursor material, ground blast furnace slag was used. Precursors and activators were mixed with solid-to-liquid ratios in range of 1.5 to 2.2. In the first stage of the study, the mechanical properties were evaluated for each activating solution. In the following stage, different formulations, with variations in the water percentage and solid-to-liquid ratio were tested for mechanical properties and SEM observations. Test results indicate that the resulting geopolymer has the potential for high compressive strength and is directly affected by the composition of the activating solution. It can also be observed that compressive strength was affected by solid-to-liquid ratio and % of water added to the mixture, and strength increased with ageing day.

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