Displaying all 6 publications

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  1. Esfandyari Bayat A, Junin R, Derahman MN, Samad AA
    Chemosphere, 2015 Sep;134:7-15.
    PMID: 25889359 DOI: 10.1016/j.chemosphere.2015.03.052
    The impact of ionic strength (from 0.003 to 500mM) and salt type (NaCl vs MgCl2) on transport and retention of titanium dioxide (TiO2) nanoparticles (NPs) in saturated limestone porous media was systematically studied. Vertical columns were packed with limestone grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolent-visible spectrometry. Presence of NaCl and MgCl2 in the suspensions were found to have a significant influence on the electrokinetic properties of the NP aggregates and limestone grains. In NaCl and MgCl2 solutions, the deposition rates of the TiO2-NP aggregates were enhanced with the increase in ionic strength, a trend consistent with traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Furthermore, the NP aggregates retention increased in the porous media with ionic strength. The presence of salts also caused a considerable delay in the NPs breakthrough time. MgCl2 as compared to NaCl was found to be more effective agent for the deposition and retention of TiO2-NPs. The experimental results followed closely the general trends predicted by the filtration and DLVO calculations. Overall, it was found that TiO2-NP mobility in the limestone porous media depends on ionic strength and salt type.
    Matched MeSH terms: Calcium Carbonate/analysis*
  2. Moharir KN, Pande CB, Gautam VK, Singh SK, Rane NL
    Environ Res, 2023 Jul 01;228:115832.
    PMID: 37054834 DOI: 10.1016/j.envres.2023.115832
    The Damoh district, which is located in the central India and characterized by limestone, shales, and sandstone compact rock. The district has been facing groundwater development challenges and problems for several decades. To facilitate groundwater management, it is crucial to monitoring and planning based on geology, slope, relief, land use, geomorphology, and the types of the basaltic aquifer in the drought-groundwater deficit area. Moreover, the majority of farmers in the area are heavily dependent on groundwater for their crops. Therefore, delineation of groundwater potential zones (GPZ) is essential, which is defined based on various thematic layers, including geology, geomorphology, slope, aspect, drainage density, lineament density, topographic wetness index (TWI), topographic ruggedness index (TRI), and land use/land cover (LULC). The processing and analysis of this information were carried out using Geographic Information System (GIS) and Analytic Hierarchy Process (AHP) methods. The validity of the results was trained and tested using Receiver Operating Characteristic (ROC) curves, which showed training and testing accuracies of 0.713 and 0.701, respectively. The GPZ map was classified into five classes such as very high, high, moderate, low, and very low. The study revealed that approximately 45% of the area falls under the moderate GPZ, while only 30% of the region is classified as having a high GPZ. The area receives high rainfall but has very high surface runoff due to no proper developed soil and lack of water conservation structures. Every summer season show a declined groundwater level. In this context, results of study area are useful to maintain the groundwater under climate change and summer season. The GPZ map plays an important role in implementing artificial recharge structures (ARS), such as percolation ponds, tube wells, bore wells, cement nala bunds (CNBs), continuous contour trenching (CCTs), and others for development of ground level. This study is significant for developing sustainable groundwater management policies in semi-arid regions, that are experiencing climate change. Proper groundwater potential mapping and watershed development policies can help mitigate the effects of drought, climate change, and water scarcity, while preserving the ecosystem in the Limestone, Shales, and Sandstone compact rock region. The results of this study are essential for farmers, regional planners, policy-makers, climate change experts, and local governments, enabling them to understand the groundwater development possibilities in the study area.
    Matched MeSH terms: Calcium Carbonate/analysis
  3. Mohammed AU, Aris AZ, Ramli MF, Isa NM, Arabi AS, Jabbo JN
    Environ Geochem Health, 2023 Jun;45(6):3891-3906.
    PMID: 36609946 DOI: 10.1007/s10653-022-01468-6
    Multiple interactions of geogenic and anthropogenic activities can trigger groundwater pollution in the tropical savanna watershed. These interactions and resultant contamination have been studied using applied geochemical modeling, conventional hydrochemical plots, and multivariate geochemometric methods, and the results are presented in this paper. The high alkalinity values recorded for the studied groundwater samples might emanate from the leaching of carbonate soil derived from limestone coupled with low rainfall and high temperature in the area. The principal component analysis (PCA) unveils three components with an eigenvalue > 1 and a total dataset variance of 67.37%; this implies that the temporary hardness of the groundwater and water-rock interaction with evaporite minerals (gypsum, halite, calcite, and trona) is the dominant factor affecting groundwater geochemistry. Likewise, the PCA revealed anthropogenic contamination by discharging [Formula: see text] [Formula: see text][Formula: see text] and [Formula: see text] from agricultural activities and probable sewage leakages. Hierarchical cluster analysis (HCA) also revealed three clusters; cluster I reflects the dissolution of gypsum and halite with a high elevated load of [Formula: see text] released by anthropogenic activities. However, cluster II exhibited high [Formula: see text] and [Formula: see text] loading in the groundwater from weathering of bicarbonate and sylvite minerals. Sulfate ([Formula: see text]) dominated cluster III mineralogy resulting from weathering of anhydrite. The three clusters in the Maiganga watershed indicated anhydrite, gypsum, and halite undersaturation. These results suggest that combined anthropogenic and natural processes in the study area are linked with saturation indexes that regulate the modification of groundwater quality.
    Matched MeSH terms: Calcium Carbonate/analysis
  4. Fadilah A, Zuki AB, Loqman MY, Zamri-Saad M, Norimah Y, Asnah H
    Med J Malaysia, 2004 May;59 Suppl B:178-9.
    PMID: 15468876
    The study was carried out to evaluate macroscopically the ability of coral to repair a large size bone defect. A total 12 adult, male sheep were used in the study. The large bone defect (2.5cm x 0.5cm x 0.5cm) was created surgically on the left proximal femur and replaced by a block of coral (Porites sp.). Radiographs were obtained immediately after surgery and at 2, 4, 8 and 12 weeks post-implantation. Ultrasonographic examinations were carried out every 2 weeks after implantation up to 12 weeks using ultrasound machine (TOSHIBA Capasee II) connected with 7MHz frequency transducer. The sheep were euthanased at 2, 4, 8, and 12 weeks post-implantation and the bone examined grossly. Both ultrasonographs and radiographs taken at 8 and 12 weeks showed that the implants had been resorbed and left the space that much reduced in size. There was no sign of implant rejection observed in all animals. The results showed that processed coral has potential to become bone substitute for reconstructive bone surgery.
    Matched MeSH terms: Calcium Carbonate/analysis*
  5. Abu Bakar SH, Hussein Z, Hee SL, Fazan F
    Med J Malaysia, 2004 May;59 Suppl B:81-2.
    PMID: 15468829
    Hydroxyapatite, (HA; Ca1O(PO4)6(OH)2) has been successfully applied in medical and dental applications for several years due to its excellent biocompatibility. The usage of HA in Malaysia, however, is limited due to the lack of availability. Therefore the aim of this work is to produce HA materials from both pure chemicals and from Malaysian natural limestone precursors, and to compare their bulk properties. However, parts of Malaysian natural limestone deposits actually consist of a combination of Ca(OH)2 and CaCO3. In order to utilise the limestone to produce HA material, the combination of these commercially pure chemicals as HA precursors should still work. In order to test this hypothesis, two HAs were produced by wet synthesis technique utilising (a) combination of Ca(OH)2 + CaCO3 from pure commercial chemicals [WCC] and (b) a local natural limestone [WL] precursors. The HAs produced; WCC and WL, were compacted into discs and sintered at 1250 degrees C. The characterisations and evaluations conducted were XRD, SEM-EDX, FTIR and shrinkage factor. The results indicate that WL gives slightly better bulk properties compared to WCC.
    Matched MeSH terms: Calcium Carbonate/analysis
  6. Dorai CRT
    Med J Malaysia, 1987 Jun;42(2):119-21.
    PMID: 3503184
    A case of limy bile, i.e. bile in the gall bladder rendered radio-opaque due to excessive concentration of calcium carbonate, is reported and its pathogenesis discussed.
    Matched MeSH terms: Calcium Carbonate/analysis*
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