scholarly journals Sintering Optimisation and Recovery of Aluminum and Sodium from Greek Bauxite Residue

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 571 ◽  
Author(s):  
Tam ◽  
Panias ◽  
Vassiliadou
Keyword(s):  
Bauxite Residue ◽  
Calcium Content ◽  
Sodium Aluminate ◽  
Product Formation ◽  
Inert Atmosphere ◽  
Metallurgical Coke ◽  
Aluminum Silicate ◽  
Aluminum Recovery ◽  
High Calcium ◽  
Alumina Addition

Bauxite residue is treated for the recovery of aluminum and sodium by sintering with the addition of soda, metallurgical coke and other reagents such as CaO, MgO and BaO. A thorough thermodynamic analysis using Factsage 7.0™ software was completed together with XRD mineralogy of sinters with different fluxes and reagents additions. Through both thermodynamic interpretation and mineralogical confirmations, it was observed that the type of desilication product in bauxite residue influences the total aluminum recovery through the sintering process and formation of sodium aluminum silicate exists in equilibrium with sodium aluminate, unless silica is consumed by additives (such as CaO, MgO, BaO etc.) forming other more thermodynamically favorable species and liberating alumina. Addition of barium oxide improves the aluminum and sodium recovery to 75% and 94% respectively. Complex sinter product formation that are triggered due to high calcium content in the Greek bauxite residue reduces aluminum recovery efficiency. Optimised and feasible recovery of aluminum and sodium for Greek bauxite residue was proved to be 70% and 85% respectively, when sintered with 50% excess stoichiometric soda. It was observed that stoichiometric carbon addition in inert atmosphere only assisted recovery up to 75% of aluminum and 83% of sodium, though there are benefits gained from pre-reducing iron from hematite for downstream recovery.

Variasi Penambahan Tepung Daun Kelor (Moringa Oleifera Lam.) pada Pembuatan Flakes Ditinjau dari Sifat Fisik, Sifat Organoleptik dan Kadar Kalsium

2017 ◽  
Vol 19 (1) ◽  
pp. 31-35
Author(s):  
Frieda Rosita Majid ◽  
Nur Hidayat ◽  
Waluyo Waluyo
Keyword(s):  
Physical Characteristic ◽  
Nutritional Value ◽  
Calcium Content ◽  
Organoleptic Characteristics ◽  
High Calcium ◽  
Randomized Experimental Design ◽  
Leaf Powder ◽  
The Difference ◽  
The Tropics ◽  
Moringa Oleifera Lam

Background:Moringa (Moringaoleifera Lam.) Is a plant of high nutritional value, grows scattered in the tropics and sub-tropics, but utilization is still low. Each section has its benefits Moringa one part is the Moringa leaves contain a high calcium. In 100 grams of material, fresh Moringa leaves contain as much as 440 mg of calcium in the form of flour whereas if it contains as much as 2,003 mg of calcium. One of its use in the manufacture of flakes added. Objective: Know the difference physical harateristi, organoleptic characteristic and calcium levels in flakes variations addition of Moringa leaf powder. Methods: The study is a randomized experimental design with simple, includes four kinds of treatments, two replications with two experimental units. Observations of physical characteristic were analyzed by descriptive, the organoleptic characteristic of data analysis using statistical test Kruskal-Wallis continued Mann-Whitney and methods of test calcium content using permanganometri then the data were analyzed descriptive. Results: The physical characteristics of flakes greenish-yellow, slightly fragrant aroma typical of flakes, rather unpleasant taste typical of Moringa leaves and a slightly crunchy texture. Organoleptic characteristics the color of flakes with moringa leaf powder 5%, the aroma of the flakes without addition moringa leaf powder, the flavour of flakes with additions moringa leaf powder 5% and the texture of flakes with additions moringa leaf powder 7,5% most prefered panelist and high levels calcium of flakes with additions 10% moringa leaf powder. Conclusion: There is a difference variations addition of moringa leaf powder on physical, organoleptic characteristic (color) and the level of calcium flakes.Flakes with the addition of 5% moringa leaf powder is the most prefered panelist.   Keywords:Moringa Leaf Flour, Flakes, Physical characteristic, organoleptic, Calcium

Variants of the Circle of Willis as seen on magnetic resonance angiography and carotid siphon calcifications in community-dwelling older adults

2021 ◽  
pp. 197140092110428
Author(s):  
Oscar H Del Brutto ◽  
Bettsy Y. Recalde ◽  
Robertino M Mera
Keyword(s):  
Older Adults ◽  
Magnetic Resonance ◽  
Calcium Content ◽  
Circle Of Willis ◽  
Community Dwelling ◽  
Anatomical Variants ◽  
Study Results ◽  
High Calcium ◽  
Independent Association ◽  
Community Dwelling Older Adults

Background and purpose Information on the association between anatomical variants of the Circle of Willis (CoW) and intracranial atherosclerotic disease (ICAD) is limited and results are controversial. In this population-based study, we aimed to assess whether an incomplete CoW is associated with high calcium content in carotid siphons (a reliable biomarker of ICAD) in community-dwelling older adults of Amerindian ancestry. Methods Individuals aged ≥60 years enrolled in the Three Villages Study received a head computed tomography (CT) and magnetic resonance angiogram (MRA) of intracranial vessels. The CoW was classified in complete or incomplete according to the presence or absence of one A1 segment of the anterior cerebral artery or one or both P1 segments of posterior cerebral arteries. Calcium content in carotid siphons was rated as low or high. A multivariate logistic model was fitted to assess the independent association between incompleteness of the CoW and high calcium content in carotid siphons, after adjusting for demographics and cardiovascular risk factors. Results A total of 581 individuals were enrolled (mean age: 71 ± 8.4 years; 57% women). MRA revealed an incomplete CoW in 227 (39%) individuals, and high-resolution CT disclosed high calcium content in carotid siphons in 185 (32%). A risk factor logistic regression model showed no independent association between incompleteness of the CoW and high calcium content in carotid siphons (odds ratio: 0.91; 95% confidence interval: 0.62–1.34; p = 0.631). Conclusion Study results disclosed no association between anatomical variants of the CoW and the presence of high calcium content in carotid siphons.

Extraction and Atomic Absorption Analysis of Lead in Plant and Animal Products

1969 ◽  
Vol 52 (4) ◽  
pp. 708-714 ◽  
Author(s):  
William L Hoover ◽  
John C Reagor ◽  
Julianne C Garner
Keyword(s):  
Atomic Absorption ◽  
Ammonium Carbonate ◽  
Calcium Content ◽  
Atomic Absorption Spectrophotometry ◽  
Animal Tissue ◽  
Good Recovery ◽  
Animal Products ◽  
Absorption Spectrophotometry ◽  
Strontium Sulfate ◽  
High Calcium

Abstract Samples of plant or animal tissue are digested in a mixture of HNO3, H2SO4, and HClO4. Lead released in the digestion is entrained with strontium sulfate. The sulfate precipitate is separated from the digest and then converted to the carbonate by agitation with ammonium carbonate solution. The carbonate precipitate is dissolved in 1N HNO3, and lead is determined by atomic absorption spectrophotometry. Good recovery of lead (100 ± 3%) was observed except in samples with high calcium content (> 1%). For the latter samples, good recoveries were obtained after separation of the calcium from the digested samples. Moderate quantities of the following elements do not interfere: Al, Fe, P, Sn, Ca, Bi, and Tl. Most elements are soluble as sulfates and, hence, do not interfere. The procedure is rugged. Dry samples containing from 0.5 ppm to 1% lead can be routinely analyzed.

scholarly journals ANÁLISE DE CÁLCIO EM DIFERENTES TIPOS DE BEBIDAS

2002 ◽  
Vol 3 (2) ◽  
Author(s):  
L. BATTESTIN ◽  
R. M. B. TACLA ◽  
E. B. TIBONI ◽  
R. J. S. FREITAS ◽  
S. C STERTZ
Keyword(s):  
Soy Protein ◽  
Calcium Content ◽  
Black Tea ◽  
Hot Water ◽  
Soy Milk ◽  
Freeze Dried ◽  
High Calcium ◽  
Two Samples ◽  
Powder Milk ◽  
Isolated Soy Protein

Foram analisadas infusos de duas amostras de chá preto, uma amostra de orange pekoe tipo Assam, duas amostras de chá mate tostado, quatro amostras de erva-mate e uma amostra de café liofilizado, dissoluções à quente de uma amostra de leite em pó desnatado, uma amostra de leite em pó integral e uma amostra de alimento com proteína isolada de soja instantâneo. Estas amostras foram adquiridas em supermercados da Região Metropolitana de Curitiba; com a finalidade de verificar e comparar os teores de cálcio desses diferentes tipos de bebidas. Nas determinações foi utilizada metodologia oficial e todas as análises em triplicata. Os teores de cálcio obtidos foram analisados estatisticamente: as amostras de chá preto apresentaram o menor teor de cálcio que variou de 16,94 mg/100 mL até 24,84 mg/100 mL. As amostras de chámate tostado mostraram valores mais elevados, sendo que uma delas acusou 78,39 mg/100 mL, equivalendo aomesmo teor de cálcio de umleite empó. Quanto às amostras de erva-mate, amaioria comparase à quantidade de cálcio dos leites empó e do alimento comproteína isolada de soja instantâneo, onde uma destacou-se significativamente das demais com valor de 171,55 mg/100 mL, seguida apenas da amostra de café liofilizado que apresentou 141,68 mg/100 mL. CALCIUM ANALYSIS IN DIFFERENT DRINKS Abstract Two samples of black tea, a sample of orange pekoe variety Assam, two samples of toasted tea, four varieties of erva-mate, a freeze dried coffee sample were prepared by hot infusion, samples of skimmed powder milk and powder wholemilk and one instant isolated soy protein sample were prepared in hot water. These samples were purchased in markets in Curitiba to identify and analyze calcium content in comparison with Official methodologies were used and for all determinations three analyses were done. Black tea samples resulted minor calcium content (16.94 to 24.84 mg/ 100 mL). Toasted tea resulted major calcium amount with 78.39 mg/100 mL, similar to calcium amount of powder and soy milk. Erva-mate samples are comparable to calcium content in powder milk. Freeze dried coffee presented high calcium amount (141.68 mg/100 mL).

scholarly journals Adaptation of plants to high-calcium content kart regions: possible involvement of symbiotic microorganisms and underlying mechanisms

2020 ◽  
Vol 80 (1) ◽  
pp. 209-214
Author(s):  
F. Li ◽  
X. He ◽  
M. Tang ◽  
X. Tang ◽  
J. Liu ◽  
...  
Keyword(s):  
Host Plants ◽  
Molecular Mechanisms ◽  
Calcium Content ◽  
Ecological Functions ◽  
Rhizosphere Microorganisms ◽  
High Calcium ◽  
Volatile Organic ◽  
Underlying Mechanisms ◽  
Host Genes ◽  
Adverse Environments

Abstract Rhizosphere microorganisms and endophytes can help their hosts absorb nutrients and regulate the levels of plant hormones. Moreover, they can modulate the expressions of host genes, assist hosts in eliminating reactive oxygen species (ROS) and secreting volatile organic compounds. Therefore, rhizosphere microorganisms and endophytes are considered as determinant factors driving processes involved in the growth of host plants. However, the physiological and ecological functions, as well as the molecular mechanism underlying the behavior of rhizosphere microorganisms and endophytes in their role in the adaptive capacity of host plants in the karstic high-calcium environment have not been systematically studied. This review summarizes the physiological and molecular mechanisms of rhizosphere microorganisms and endophytes which help host plants to adapt to various kinds of adverse environments. The adaptive capacities of plants growing in adverse environments, partly, or totally, depends on microorganisms co-existing with the host plants.

Kinetic Calculations for the Calcination Reaction of Limestone Modified by Alkaline Industrial Wastes

2011 ◽  
Vol 356-360 ◽  
pp. 1175-1179 ◽  
Author(s):  
Hong Tao Liu ◽  
Kui Hua Han ◽  
Sheng Li Niu ◽  
Chun Mei Lu
Keyword(s):  
Calcium Content ◽  
Isoconversional Method ◽  
Differential Method ◽  
Point Of View ◽  
Industrial Wastes ◽  
Heating Rates ◽  
Metal Impurities ◽  
Carbide Slag ◽  
High Calcium ◽  
Kinetic Calculations

The enhancement of alkaline industrial wastes on the desulfurization performance and utilization of limestone has already been found. In order to explore the reason of this phenomenon from the kinetic point of view, two typical alkaline wastes, carbide slag with a high calcium content and Bayer process red mud with more metal impurities, were adopted to research. Kinetic behavior of calcination reaction was calculated using the isoconversional method of Kissinger-Akahira-Sunose method (a differential method) and Flynn-Wall-Ozawa method (an integral method) at four different heating rates: 10, 20, 40 and 80 K•min-1. Values calculated by these two methods are very close, and the calculated result shows that calcination rate constant of modified limestone is obviously greater than that of original limestone, under the same calcination temperature, which means that alkaline wastes are advantageous to the thermal decomposition of limestone.

scholarly journals Ca2+ Content and Expression of an Acidocalcisomal Calcium Pump Are Elevated in Intracellular Forms ofTrypanosoma cruzi

1998 ◽  
Vol 18 (4) ◽  
pp. 2309-2323 ◽  
Author(s):  
Hong-Gang Lu ◽  
Li Zhong ◽  
Wanderley de Souza ◽  
Marlene Benchimol ◽  
Silvia Moreno ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Ionic Composition ◽  
Calcium Content ◽  
Protein Product ◽  
Calcium Pump ◽  
Calculated Molecular Mass ◽  
Transmission Electron ◽  
Intracellular Parasites ◽  
High Calcium ◽  
Microscopy Analysis

ABSTRACT The survival of a eukaryotic protozoan as an obligate parasite in the interior of a eukaryotic host cell implies its adaptation to an environment with a very different ionic composition from that of its extracellular habitat. This is particularly important in the case of Ca2+, the intracellular concentration of which is 3 orders of magnitude lower than the extracellular value. Ca2+entry across the plasma membrane is a widely recognized mechanism for Ca2+ signaling, needed for a number of intracellular processes, and obviously, it would be restricted in the case of intracellular parasites. Here we show that Trypanosoma cruzi amastigotes possess a higher Ca2+ content than the extracellular stages of the parasite. This correlates with the higher expression of a calcium pump, the gene for which was cloned and sequenced. The deduced protein product (Tca1) of this gene has a calculated molecular mass of 121,141 Da and exhibits 34 to 38% identity with vacuolar Ca2+-ATPases of Saccharomyces cerevisiae and Dictyostelium discoideum, respectively. The tca1 gene suppresses the Ca2+hypersensitivity of a mutant of S. cerevisiae that has a defect in vacuolar Ca2+ accumulation. Indirect immunofluorescence and immunoelectron microscopy analysis indicate that Tca1 colocalizes with the vacuolar H+-ATPase to the plasma membrane and to intracellular vacuoles of T. cruzi. These vacuoles were shown to have the same size and distribution as the calcium-containing vacuoles identified by the potassium pyroantimoniate-osmium technique and as the electron-dense vacuoles observed in whole unfixed parasites by transmission electron microscopy and identified in a previous work (D. A. Scott, R. Docampo, J. A. Dvorak, S. Shi, and R. D. Leapman, J. Biol. Chem. 272:28020–28029, 1997) as being acidic and possessing a high calcium content (i.e., acidocalcisomes). Together, these results suggest that acidocalcisomes are distinct from other previously recognized organelles present in these parasites and underscore the ability of intracellular parasites to adapt to the hostile environment of their hosts.

scholarly journals Calcium content and high calcium adaptation of plants in karst areas of southwestern Hunan, China

2018 ◽  
Vol 15 (9) ◽  
pp. 2991-3002 ◽  
Author(s):  
Xiaocong Wei ◽  
Xiangwen Deng ◽  
Wenhua Xiang ◽  
Pifeng Lei ◽  
Shuai Ouyang ◽  
...  
Keyword(s):  
Plant Species ◽  
Calcium Content ◽  
Vegetation Restoration ◽  
Plant Functional Groups ◽  
Ecological Problem ◽  
Rocky Desertification ◽  
Exchangeable Ca ◽  
High Calcium ◽  
Karst Areas ◽  
Ecosystem Reconstruction

Abstract. Rocky desertification is a major ecological problem of land degradation in karst areas. In these areas, the high soil calcium (Ca) content has become an important environmental factor that can affect the restoration of vegetation. Consequently, the screening of plant species that can adapt to high Ca soil environments is a critical step in vegetation restoration. In this study, three grades of rocky desertification sample areas were selected in karst areas of southwestern Hunan, China (LRD: light rocky desertification; MRD: moderate rocky desertification; and IRD: intense rocky desertification). Each grade of these sample areas had three sample plots in different slope positions, each of which had four small quadrats (one in rocky-side areas, three in non-rocky-side areas). We measured the Ca content of leaves, branches, and roots from 41 plant species, as well as soil total Ca (TCa) and exchangeable Ca (ECa) at depths of 0–15, 15–30, and 30–45 cm in each small quadrat. The results showed that the soil Ca2+ content in rocky-side areas was significantly higher than that in non-rocky-side areas (p<0.05). The mean soil TCa and ECa content increased gradually along with the grade of rocky desertification, in the order IRD > MRD > LRD. For all plant functional groups, the plant Ca content of aboveground parts was significantly higher than that of the belowground parts (p<0.05). The soil ECa content had significant effects on plant Ca content of the belowground parts but had no significant effects on plant Ca content of the aboveground parts. Of the 41 plant species that were sampled, 17 were found to be dominant (important value > 1). The differences in Ca2+ content between the aboveground and belowground parts of the 17 dominant species were calculated, and their correlations with soil ECa content were analyzed. The results showed that these 17 species can be divided into three categories: Ca-indifferent plants, high-Ca plants, and low-Ca plants. These findings provide a vital theoretical basis and practical guide for vegetation restoration and ecosystem reconstruction in rocky desertification areas.

Formation de Weddellite (CaC2O4∙2H2O) extracellulaire en culture in vitro par Paxillus involutus; signification de cette production pour la symbiose ecto- mycorhizienne

1984 ◽  
Vol 62 (6) ◽  
pp. 1116-1121 ◽  
Author(s):  
F. Lapeyrie ◽  
Monique Perrin ◽  
R. Pepin ◽  
G. Bruchet
Keyword(s):  
Calcium Oxalate ◽  
Culture Medium ◽  
Calcium Content ◽  
Ectomycorrhizal Fungus ◽  
Paxillus Involutus ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Calcium ◽  
Scanning Electron

Several forms of extracellular crystals have been observed in vitro on a semisynthetic culture medium. The conditions for their formation have not been determined. Their morphology and their localisation on the hyphal surface and in the culture medium have been investigated by means of scanning electron microscopy. These crystals have been identified as dehydrated calcium oxalate (Weddellite) using x-ray diffraction methods. Their high calcium content has been demonstrated with the scanning electron microprobe, by detecting the x-ray emission of calcium. The significance of calcium oxalate production by an ectomycorrhizal fungus is discussed.

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