scholarly journals Solvent-mediated Isotope Effects Strongly Influence the Early Stages of Calcium Carbonate Formation: Exploring D2O vs. H2O in a Combined Computational and Experimental Approach

2021 ◽  
Author(s):  
Michael King ◽  
Jonathan Thomas Avaro ◽  
Christine Peter ◽  
Karin Hauser ◽  
Denis Gebauer
Keyword(s):  
Calcium Carbonate ◽  
Heavy Water ◽  
Experimental Approach ◽  
Isotope Effects ◽  
Experimental Studies ◽  
Reaction Pathways ◽  
Solvent Exchange ◽  
Early Stages ◽  
Carbonate Formation

In experimental studies, heavy water (D2O) is employed, e.g., so as to shift the spectroscopic solvent background, but any potential effects of this solvent exchange on reaction pathways are often...

An experimental approach to the development of the ear capsule in the turtle, Chelydra serpentina

Development ◽  
1965 ◽  
Vol 13 (2) ◽  
pp. 141-149
Author(s):  
M. J. Toerien
Keyword(s):  
Recent Work ◽  
Experimental Approach ◽  
Experimental Studies ◽  
Chelydra Serpentina ◽  
Medial Aspect ◽  
Early Stages ◽  
Otic Placode ◽  
Auditory Region

The effects of the elimination of the otic placode or otocyst on the development of the cartilaginous ear capsule and columella auris have been observed in several fishes, amphibians and birds and are summarized by de Beer (1937), Yntema (1955) and Benoit (1957). More recent work includes that of Benoit (1960) and Toerien (1963). Except in the fish Acipenser (Filatow, 1930) the development of a cartilaginous ear capsule is completely suppressed following the removal of the otocyst. The effect of the operation on the development of the columella is not so clear and the resultant deficiency in the medial aspect has been interpreted in various ways. Yntema's (1965) method for using turtle eggs has made the early stages of reptilian embryos available for experimental studies. The purpose of the present investigation, therefore, is to study the effect of the removal of the placode on the development of the auditory region in yet another vertebrate class

NON-DESTRUCTIVE EXPERIMENTS AND MODELING OF CALCIUM CARBONATE FORMATION IN SOILS

2020 ◽  
Author(s):  
Carolyn D. Bland ◽  
◽  
Timothy M. Gallagher ◽  
Daniel O. Breecker
Keyword(s):  
Calcium Carbonate ◽  
Carbonate Formation ◽  
Non Destructive

An Experimental Approach to the Function of Classic Maya Chultuns

1971 ◽  
Vol 36 (3) ◽  
pp. 322-335 ◽  
Author(s):  
Dennis E. Puleston
Keyword(s):  
Experimental Approach ◽  
Experimental Studies ◽  
Water Storage ◽  
Food Storage ◽  
Food Crop ◽  
Traditional Foods ◽  
Long Term Storage ◽  
Brosimum Alicastrum ◽  
Term Storage

AbstractExperimental techniques have provided an exciting breakthrough for the functional analysis of Maya chultuns. While deep cistern-like chultuns, common at certain sites in the northern lowlands, have been shown to be functional for water storage, smaller lateral-chambered chultuns characteristic of certain parts of the southern lowlands probably had a very different function. Excavation and examination of the latter features, in light of a whole range of possibilities, suggest that they were constructed to be used for food storage. Experimental studies, however, reveal them to be unsuitable for the storage of most traditional foods, including maize. At least one local food crop, the seed of the ramon (Brosimum alicastrum, Moraceae), appears to be ideally suited for long-term storage under these conditions. Chambers constructed beneath platforms in the northern lowlands may have been used for the storage of maize. A need for more experimental work is indicated.

scholarly journals The Influence of Finely Ground Mineral Admixture (FGMA) on Efflorescence

2013 ◽  
Vol 4 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Ong Ming Wei ◽  
Norsuzailina Mohamed Sutan
Keyword(s):  
Calcium Carbonate ◽  
Chemical Analysis ◽  
Mineral Admixture ◽  
Partial Replacement ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Cement Replacement ◽  
Carbonate Formation

Efflorescence phenomenon on concrete is not new and found in the form of white deposits on surfaces of concrete. Incorporation of Finely Ground Mineral Admixture (FGMA) in concrete to prevent occurrence of efflorescence is based on reduction of portlandite, densified microstructure and thus enhanced watertightness. The magnitude of efflorescence in term of percentage of calcium carbonate formation of FGMA modified mortar were evaluated at water-cement ratio of 0.3, 0.4 and 0.5 with 10%, 20%, and 30% of cement replacement by weight. The samples were tested with chemical analysis at 7, 14, 21, 28, 60 and 90 days. The FGMA additions into mortar were comparing with ordinary mortar to evaluate enhanced performance of FGMA modified mortar toward efflorescence. The results of this experiment showed that addition of FGMA into mortar caused less formation of calcium carbonate as partial replacement of cement with certain w/c ratio and percentage of cement replacement.

scholarly journals INFLUENCE OF MICROBIAL CARBONATE MINERALIZATION ON HYDROPHOBICITY OF A CEMENT STONE SURFACE

2020 ◽  
pp. 19-25
Author(s):  
U. Duhanina ◽  
V. Strokova ◽  
D. Balickiy
Keyword(s):  
Calcium Carbonate ◽  
Experimental Studies ◽  
Wetting Angle ◽  
Cement Stone ◽  
Stone Surface ◽  
Lysinibacillus Sphaericus ◽  
Average Value ◽  
Microbial Carbonate ◽  
Contact Wetting Angle ◽  
The Relationship

The effect of microbial carbonate mineralization on increasing the hydrophobicity of the cement stone surface is theoretically justified and experimentally confirmed. Based on experimental studies and analysis of literature data, the main stages of microbial-induced sedimentation of calcium carbonate on the surface of a cement stone are formulated. Changes in the morphology of the cement stone surface due to crystalline new formations formed during biomineralization in the postgenetic period are described. It is shown that biocolmatation of the interstitial space of a cement stone by crystalline new formations leads to an increase in hydrophobicity, as evidenced by an increase in the contact wetting angle. The relationship between the change in the concentration of calcium in neoplasms and the average value of the contact wetting angle on the surface of the cement stone from the type of bacterial culture is established. According to chemical and morphological analysis of bioinduction tumors on the surface of samples and also evaluation of changes of the contact angle compared to the original index for cement, bacterial cultures are ranked in order to increase the efficiency of use for sedimentation of calcium carbonate with their participation, as well as increase of cement materials hydrophobicity in the following sequence: Sporosarcina pasteurii  Bacillus megaterium  Lysinibacillus sphaericus  Bacillus pumilus.

Structural characterization of amorphous calcium carbonate-binding protein: an insight into the mechanism of amorphous calcium carbonate formation

2013 ◽  
Vol 453 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Jingtan Su ◽  
Xiao Liang ◽  
Qiang Zhou ◽  
Guiyou Zhang ◽  
Hongzhong Wang ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Binding Sites ◽  
Binding Protein ◽  
Homology Modelling ◽  
Size Exclusion ◽  
Structural Basis ◽  
Amorphous Calcium Carbonate ◽  
Carbonate Formation

ACC (amorphous calcium carbonate) plays an important role in biomineralization process for its function as a precursor for calcium carbonate biominerals. However, it is unclear how biomacromolecules regulate the formation of ACC precursor in vivo. In the present study, we used biochemical experiments coupled with bioinformatics approaches to explore the mechanisms of ACC formation controlled by ACCBP (ACC-binding protein). Size-exclusion chromatography, chemical cross-linking experiments and negative staining electron microscopy reveal that ACCBP is a decamer composed of two adjacent pentamers. Sequence analyses and fluorescence quenching results indicate that ACCBP contains two Ca2+-binding sites. The results of in vitro crystallization experiments suggest that one Ca2+-binding site is critical for ACC formation and the other site affects the ACC induction efficiency. Homology modelling demonstrates that the Ca2+-binding sites of pentameric ACCBP are arranged in a 5-fold symmetry, which is the structural basis for ACC formation. To the best of our knowledge, this is the first report on the structural basis for protein-induced ACC formation and it will significantly improve our understanding of the amorphous precursor pathway.

scholarly journals Mechanisms of aortic valve calcification: the LDL-density-radius theory: a translation from cell signaling to physiology

2010 ◽  
Vol 298 (1) ◽  
pp. H5-H15 ◽  
Author(s):  
Nalini M. Rajamannan
Keyword(s):  
Risk Factors ◽  
Severe Aortic Stenosis ◽  
Elevated Serum ◽  
Experimental Studies ◽  
Atherosclerotic Lesion ◽  
Disease Process ◽  
Prognostic Indicator ◽  
Epidemiologic Studies ◽  
Factors Associated ◽  
Early Stages

Recent epidemiologic studies have revealed the risk factors associated for vascular atherosclerosis, including the male sex, smoking, hypertension, and elevated serum cholesterol, similar to the risk factors associated with the development of AV stenosis. An increasing number of models of experimental hypercholesterolemia demonstrate features of atherosclerosis in the AV, which are similar to the early stages of vascular atherosclerotic lesions. Experimental and clinical studies demonstrate that the hypercholesterolemic AV develops an atherosclerotic lesion which is proliferative and expresses high levels of osteoblast bone markers which mineralize over time to form bone. Calcification, the end-stage process of the disease, is necessary to understand as a prognostic indicator in the modification of this cellular process before it is too late. In summary, these findings suggest that medical therapies may have a potential role in patients in the early stages of this disease process to slow the progression to severe aortic stenosis and to delay the timing of the need for surgery. The translation of these experimental studies to clinical practice will be important to understand the potential for medical therapy for this disease process.

scholarly journals Properties of Feshbach and “shape”-resonances in ozone and their role in recombination reactions and anomalous isotope effects

2018 ◽  
Vol 212 ◽  
pp. 259-280 ◽  
Author(s):  
Alexander Teplukhin ◽  
Dmitri Babikov
Keyword(s):  
Isotope Effects ◽  
Reaction Pathways ◽  
Recombination Reactions ◽  
Shape Resonances

Three reaction pathways for formation of symmetric and asymmetric isotopologues of ozone.

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