Effect of the molar ratio of calcium sulfate over ye'elimite on the reaction of CSA cement/slag blends under an accelerated carbonation condition

2021 ◽  
pp. 103785
Author(s):  
Joonho Seo ◽  
Seonhyeok Kim ◽  
H.N. Yoon ◽  
H.K. Lee
Keyword(s):  
Calcium Sulfate ◽  
Molar Ratio ◽  
Accelerated Carbonation

Study on the Preparation of Calcium Sulfate Whisker by Hydrothermal Method

2012 ◽  
Vol 602-604 ◽  
pp. 1369-1372 ◽  
Author(s):  
Kang Bi Luo ◽  
Hu Ping Li ◽  
Yan Xia Tan
Keyword(s):  
Hydrothermal Method ◽  
Calcium Chloride ◽  
Sodium Sulfate ◽  
Calcium Sulfate ◽  
Sulfate Solution ◽  
Solution Concentration ◽  
Raw Material ◽  
Molar Ratio ◽  
Feed Mode ◽  
Calcium Sulfate Whiskers

This article took the sodium sulfate and calcium chloride as the raw material and prepared calcium sulfate whiskers by hydrothermal method. The experimental results show that the calcium sulfate precursors are prepared by the reverse feed mode in which the sodium sulfate solution drop into the calcium chloride solution under the solution concentration 0.6 mol/L and the molar ratio of Na2SO4 to CaCl2 at 1:1.8. The precursors were placed in pH=6.12 hydrothermal environments and treated in the autoclave at 140 °C for 4 h to obtain the calcium sulfate whiskers having for the ratio of length to diameter at 97.5 and the better morphology.

scholarly journals Quantitative in Situ X-ray Diffraction Analysis of Early Hydration of Belite-Calcium Sulfoaluminate Cement at Various Defined Temperatures

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 297
Author(s):  
Maruša Borštnar ◽  
Christian L. Lengauer ◽  
Sabina Dolenec
Keyword(s):  
Calcium Sulfate ◽  
Elevated Temperatures ◽  
Cement Clinker ◽  
Molar Ratio ◽  
Phase Assemblage ◽  
Early Hydration ◽  
X Ray ◽  
Calcium Sulfoaluminate ◽  
Molar Ratios

The influence of temperature on the early hydration of belite-calcium sulfoaluminate cements with two different calcium sulfate to calcium sulfoaluminate molar ratios was investigated. The phase composition and phase assemblage development of cements prepared using molar ratios of 1 and 2.5 were studied at 25, 40 and 60 °C by in situ X-ray powder diffraction. The Rietveld refinement method was used for quantification. The degree of hydration after 24 h was highest at ambient temperatures, but early hydration was significantly accelerated at elevated temperatures. These differences were more noticeable when we increased the temperature from 25 °C to 40 °C, than it was increased from 40 °C to 60 °C. The amount of calcium sulfate added controls the amount of the precipitated ettringite, namely, the amount of ettringite increased in the cement with a higher molar ratio. The results showed that temperature also affects full width at half maximum of ettringite peaks, which indicates a decrease in crystallite size of ettringite at elevated temperatures due to faster precipitation of ettringite. When using a calcium sulfate to calcium sulfoaluminate molar ratio of 1, higher d-values of ettringite peaks were observed at elevated temperatures, suggesting that more ions were released from the cement clinker at elevated temperatures, allowing a higher ion uptake in the ettringite structure. At a molar ratio of 2.5, less clinker is available in the cement, therefore these differences were not observed.

scholarly journals RESEARCH OF THE POSSIBILITY OF REDUCING THE CIRCULATION OF SULFUR OXIDE IN THE PRODUCTION OF WHITE CEMENT

2021 ◽  
Vol 6 (7) ◽  
pp. 89-98
Author(s):  
A. Novosyolov ◽  
I. Olianina ◽  
I. Novoselova ◽  
Y. Vasina ◽  
Y. Ershova ◽  
...  
Keyword(s):  
Calcium Sulfate ◽  
Sodium Oxide ◽  
Molar Ratio ◽  
Oxide Content ◽  
Sulfur Oxide ◽  
White Cement ◽  
Alkali Oxides ◽  
Potassium Oxides ◽  
Alkaline Oxides

The article discusses the possibility of reducing the circulation of sulfur oxide in the production of white cement by introducing alkaline potassium oxides K2O and sodium Na2O. A decrease in the circulation of sulfur oxide SO3 is achieved by increasing its yield in the clinker by transferring SO3 from a more sublimated compound of calcium sulfate CaSO4 to less sublimated potassium sulfates K2SO4 and sodium Na2SO4. Potassium and sodium oxides are introduced in the composition of carbonates and feldspar. The amount of introduced alkali oxides is controlled by the molar ratio A/S between sulfur oxide SO3 and alkaline oxides K2O and Na2O. It is shown that with the same molar ratio between sulfur oxide and alkaline oxides, the amount of SO3 removed with clinker depends on the ratio between potassium and sodium oxides. The higher the sodium oxide content, the more sulfur oxide comes out with the clinker and less remains to circulate in the kiln. The sublimation of sulfur oxide decreases from 70.5% - without the introduction of alkaline oxides, to 38,5 % at the maximum A/S ratio with the addition of potassium and sodium oxides in a ratio of 80:20 %. When potassium and sodium oxides are added in a ratio of 20:80%, the sublimation of sulfur oxide is reduced to 7,7 % at the same A/S ratio.

Effects of sterilization modes on the mechanical strengths of plaster of paris implants

1989 ◽  
Vol 47 ◽  
pp. 890-891
Author(s):  
K. Cowden ◽  
B. Giammara ◽  
T. Devine ◽  
J. Hanker
Keyword(s):  
Gamma Radiation ◽  
Calcium Sulfate ◽  
Significant Loss ◽  
Potassium Sulfate ◽  
Limiting Factors ◽  
Radiation Sterilization ◽  
Plaster Of Paris ◽  
Hardness Tester ◽  
Dry Heat ◽  
Calcium Sulfate Hemihydrate

Plaster of Paris (calcium sulfate hemihydrate, CaSO4. ½ H2O) has been used as a biomedical implant material since 1892. One of the primary limiting factors of these implants is their mechanical properties. These materials have low compressive and tensile strengths when compared to normal bone. These are important limiting factors where large biomechanical forces exist. Previous work has suggested that sterilization techniques could affect the implant’s strength. A study of plaster of Paris implant mechanical and physical properties to find optimum sterilization techniques therefore, could lead to a significant increase in their application and promise for future use as hard tissue prosthetic materials.USG Medical Grade Calcium Sulfate Hemihydrate Types A, A-1 and B, were sterilized by dry heat and by gamma radiation. Types A and B were additionally sterilized with and without the setting agent potassium sulfate (K2SO4). The plaster mixtures were then moistened with a minimum amount of water and formed into disks (.339 in. diameter x .053 in. deep) in polyethylene molds with a microspatula. After drying, the disks were fractured with a Stokes Hardness Tester. The compressive strengths of the disks were obtained directly from the hardness tester. Values for the maximum tensile strengths σo were then calculated: where (P = applied compression, D = disk diameter, and t = disk thickness). Plaster disks (types A and B) that contained no setting agent showed a significant loss in strength with either dry heat or gamma radiation sterilization. Those that contained potassium sulfate (K2SO4) did not show a significant loss in strength with either sterilization technique. In all comparisons (with and without K2SO4 and with either dry heat or gamma radiation sterilization) the type B plaster had higher compressive and tensile strengths than that of the type A plaster. The type A-1 plaster however, which is specially modified for accelerated setting, was comparable to that of type B with K2SO4 in both compressive and tensile strength (Table 1).

Lipid Polymorphism and Virus-Membrane Fusion as Observed in Vitrified Thin Films by Cryo-Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 492-493
Author(s):  
P.M. Frederik ◽  
K.N.J. Burger ◽  
M.C.A. Stuart ◽  
A.J. Verkleij
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Membrane Fusion ◽  
Film Formation ◽  
Molar Ratio ◽  
Influenza B ◽  
Complex Structures ◽  
Type Ii ◽  
Suspended Material ◽  
Cryo Electron Microscopy

Cellular membranes are often composed of phospholipid mixtures in which one or more components have a tendency to adopt a type II non-bilayer lipid structure such as the inverted hexagonal (H||) phase. The formation of a type II non-bilayer intermediate, the inverted lipid micel is proposed as the initial step in membrane fusion (Verkleij 1984, Siegel, 1986). In the various forms of cellular transport mediated by carrier vesicles (e.g. exocytosis, endocytosis) the regulation of membrane fusion, and hence of inverted lipid micel formation, is of vital importance.We studied the phase behaviour of simple and complex lipid mixtures by cryo-electron microscopy to gain more insight in the ultrastructure of different lipid phases (e.g. Pβ’, Lα, H||) and in the complex membrane structures arising after Lα < - > H|| phase changes (e.g. isotropic, cubic). To prepare hydrated thin films a 700 mesh hexagonal grid (without supporting film) was dipped into and withdrawn from a liposome suspension. The excess fluid was blotted against filter paper and the thin films that form between the bars of the specimen grid were immediately (within 1 second) vitrified by plunging of the carrier grids into ethane cooled to its melting point by liquid nitrogen (Dubochet et al., 1982). Surface active molecules such as phospholipids play an important role in the formation and thinning of these aqueous thin films (Frederik et al., 1989). The formation of two interfacial layers at the air-water interfaces requires transport of surface molecules from the suspension as well as the orientation of these molecules at the interfaces. During the spontaneous thinning of the film the interfaces approach each other, initially driven by capillary forces later by Van der Waals attraction. The process of thinning results in the sorting by size of the suspended material and is also accompanied by a loss of water from the thinner parts of the film. This loss of water may result in the concentration and eventually in partial dehydration of suspended material even if thin films are vitrified within 1 sec after their formation. Film formation and vitrification were initiated at temperatures between 20-60°C by placing die equipment in an incubator provided widi port holes for the necessary manipulations. Unilamellar vesicles were made from dipalmitoyl phosphatidyl choline (DPPC) by an extrusion method and showed a smooth (Lα) or a rippled (PB’.) structure depending on the temperature of the suspensions and the temperature of film formation (50°C resp. 39°C) prior to vitrification. The thermotropic phases of hydrated phospholipids are thus faithfully preserved in vitrified thin films (fig. a,b). Complex structures arose when mixtures of dioleoylphosphatidylethanol-amine (DOPE), dioleoylphosphatidylcholine (DOPC) and cholesterol (molar ratio 3/1/2) are heated and used for thin film formation. The tendency of DOPE to adopt the H|| phase is responsible for the formation of complex structures in this lipid mixture. Isotropic and cubic areas (fig. c,d) having a bilayer structure are found in coexistence with H|| cylinders (fig. e). The formation of interlamellar attachments (ILA’s) as observed in isotropic and cubic structures is also thought to be of importance in biological fusion events. Therefore the study of the fusion activity of influenza B virus with liposomes (DOPE/DOPC/cholesterol/ganglioside in a molar ratio 1/1/2/0.2) was initiated. At neutral pH only adsorption of virus to liposomes was observed whereas 2 minutes after a drop in pH (7.4 - > 5.4) fusion between virus and liposome membranes was demonstrated (fig. f). The micrographs illustrate the exciting potential of cryo-electron microscopy to study lipid-lipid and lipid-protein interactions in hydrated specimens.

A New Method for Plasminogen Standardization

1968 ◽  
Vol 20 (03/04) ◽  
pp. 548-554
Author(s):  
J Gajewski ◽  
G Markus
Keyword(s):  
Proteolytic Activity ◽  
Specific Activity ◽  
Molar Ratio ◽  
Sharp Transition ◽  
Equivalence Point ◽  
Constant Amount ◽  
Residual Level ◽  
Activity Measurements ◽  
Complete Saturation ◽  
Human Plasminogen

SummaryA method for the standardization of human plasminogen is proposed, based on the stoichiometric interaction between plasminogen and streptokinase, resulting in inhibition of proteolytic activity. Activation of a constant amount of plasminogen with increasing amounts of streptokinase yields linearly decreasing activities, as a function of streptokinase, with a sharp transition to a constant residual level. The point of transition corresponds to complete saturation of plasmin with streptokinase in a 1:1 molar ratio, and is therefore a measure of the amount of plasminogen present initially, in terms of streptokinase equivalents. The equivalence point is independent of the kind of protein substrate used, buffer, pH, length of digestion and, within limits, temperature. The method, therefore, is not subject to the variations commonly encountered in the usual determination based on specific activity measurements.

Identification of acid-insoluble filter-plugging compounds and optimal acid-washing procedures for tubular backpulse pressure filters

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 17-23
Author(s):  
KEVIN TAYLOR ◽  
RICH ADDERLY ◽  
GAVIN BAXTER
Keyword(s):  
Calcium Sulfate ◽  
Membrane Filter ◽  
Sulfamic Acid ◽  
Xrd Analysis ◽  
Metal Sulfides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gypsum Formation ◽  
Acid Washing ◽  
Hydrolysis Of

Over time, performance of tubular backpulse pressure filters in kraft mills deteriorates, even with regular acid washing. Unscheduled filter replacement due to filter plugging results in significant costs and may result in mill downtime. We identified acid-insoluble filter-plugging materials by scanning electron microscope/energy-dispersion X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis in both polypropylene and Gore-Tex™ membrane filter socks. The major filter-plugging components were calcium sulfate (gypsum), calcium phosphate (hydroxylapatite), aluminosilicate clays, metal sulfides, and carbon. We carried out detailed sample analysis of both the standard acid-washing procedure and a modified procedure. Filter plugging by gypsum and metal sulfides appeared to occur because of the acid-washing procedure. Gypsum formation on the filter resulted from significant hydrolysis of sulfamic acid solution at temperatures greater than 130°F. Modification of the acid-washing procedure greatly reduced the amount of gypsum and addition of a surfactant to the acid reduced wash time and mobilized some of the carbon from the filter. With surfactant, acid washing was 95% complete after 40 min.

Fungicidal and Bactericidal Activity of the Alkyl-Substituted Guanidine-Containing Oligomers

2020 ◽  
Vol 82 (6) ◽  
pp. 54-63
Author(s):  
M.Ya. Vortman ◽  
◽  
Yu.B. Pysmenna ◽  
A.I. Chuenko ◽  
D.R. Abdulina ◽  
...  
Keyword(s):  
Heterotrophic Bacteria ◽  
Trichoderma Viride ◽  
Rhodococcus Erythropolis ◽  
Biological Action ◽  
Molar Ratio ◽  
Diffusion Method ◽  
Klebsiella Pneumonia ◽  
Alkyl Bromides ◽  
Base Form ◽  
Two Stages

Biocides are widely used in medicine and various industries to protect against a number of harmful microorganisms. Organic quaternary ammonium and guanidine-containing compounds, the biological action of which is based on membrane-toxic properties, are used as bactericidal preparations. The aim of this work was to study the bactericidal and fungicidal activities of the synthesized oligomeric alkylsubstituted guanidinium bromides with different radicals -C3H7, -C7H15, -C10H21, against different isolates of heterotrophic bacteria and microscopic fungi. Methods. The synthesis of alkyl-substituted guanidiniumcontaining oligomers was performed in two stages. In the first stage, alkyl-substituted guanidine was obtained by the reaction of guanidine, previously converted by alkali from the salt form to the base form by the base and alkyl bromides (Alk=-C3H7 (propyl), -C7H15 (heptyl), -C10H21 (decyl)) in methanol at a temperature of 50°C and a molar ratio of 1:1. The second carried out the reaction between aromatic oligoepoxide DER-331 and alkyl-substituted guanidine in methanol at a temperature of 50°C for 2–3 hours and a molar ratio of 1:2. Bacteria were grown on meat-peptone agar for 48 hours at a temperature of 28±2°С. Test cultures of micromycetes were cultured on agar beer wort (6°B), incubated for 14 days in a thermostat at a temperature of 28±2°C. Antimicrobial activity of newly synthesized alkyl-substituted guanidinium-containing oligomers was determined by standard disco-diffusion method (method of disks on agar) and fungicidal activity was determined by the method of holes in agar. Results. Oligomeric alkylsubstituted guanidinium bromides with different radicals composed -C3H7, -C7H15, -C10H21- synthesized by the reaction of guanidine alkyl bromides with aromatic oligoepoxydes. It was found that alkyl-substituted guanidinium-containing oligomers at a concentration of 1–3% inhibited the growth of Escherichia coli 475, Pseudomonas aeruginosa 465, Klebsiella pneumonia 479, Pseudomonas pseudoalcaligenes 109, Staphylococcus aureus 451, E. faecalis 422, Rhodococcus erythropolis 102, Bacillus subtilis 138 and most of the studied micromycetes – Aureobasidium pullulans F-41430, Paecilomyces variotii F-41432, Penicillium funiculosum F-41435, Penicillium ochrochloron F-41431, Scopulariopsis brevicaulis F-41434, Trichoderma viride F-41437, Candida albicans F-41441, Aspergillus flavus F-41442, Aspergillus niger F-41448, Penicillium sp. F-41447. Conclusions. Antimicrobial and fungicidal properties significantly depend on the length of the alkyl radical, with increasing of its length the diameter of the zone of bacterial and micromycetes growth retardation increases.10.15407/microbiolj82.06.054

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