scholarly journals Does bacterial weathering play a significant role in rock weathering?

2021 ◽  
Author(s):  
Adil Binal ◽  
Aylin Sel
Keyword(s):  
Significant Role ◽  
Chemical Elements ◽  
Bacterial Species ◽  
Building Stone ◽  
Rock Weathering ◽  
Experimental Conditions ◽  
Rock Samples ◽  
Rock Types ◽  
Stone Materials ◽  
Biological Weathering

Abstract Bacterial weathering plays a significant role in rock weathering, yet only a limited number of studies was conducted on this topic. The recent rapid developments in geomicrobiology are expected to increase the pace of research in this area. The extent and duration of the biological weathering processes on mineral and rock samples and minerals preferred by bacteria are still not fully understood due to the wide variety of both bacterial species and rock types. Biological weathering of rock types found in Turkey has also not been studied before. Here, we investigated the effects of two species of bacteria actively contributing to rock weathering on three rock types commonly used as building stone materials in Turkey. Granite, andesite, and limestone samples could interact with Bacillus species (B. subtilis and B. pumilus) in closed system reactors. Samples obtained from these reactors were analysed via Scanning Electron Microscopy (SEM) monitoring to identify morphological features and chemical composition changes. Chemical elements consumed most by bacteria were identified. Changes in the colour index were determined via RGB measurements. The effects of experimental conditions on bacterial growth were monitored via daily optical density measurements. The effects of bacteria on the physical properties of rock samples were also evaluated. B. subtilis and B. pumilus were found to be more aggressive on limestone/andesite and granite, respectively.

scholarly journals Comparation of Pressed Powder Pellet and Fused Glass Bead Preparation Techniques for Mayor Elements Analysis of Rock Samples using X-Ray Fluorescence (XRF)

2020 ◽  
Vol 31 (2) ◽  
pp. 24-27
Author(s):  
Asep Rohiman ◽  
Agus Saiful Arifin
Keyword(s):  
Sample Preparation ◽  
Glass Bead ◽  
Chemical Elements ◽  
Preparation Technique ◽  
Standard Samples ◽  
X Ray ◽  
Rock Samples ◽  
Minor Elements ◽  
Rock Types ◽  
Analysis Process

The composition of chemical elements in rock samples can be used as a tool for classifying rock types, predicting the depositional environment, rock age, and the tectonic environment in which the rock is formed. X-Ray Fluorescence (XRF) is one of the instruments used to analyze rock samples. The advantage of using XRF analysis is that the analysis process can be done more quickly, easily, accurately, and does not damage the sample. However, before measurements are made using the XRF instrument it needs to be supported by an appropriate sample preparation process. In this study, optimal conditions in the standard (CRM) rock sample preparation of GBW 07105 and JR-1 have been studied. The parameters studied were variations in the composition ratio of Cellulose Mycro Crystalin (CMC) with standard (CRM) samples, namely 1: 4 and 1: 3. The technique of mixing the sample is done by using a mortar grinder and a shaker. Optimization of sample preparation was carried out using pressed powder pellet and fused glass bead techniques. Based on the data obtained from the analysis results the best ratio of binders to standard samples is 1: 3. The pressed powder pellet preparation technique is the best technique in analyzing samples using the X-Ray Fluorescence method. Further studies also need to be carried out to analyze minor elements and traces (REEs).

QEMSCAN-Assisted Interpretation of Imbibition Capillary Pressure for Multiporosity Carbonate Rocks

SPE Journal ◽  
2020 ◽  
pp. 1-17
Author(s):  
Aymen Alramadhan ◽  
Yildiray Cinar
Keyword(s):  
Capillary Pressure ◽  
Numerical Models ◽  
Rock Composition ◽  
Rock Samples ◽  
Rock Types ◽  
Centrifuge Tests ◽  
Medium Permeability ◽  
Mercury Injection Capillary Pressure ◽  
The Impact ◽  
Selection Of

Summary In this paper, we present an experimental study that explores the potential links between the imbibition capillary pressure Pci and the pore systems and/or mineralogy for carbonate reservoirs undergoing waterflood. A systematic workflow has been formulated to ensure the data quality ofPci, minimize uncertainty in derivingPci from centrifuge tests, and analyze the data considering the pore-size distribution from mercury injection capillary pressure (MICP) and mineralogy from Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN). The workflow starts with assessing the centrifuge production data for gravity-capillary equilibrium at each speed. Then, the quality-checked data are used to generate six differentPci curves using analytical and numerical models. The resulting curves provide a measure of the variability in solutions for various rock types and assist in the selection of the most-representativePci curve. Finally, the representative Pci curves of all rock samples are analyzed together with the MICP and QEMSCAN data to examine the change in Pci curves as a result of changes in the number and character of rock types, pore systems, dominant pore-throat radii, and mineralogy. Findings from this study shed light on the impact of mineralogy and pore systems on Pci. From the mineralogy perspective, the presence of dolomite, microporous calcite, or rutile and anatase (TiO2) within the rock composition is found to affect the Pci of the carbonate samples used in this study. The rock samples with these minerals should be separated from other bimodal samples before attempting to obtain a correlation between Pci and pore systems. The data analysis further reveals that some bimodal samples of medium permeability yield a better waterflood imbibition efficiency than those of the high-permeability samples. This observation is attributed to a better communication between the micropore and macropore systems, and a closer proximity of the peak radii of the micro- and macropore systems of the medium-permeability samples.

scholarly journals THE FIBRINOLYTIC ACTIVITY OF HEMOLYTIC STREPTOCOCCI

1933 ◽  
Vol 58 (4) ◽  
pp. 485-502 ◽  
Author(s):  
William S. Tillett ◽  
R. L. Garner
Keyword(s):  
Fibrinolytic Activity ◽  
Bacterial Species ◽  
Surrounding Medium ◽  
Fibrin Clot ◽  
Animal Origin ◽  
Complete Dissolution ◽  
Experimental Conditions ◽  
Plasma Clot ◽  
Human Fibrinogen ◽  
Normal Human

Broth cultures of hemolytic streptococci derived from patients are capable of rapidly liquefying normal human fibrin clot. The active fibrinolytic principle is also contained in sterile, cell-free filtrates of broth cultures. The degree of activity of filtrates parallels the activity of whole broth cultures sufficiently closely to indicate that large amounts of the fibrinolytic substance are freely excreted into the surrounding medium and pass readily through Berkefeld V, Seitz, and Chamberland filters. The occurrence of fibrinolysis is most strikingly observed when plasma or fibrinogen is mixed with active cultural material before clot formation is effected. Under the standard experimental conditions described, complete dissolution of human plasma clot (whole oxalated plasma + CaCl2) occurs in about 10 minutes; complete dissolution of human fibrinogen clot (chemically isolated fibrinogen + thrombin) takes place in about 2 minutes. Titration of filtrate activity is recorded in Table IV. Twenty-eight strains of Streptococcus hemolyticus, isolated from patients suffering from various manifestations of streptococcus infection, have been tested for the capacity to liquefy fibrin clot. Broth cultures of all of the strains induced fibrinolysis. Of 18 strains of Streptococcus hemolyticus of animal origin, only three were capable of causing dissolution of clot. Completely negative results were obtained with 38 strains of other bacterial species. The list is presented on pages 492 and 493. The plasma of many patients recovered from acute hemolytic streptococcus infections, when clotted in the presence of active cultures, is highly resistant to fibrinolysis. Furthermore, serum, derived from patients whose plasma clot is resistant, often confers on normal plasma clot an antifibrinolytic property. One example of the resistance possessed by the blood of convalescent patients is presented in this report. A second paper, now in preparation, will give in detail a large number of observations on the relation of infection to the development of resistance to the fibrinolytic activity of hemolytic streptococci. In contrast to the susceptibility of normal human fibrin clot to liquefaction by active culture, normal rabbit fibrin clot is totally resistant to dissolution when tested under comparable conditions. The insusceptibility of rabbit fibrin clot is manifest provided the coagulum is composed of rabbit constituents. When human thrombin is used to clot rabbit plasma or fibrinogen in the presence of active cultures, fibrinolysis is not prohibited. The rôle of thrombin in determining the resistance or susceptibility of rabbit fibrin to dissolution offers a suggestive approach to problems relating to the underiving mechanism.

New fluorinated acrylic polymers for improving weatherability of building stone materials

1997 ◽  
Vol 32 (1-4) ◽  
pp. 43-50 ◽  
Author(s):  
F Ciardelli ◽  
M Aglietto ◽  
L Montagnini di Mirabello ◽  
E Passaglia ◽  
S Giancristoforo ◽  
...  
Keyword(s):  
Building Stone ◽  
Acrylic Polymers ◽  
Stone Materials

The geology of the western approaches of the English Channel. II. Geological interpretation aided by boomer and sparker records

1965 ◽  
Vol 248 (749) ◽  
pp. 315-351 ◽  
Keyword(s):  
Upper Cretaceous ◽  
Geological Structure ◽  
Lower Jurassic ◽  
Energy Output ◽  
Red Sandstone ◽  
Geological Interpretation ◽  
Rock Samples ◽  
Rock Types ◽  
Sea Bed ◽  
Geological Boundaries

A geological map of about 1700 square miles of the sea-bed south of the Cornish coast between Bolt Head and Fowey was prepared by coring and dredging for rock samples; a boomer-sparker survey was then selected in relation to the supposed geology to fix more precisely the geological boundaries and to ascertain the geological structure of the rocks underlying the sea-bed, in this case to a depth of about 400 ft. The acoustic apparatus is described; the records are interpreted according to mathematical analysis and the probable limits of inaccuracy assessed. 91 rock samples are described lithologically and the microfossils identified in all productive cases to give the stratigraphical ages. In some samples radiometric determinations have been made of the ages of the metamorphism of ‘gneisses’ and slates. All contacts are unconformable between the following major divisions: Metamorphic Complex, ?Devonian, New Red Sandstone, Upper Cretaceous, Eocene; the base of the Lias is unknown but these rocks form an inlier and are unconformably surrounded by the Upper Cretaceous. Pre-Santonian, Santonian, Campanian, Lower and Upper Maestrichtian are recognized; Danian appears conformable to the Maestrichtian but is included in the Tertiary although it is unconformably succeeded by Eocene; there is presumptive evidence of ? Oligocene in one cored sample. True-scale sections drawn along the course of the ship using corrected apparent dips and applying different velocities to different rock-types gave the following approximate thicknesses: New Red Sandstone, 3100 ft.; Lower Jurassic, greater than 640 ft. (base not seen); Upper Cretaceous, 1225 ft., comprising Pre-Santonian 75 ft., Santonian 175 ft., Campanian 375 ft., Maestrichtian 600 ft.; Danian, 375 ft.; Eocene, greater than 430 ft. (top not seen). In this particular combined experiment the boomer-sparker equipment has proved invaluable in correcting geological boundaries, in determining geological structure which with present coring methods at sea is almost impossible to detect, and in providing reasonably reliable figures of the thickness of major stratigraphical divisions. These two geological and geophysical investigations are mutually complementary and, with much greater energy output than was used in 1960, the promise is great for the determination of geological structure many thousands of feet below the sea-bed.

scholarly journals The effect of saturation on the physical and mechanical behavior of some rock samples

2021 ◽  
Vol 2 (3) ◽  
pp. 23-31
Author(s):  
Mohammad Taghi Hamzaban
Keyword(s):  
Tensile Strength ◽  
Mechanical Behavior ◽  
Physical And Mechanical Properties ◽  
Intact Rock ◽  
P Wave ◽  
Mechanical Parameters ◽  
Brazilian Tensile Strength ◽  
Rock Samples ◽  
Rock Types ◽  
Major Factors

Different major factors control the strength of solid rocks. Moisture content is one of the most important factors, which can change the physical and mechanical behavior of intact rock as well as rock mass. Several early studies have shown that rock is weaker if tested wet rather than dry. In this paper, the density, P-wave velocity, uniaxial compressive strength, Brazilian tensile strength, and modulus of elasticity of seven different intact rock samples were measured under both dry and saturated conditions. The porosity of the samples was reported as well. Based on the obtained results, some correlations were proposed for estimating the saturated physical and mechanical properties from dry ones. The proposed correlations include different rock types and are more general than the previously reported ones. Comparing the obtained results showed that the mechanical and physical properties of weaker samples are more sensitive to the saturation process. Moreover, among the different mechanical parameters, Brazilian tensile strength exhibited more sensitivity to saturation. Comparing the results with the calculated porosities revealed that porosity is one of the key factors in the effect of saturation on physical and mechanical parameters. It seems that in the more porous rock samples, greater changes in the different measured parameters occur after saturation.

scholarly journals Pétrographie characterization of rocks from the Mirabello bay region, Crete, and its application to Minoan archaeology: the provenance of stone implements from Minoan sites

2007 ◽  
Vol 40 (4) ◽  
pp. 1768 ◽  
Author(s):  
H. M. Dierckx ◽  
B. Tsikouras
Keyword(s):  
Raw Materials ◽  
Igneous Rocks ◽  
Metamorphic Rocks ◽  
Rock Samples ◽  
Rock Types ◽  
Source Regions ◽  
Time Period

The Minoans of East Crete used a variety of igneous and metamorphic rocks as stone implements. These were probably procured in dry riverbeds and beaches located in a region along the Bay of Mirabello or from an onlap conglomerate, which geologically dominates that region and contains rock types of igneous, metamorphic and sedimentary origin. Several rock samples were collected for pétrographie investigation to examine and confirm the source for the igneous rocks. Detailed pétrographie description of natural samples provides the identification of the rocks employed by Minoans and confirms the source of their origin. Apparently the Minoans were able to evaluate the hardness of the stones procured according to the desirable usage and their expected fatigue, thus avoiding unnecessary timeconsuming treatment. The identification of the variable lithotypes used for these implements and the verification of their source regions reveal the time it took to procure the raw materials as well as the time period during which the rocks were employed.

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