CaO Content Research Articles

Extracellular and intracellular effects of bioactive glass nanoparticles on osteogenic differentiation of bone marrow mesenchymal stem cells and bone regeneration in zebrafish osteoporosis model

Bioactive glass nanoparticles (BGNs) are well-recognized multifunctional biomaterials for bone tissue regeneration due to their capability to stimulate various cellular processes through released biologically active ions. Understanding the correlation between BGN composition and cellular responses is key to developing clinically usable BGN-based medical devices. This study investigated the influence of CaO content of binary SiO2-CaO BGNs (CaO ranging from 0 to 10 mol%) on osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and in vivo bone regeneration in zebrafish osteoporosis model. The results showed that BGNs could promote osteogenic differentiation of rBMSCs by indirectly releasing active ions or directly interacting with rBMSCs by internalization. In both situations, BGNs of a higher CaO content could promote the osteogenic differentiation of rBMSCs to a greater extent. The internalized BGNs could activate the transcription factors RUNX2 and OSX, leading to the expression of osteogenesis-related genes. The results in the zebrafish osteoporosis model indicated that the presence of BGNs of higher CaO contents could enhance bone regeneration and rescue dexamethasone-induced osteoporosis to a greater extent. These findings demonstrate that BGNs can stimulate osteogenic differentiation of rBMSCs by releasing active ions or internalization. A higher CaO content facilitates osteogenesis and bone regeneration of zebrafish as well as relieving dexamethasone-induced osteoporosis. The zebrafish osteoporosis model can be a potent tool for evaluating the in vivo bone regeneration effects of bioactive materials. Statement of significanceBioactive glass nanoparticles (BGNs) are increasingly used as fillers of nanocomposites or as delivery platforms of active ions to regenerate bone tissue. Various studies have shown that BGNs can enhance osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) by releasing active ions. However, the correlation between BGN composition and cellular responses and in vivo bone regeneration effect has still not been well investigated. Establishment of a suitable in vivo animal model for investigating this correlation is also challenging. The present study reports the influence of CaO content in binary SiO2-CaO BGNs on osteogenic differentiation of BMSCs extracellularly and intracellularly. This study also demonstrates the suitability of zebrafish osteoporosis model to investigate in vivo bone regeneration effect of BGNs.

Ash fusion behavior modification mechanisms of high-calcium coal by coal blending and its ash viscosity predication

In this paper, the ash fusion temperature (AFT) modification of high calcium Huolinhe lignite (HLH) with the addition of high aluminum Datong coal (DTC) and their corresponding mechanisms were investigated by an AFT tester, X-ray diffractometer, Raman spectrometer, and FactSage software. The AFTs of HLH mixtures increased gradually with the increasing DTC mass ratio due to their corresponding decrease in the total basic oxide content of CaO, MgO, Fe2O3, Na2O, and K2O. The formations and content increases of high melting-point minerals (anorthite, cordierite, and mullite), the gradual decrease in the ratios of no bridging-oxide bond/bridging-oxide bond (NBO/BO), and an increase in the R (R = (Q3 + Q2)/(Q1 + Q0)) value resulted in the increases in the AFT and ash viscosity. Considering the variations in the characteristics of AFT and ash viscosity, the 40.0–50.0 % DTC mass ratio might be suitable for HLH entrained-flow bed (EFB) gasification. The combination of AFT measurement and ash viscosity predication using FactSage provided a simple method to determine whether ash characteristics of coal were suitable for EFB gasification.

Sol-gel derived B2O3-CaO borate bioactive glasses with hemostatic, antibacterial and pro-angiogenic activities.

Sol-gel borate bioactive glasses (BGs) are promising ion-releasing biomaterials for wound healing applications. Here, we report the synthesis of a series of binary B2O3-CaO borate BGs (CaO ranging from 50 to 90 mol%) using a sol-gel-based method. The influence of CaO content in B2O3-CaO borate BG on morphology, structure and ion release behavior was investigated in detail. Reduced dissolution (ion release) and crystallization could be observed in borate BGs when CaO content increased, while the morphology was not significantly altered by increasing CaO content. Our results evidenced that the ion release behavior of borate BGs could be tailored by tuning the B2O3/CaO molar ratio. We also evaluated the in vitro cytotoxicity, hemostatic, antibacterial and angiogenic activities of borate BGs. Cytocompatibility was validated for all borate BGs. However, borate BGs exhibited composition-dependent hemostatic, antibacterial and angiogenic activities. Generally, higher contents of Ca in borate BGs facilitated hemostatic activity, while higher contents of B2O3 were beneficial for pro-angiogenic activity. The synthesized sol-gel-derived borate BGs are promising materials for developing advanced wound healing dressings, given their fast ion release behavior and favorable hemostatic, antibacterial and angiogenic activities.

Volatilization behavior of lead, zinc and sulfur from flotation products of low-grade Pb-Zn oxide ore by carbothermic reduction

Existing methods are difficult to directly treat the tailings of Lanping Pb-Zn deposit because of low Pb + Zn content. According to the characteristics of high CaO content (11%) in the flotation products of Lanping low-grade Pb-Zn oxide ore, a carbon thermal reduction method based on rotary hearth furnace (RHF) process was developed. When reaction temperature was above 1000 °C, CaO could realize the transformation of metal sulfides to oxides. Increasing reducing atmosphere was favor of the efficient volatilization of Zn and Pb and the trapping of S. The volatiles in reducing agents could promote the volatilization of zinc. The reduction effect of anthracite and thermal coal was better than that of charcoal. The volatilization rates of Zn and Pb exceeded 98% and 96%, respectively, under the conditions of 1250 °C, 30 min, 20% thermal coal addition and air atmosphere. High quality ZnO dust with a ZnO purity of 83% was obtained.

Machine Learning Based Reactivity Prediction of Fly Ash Type F Produced from South Korea

Fly ash (FA) is the most commonly used supplementary cementitious material in the world. However, the reactivity of FA varies substantially. In this study, new machine learning (ML) model has been developed to efficiently predict the amorphous content in FA type F. Compared to the existing ML model using types F and C of FA from different countries, this study more focused on the improved prediction of FA type F only produced from South Korea. It was found that the contents of CaO and SiO2 impact high in predicting the amount of aluminosilicate glass. However, the contribution of Al2O3 and Fe2O3 are ranked differently. The improved model algorithm was proposed as a combination of three ensemble techniques of bagging, boosting, and stacking. As a result of the test, the final model shows {R}^{2} of 0.80 in predicting the amount of aluminosilicate glass in FA type F.

Canola oil transesterification for biodiesel production using potassium and strontium supported on calcium oxide catalysts synthesized from oyster shell residues

This work studied the effect of K precursor comparing KNO3 and KHCO3 and the combination with SrO, supported on CaO from oyster shell and limestone (1:1 mass ratio) for transesterification canola oil to produce biodiesel. The loading of Sr and K were 9 wt% and were calcined at 800 °C. The catalytic transesterification evaluations were conducted at 60 °C, methanol/oil of 10, 8 wt% of the catalyst for 1 h, where SrK/CaO catalysts presented biodiesel yields above 80 %. Moreover, the Box-Behnken response surface design was used with reaction time, methanol-to-oil ratio, and temperature as factors using SrKH/CaO catalyst. In comparison to using KNO3, the KHCO3 increase the concentration of CaO. However, basicity and biodiesel yield were the same regardless of the K precursor. Incorporating K into Sr/CaO increased the particle size, the basicity, and the biodiesel yield. Furthermore, the design of experiments successfully showed an optimum methanol-to-oil ratio of 15, 46 °C, and 3 h. Nonetheless, the SrK/CaO catalysts presented a reusability of only two cycles. The incorporation of Sr and K did not avoid the lixiviation of the active sites, but they may retard this process the catalyst may be more active at low reaction times.

Slag chemistry, element distribution behaviors, and metallurgical balance of e-waste smelting process

The co-smelting of electronic waste (e-waste) in copper/lead pyrometallurgical processes is widely recognized as the preferred solution for sustainable development. However, aluminum and halogen elements in e-waste causes new challenges. To address this, the slag chemistry of high Al2O3-containing slag was studied, and the distribution behaviors of Au, Ag, Sn, and other elements in the copper alloy/slag/gas system were investigated in the presence of halogen elements (F/Cl/Br) using the equilibration method. The industrial practice of electronic waste smelting was modeled using METSIM, and the material and energy balances of one industrial process were obtained. Under the conditions of electronic waste smelting, the solubility of Al2O3 in the FexO–SiO2–Al2O3–CaO slag system decreased with increasing CaO content. When the CaO content was 20 wt%, and the Fe/SiO2 mass ratio was 0.62–0.95, the solubility of Al2O3 in the slag reached 20 wt%. When 1%–10% CaF2 was added, 93% of Au entered the metal phase. When the same amount of CaCl2 or CaBr2 was added, up to 32% Au entered the gas phase. When CaF2 was added to the system, 22%–49% of Ag entered the gas phase. However, when CaCl2 or CaBr2 was added, 3%–34% of Ag entered the gas phase. The proportion of tin in the gas and slag phases increased with increasing temperature or the addition of halides. The METSIM simulation results showed that under optimized conditions, the crude copper contained more than 90 wt% copper, the discharged slag contained approximately 0.5 wt% copper, and the recovery rates of copper, gold, and silver were ≥98%. The heat generated from raw materials and fuel accounted for the largest part of the heat income, representing 65.32% of the total.

U-Pb Geochronology, Geochemistry and Geological Significance of the Yongfeng Composite Granitic Pluton in Southern Jiangxi Province

The Yongfeng composite granitic pluton, located in the southern section of the Nanling area, is composed of the Yongfeng and Longshi biotite monzonitic granites. In order to reveal the genesis of this composite granitic pluton and its relationship with mineralization, this study conducted zircon U-Pb dating, whole-rock major and trace element analysis, and biotite electron probe analysis. The results show that the Yongfeng composite granitic pluton is rich in silicon and alkali, weakly peraluminous, and poor in calcium and iron. It shows the enrichment of light rare earth elements and a significant fractionation of light and heavy rare earth elements. It also shows the enrichment of large ion lithophile elements and depletion of Ba, K, P, Eu, and Ti relative to the primitive mantle. The contents of TFe2O3, MgO, CaO, TiO2, and P2O5 are low and decrease with increasing SiO2 content. The Yongfeng composite granitic pluton does not contain alkaline dark minerals. Its average zircon saturation temperature is 776 °C, average TFe2O3/MgO is 4.81, and average Zr + Nb + Ce + Y is 280.6 ppm, which correspond to a highly fractionated I-type granite. The Yongfeng and Longshi granites were respectively formed at 152.0 ± 1.0 Ma–151.3 ± 1.1 Ma and 148.9 ± 1.2 Ma. They were formed in the extensional tectonic setting during the post-orogenic stage, under the control of the breakup or retreat of the backplate after the subduction of the Pacific Plate into the Nanling hinterland. The magmatic system of the Yongfeng composite granitic pluton is characterized by high fractionation, high content of F, high temperature, and low oxygen fugacity, which is conducive to mineralization of Sn, Mo, and fluorite.

Geochemical Evidence for Genesis of Nb–Ta–Be Rare Metal Mineralization in Highly Fractionated Leucogranites at the Lalong Dome, Tethyan Himalaya, China

Leucogranites in the Lalong Dome are composed of two-mica granite, muscovite granite, albite granite, and pegmatite from core to rim. Albite granite-type Be–Nb–Ta rare metal ore bodies are hosted by albite granite and pegmatite. Based on field and petrographic observations and whole-rock geochemical data, highly differentiated leucogranites have been identified in the Lalong Dome. Two-mica granites, albite granites, and pegmatites yielded monazite ages of 23.6 Ma, 21.9 Ma, and 20.6 Ma, respectively. The timing of rare metal mineralization is 20.9 Ma using U–Pb columbite dating. Leucogranites have the following characteristics: high SiO2 content (>73 wt.%); peraluminosity with high Al2O3 content (13.6–15.2 wt.%) and A/CNK (mostly > 1.1); low TiO2, CaO, and MgO content; enrichment of Rb, Th, and U; depletion of Ba, Nb, Zr, Sr, and Ti; strong negative Eu anomalies; low εNd(t) values ranging from −12.7 to −9.77. These features show that the leucogranites are crust-derived high-potassium calc-alkaline and peraluminous S-type granites derived from muscovite dehydration melting under the water-absent condition, which possibly resulted from structural decompression responding to the activity of the South Tibetan detachment system (STDS). Geochemical data imply a continuous magma fractional crystallization process from two-mica granites through muscovite granites to albite granites and pegmatites. The differentiation index (Di) gradually strengthens from two-mica granite, muscovite granite, and albite granite to pegmatite, in which albite granite and pegmatite are highest (Di = 94). The Nb/Ta and Zr/Hf ratios of albite granite and pegmatite were less than 5 and 18, respectively, which suggests that albite granite and pegmatite belong to rare metal granites and have excellent potential for rare metal mineralization.

Mesoarchean synchronous emplacement of TTG gneisses and potassic granitoids in the Nyabessane granite-greenstone terranes, NW Congo Craton (southern Cameroon): Zircon U[sbnd]Pb geochronology, petrogenesis and tectonic implications

Archean granitoids played key roles in the generation and differentiation of the Archean continental crust and provide clues to understand crustal processes in the early Earth. Abundant Mesoarchean granitoids were emplaced in the Nyabessane granite-greenstone terrane (NGB), part of the Ntem Complex of the Northwest Congo Craton. They include charnockites, tonalite-trondhjemite-granodiorite (TTG), granitic and monzogranitic gneisses. Here, we present a geochemical and geochronological (zircon LA-ICP-SF-MS UPb) study of these granitoids to determine their petrogenesis and to better constrain the crustal evolution of the Ntem Complex. Field and petrographic observations indicate that most of these granitoids underwent extensive metamorphism and deformations, associated with anatexis. Zircon UPb dating results suggest that the charnockite, TTGs and granitic gneisses, and monzogranites have emplacement ages of 2910 ± 11 Ma, 2870–2865 Ma and 2852 ± 31 Ma, respectively. The charnockites have low SiO2 (55–58 wt%) and high Al2O3 (16–18 wt%), CaO (7–8 wt%) and MgO (∼ 4.5 wt%) content with Mg# ∼ 54, and exhibit magnesian, metaluminous characteristics of the Cordilleran granitoid-type formed in magmatic arc. The 2.87–2.86 Ga TTG gneisses are silica-rich (55–58 wt% SiO2), sodic (3–5 wt% Na2O, Na2O/K2O = 1–3), with HREE-depleted, and display the typical Archean medium- to low pressure TTG geochemical features groups. Their chemical compositions are characteristics of TTG-like melts derived from the partial melting of hydrated low- to high-K metabasic/thickened lower crust at various depths followed by magmatic differentiation during ascent. When compared to the TTG gneisses in the NGB, the ∼2.87 Ga granitic gneisses are K-rich, and high Gd/Yb, Th/Yb, Th/Nb, Sr/Y and La/Yb ratios but lower MgO, Yb, V, Y, Cr, Ni and Sr contents, matching typical Archean hybrid and potassic granitic rocks. We propose that the granitic gneisses were derived from the intra-crustal melting of a pre-existing felsic crust. The granitic and the TTG gneisses were generated contemporaneously through the same magmatic event at ∼2.87–2.86 Ga. The ∼2852 Ma monzogranitic gneisses are ferroan and metaluminous rocks, and show LREE enrichment with strongly fractionated REE patterns and positive Eu anomalies. Geochemical features, together with the presence of ∼2.9 Ga-old inherited zircon grains are consistent with the remelting of Mesoarchean granitoids. Considering the petrogenetic, regional geological and geochronological data, the Mesoarchean granitoid magmatism of the Ntem Complex was likely generated via complex transitional geodynamic regimes involving subduction and accretion processes.

A zero-emission collaborative treatment method for brown corundum fly ash and carbide slag: Producing silicon fertilizer while recovering gallium and potassium

Brown corundum fly ash (BCFA) is a fine dust generated during the smelting process of brown corundum. It is rich in gallium and potassium, and improper handling can cause severe environmental damage. This study proposes a cyclic process of calcification leaching, carbonation precipitation, and lye regeneration for the collaborative treatment of BCFA and carbide slag. The leaching efficiencies of gallium and potassium were determined to be 94.02 % and 85.32 %, respectively, under the optimized conditions (120 min, 180 °C, Ca/Si molar ratio 0.9, KOH 10 g/L) of calcification leaching. The contents of effective SiO2 and CaO in the silicon fertilizer were measured at 34.71 wt% and 33.02 wt%, respectively. During the carbonation precipitation process, gallium and aluminum were extracted from the filtrate and achieved respective contents of 2.1429 wt% and 32.99 wt% in the resulting coprecipitate. The carbonated lye was regenerated through a causticization reaction, and after four cycles, the regenerated lye maintained a consistently high leaching efficiency for gallium and potassium. This method achieves the comprehensive utilization of BCFA and carbide slag without generating any waste residue or wastewater. Additionally, it provides a novel approach for the collaborative treatment of similar solid wastes.

Geochemical variations of anatectic melts in response to changes of P–T–H2O conditions: Implication for the relationship between dehydration and hydration melting in the Himalayan orogen

The anatectic mechanism is the most fundamental criterion in determining the petrogenetic relationship between migmatite, granulite and granite at convergent plate margins. Although two main anatectic mechanisms, namely water-absent (dehydration) and water-fluxed (hydration) melting, have been identified in many collisional orogens, their spatiotemporal relationship and genetic connection remain obscure. To address this issue, we conduct an integrated study of forward phase equilibrium and trace element modelling for partial melting of metapelite in the Himalayan orogen. The results are used to decipher changes of phase relation and melt composition in response to changes of temperature, pressure and water content. Pressure and water content mainly affect the solidus and evolving residual mineral assemblages, whereas temperature controls the anatectic reaction. Hydration melting at lower pressure and temperature would produce anatectic melts with relatively high SiO2, FeOT + MgO, CaO, K2O, and Ba contents and SiO2/Al2O3 ratios, but low Al2O3 and Na2O contents and Na2O/K2O and Rb/Sr ratios. In contrast, dehydration melting at higher pressure and temperature would generate anatectic melts with relatively high Al2O3 and Na2O contents and Na2O/K2O and Rb/Sr ratios, but low SiO2, FeOT + MgO, CaO, K2O, and Ba contents and SiO2/Al2O3 ratios. A comparison of geochemical compositions between the modelled melts and the two groups of well-characterized leucogranites in the Himalayan orogen indicates that the coeval dehydration and hydration melting would likely occur at the deeper and shallower crustal levels, respectively. In combination with the secular evolution of metamorphic facies series in the Himalayan orogen, we propose a spatiotemporally coupled dehydration-hydration melting mechanism. The early metamorphism at lower geothermal gradients would result in metamorphic dehydration in the lower crust and hydration in the upper crust during the syn-collisional period in the Early Cenozoic. As a result, the later metamorphism at higher geothermal gradients would lead to dehydration melting in the lower crust and hydration melting in the upper crust during the post-collisional period in the Late Cenozoic. This study highlights the applicability of phase equilibrium and trace element modelling to reveal the geochemical variations of anatectic melts in response to changes of P–T–H2O conditions. This provides new insights into the relationship between dehydration and hydration melting in collisional orogens.

Effect of oxide interactions on chromium speciation transformation during simulated municipal solid waste incineration

Chromium released during municipal solid waste incineration (MSWI) is toxic and carcinogenic. The removal of chromium from simulated MSWI flue gas by four sorbents (CaO, bamboo charcoal (BC), powdered activated carbon (PAC), and Al2O3) and the effects of four oxides (SiO2, Al2O3, Fe2O3, and CaO) on chromium speciation transformation were investigated. The results showed that the removal rates of total Cr by the four sorbents were Al2O3 < CaO < PAC < BC, while the removal rates of Cr(VI) by the four sorbents were Al2O3 < PAC < BC < CaO. CaO had a strong oxidizing effect on Cr(III), while BC and PAC had a better-reducing effect on Cr(VI). SiO2 was better for the reduction of Na2CrO4 and K2CrO4 above 1000°C due to its strong acidity, and the addition of CaO significantly inhibited the reduction of Cr(VI). MgCrO4 decomposed above 700°C to form MgCr2O4, and the reaction between MgCrO4 and oxides also existed in the form of a more stable trivalent spinel. Furthermore, when investigating the effect of oxides on the oxidation of Cr(III) in CrCl3, it was discovered that CaO promoted the conversion of Cr(III) to Cr(VI), while the presence of chlorine caused chromium to exist in the form of Cr(V), and increasing the content of CaO and extending the heating time facilitated the oxidation of Cr(III). In addition, silicate, aluminate, and ferrite were generated after the addition of SiO2, Al2O3, and Fe2O3, which reduced the alkalinity of CaO and had an important role in inhibiting the oxidation of Cr(III). The acidic oxides can not only promote the reduction of Cr(VI) but also have an inhibitory effect on the oxidation of Cr(III) ascribed to alkali metals/alkaline earth metals, and the proportion of acidic oxides can be increased moderately to reduce the generation of harmful substances in the hazardous solid waste heat treatment.

Steam oxidation performance of Yb2Si2O7 environmental barrier coatings exposed to CMAS

Environmental barrier coatings (EBCs) are necessary for use of SiC/SiC ceramic matrix composites (CMCs) in gas turbine engines. Due to the complex operational environments, it is increasingly important to understand the interplay of damage modes to project the durability of the EBC/CMC system. Two life-limiting failure mechanisms of EBCs are steam oxidation and molten calcium-magnesium-aluminosilicate (CMAS) attack. Steam oxidation results in the formation of a thermally grown oxide (TGO) that acts as a weak interface and CMAS/EBC interactions cause thermomechanical and thermochemical changes that compromise coating integrity. EBCs consisting of a Yb2Si2O7 topcoat and a silicon bond coat were subjected to low (2 mg/cm2) loadings of two CMAS compositions prior to steam oxidation at 1316 °C for up to 300 h. Exposure to CMAS reduced the TGO thickness and the low CaO content glass resulted in the thinnest oxide scales. However, glass exposure had mechanical consequences that caused premature coating delamination.

Influence of chemical constituents of binder and activator in predicting compressive strength of fly ash-based geopolymer concrete using firefly-optimized hybrid ensemble machine learning model

This study focuses on investigating the impact of chemical constituents in binders and activators on the prediction of strength, particularly proposing a novel hybrid ensemble model that synergizes the strengths of three base models optimized using the Firefly Algorithm. The primary objective is to enhance the accuracy of predicting the compressive strength (CS) of fly ash-based (FA) geopolymer concrete (GPC). The dataset employed encompasses comprehensive material and chemical information, facilitating a predictive approach linking factors to strength. Rigorous preprocessing techniques are employed to eliminate outliers and ensure data integrity. Multivariate analyses are executed to visually represent the dataset's structure. The development of the hybrid ensemble model is realized through a stacking strategy, integrating the predictive capabilities of individual models. Thorough evaluation using diverse statistical metrics validates the superiority of the hybrid model compared to standalone base models, underscoring its enhanced precision in CS prediction for FA-based GPC. Sobol and FAST global sensitivity analysis was also employed to find the influence of input parameters on strength. Extra water content and curing temperature with Sobol indices of 67.2% and 42.5%, and FAST indices of 65.2% and 45% were found to be the most sensitive parameters of the studied database. Among the chemical constituents of binders and activators, the SiO2 content and CaO content of FA exhibited greater sensitivity, impacting the CS. On the other hand, the Na2O, Al2O3, and Fe2O3 content of fly ash and the SiO2 and Na2O percentage of sodium silicate were found to have a relatively lower impact.

Characteristics of Fly Ash as a Constituent Material for Geopolymer

Fly ash waste from the Asam-Asam Power Plant in South Kalimantan continues to increase. Various attempts have been made to utilize fly ash waste, among others. as a basic material for making geopolymers. Geopolymer is environmentally friendly because it replaces all cement with high Silica (Si) and Alumina (Al) wastes such as fly ash. This study aims to characterize fly ash as a raw material of geopolymer. Fly ash was filtered using 200 mesh and then heated in an oven at 105°C for 24 hours. The prepared fly ash was then tested for physical properties and compound analysis using XRF, identification of chemical bonds and functional groups using FTIR, morphology, and elements using SEM EDX. Initial and final setting time was investigated using the Vicat apparatus to determine e whether cement is undergoing proper hydration. The results indicated that the fly ash was classified to class F. That was based on the amount of SiO2 + Al2O3 + Fe2O3 of 85.91%, and the CaO content was less than 10%. Moreover, fly ash’s initial and final setting time was 1072.5 and 3180 minutes, respectively. Fly ash in this research can be used as a raw material for geopolymers.

Studying the influence of cement type on the strength development and microstructure formation of filling material produced from dredged mud in urban pond/lake dredging in Hanoi City

There are many countries in the world have recycled dredged mud as filling material. In Vietnam, some studies show that dredged mud can be recycled as filling material from cement PCB. This study is aimed at discussing the effect of chemical composition in cement on strength and microstructure of filling material (VSL material). A series of laboratory tests for evaluating the influence of chemical composition in cement such as: CaO, SO3, Al2O3 to strength of VSL material. In the tests, the main materials are West Lake mud, PCB cement and polymer with different ratios. The results show that soil strength is inversely proportional to CaO content and directly proportional to Al2O3, SO3 content. Moreover, the Scanning electron microscopy–SEM test evaluated the influence of cement and polymer to change in the microstructure of VSL material.

An Investigation of the Chemical Composition of Bottom Sediments from Dried Lake Gavur of Türkiye by Using XRF and Multivariate Data Analysis

Lake sediments offer valuable information about the geographical, climatic and environmental changes. This work examined the chemical elements of eleven sediment samples from the old bottom (0-5m; 0.5m increments) of the dried Lake Gavur in Türkiye by applying XRF along with PCA and PLSR data analyses. The highest but negative correlations were observed for Sr (-0.89), S+SO3 (-0.74) and Zr+ZrO2 (-0.61) with sampling depths meaning that their concentrations were lower in deeper locations (4.0-5.0 m). In contrast, Ti+TiO2 (0.60), Al+Al2O3 (0.53) and Cu+CuO (0.51) had high and positive correlations and their quantities increased as the depth increased. The age of two samples was determined as 4752±33 BP years (2.5 m) and 5470±35 BP (5.0 m). Ca+CaO content was found as lower and Ti+TiO was higher in the deeper sediment (5.0 m) indicating rainy periods. PCA clustered the samples into two groups as deeper samples (4.0-5.0 m) and other samples (0.0-3.5m) while PLSR grouped them into three clusters as deeper (4.0-5.0 m), medium-depth (1.5-3.5 m) and shallower (0.0-1.0m) samples. PLSR model had a good performance to estimate the sampling depth from the chemical elements (R2cal=0.95; R2val=0.67) which means that the variations of the chemicals were highly dependent on the sampling depth.

Impact of CaO addition on physico-chemical properties, crystallization, chemical durability and in vitro behavior of Na2O-ZnO-TiO2-P2O5 glasses

This work investigates the effect of CaO addition on physico-chemical properties, crystallization, chemical durability and bioactivity of phosphate-based glasses. To this end, five glass compositions in the system (40-x)Na2O-xCaO-10ZnO-20TiO2-30P2O5 with x = 0, 5, 10, 15 and 20 mol % have been elaborated by the conventional melt-quenching technique. Replacing Na2O with CaO oxide in the studied glasses increased remarkably the glass transition temperature Tg and density (ρ), while VM decreased with increasing CaO content indicating the high strength in the glass network. The existence of PO3 and PO4 units with P-O-P and P-O-Ti linkages in the glassy network was revealed by Infrared spectroscopy. The chemical durability was improved with increasing calcium content, indicating that replacing Na-O bonds with more covalent and stronger Ca-O bonds strengthen and crosslink the glassy network. The in vitro bioactivity of the two glass samples (x = 0 and 15 mol %) was studied using SBF solution. XRD, Infrared, ICP, and pH measurements proved the formation of a hydroxyapatite layer on the glass surface after interaction with the SBF medium, which is a crucial property of a potential bioactive glass. The correlation between XRD, Infrared, and ICP techniques indicated that glass containing calcium is more bioactive than free-calcium glass.

Triangulation Method for Limestone Estimation in CV. Atang Village, Jemparing: Insights from Long Ikis, Paser District, East Kalimantan

The Atang Are Abadi Firm is a limestone mining company that has carried out further exploration activities to determine the volume, density, and continuity of grades in the exploration area. The exploration activities conducted core drilling at 17 drilling points, a distance of less than 250 meters, and an area of 19.36 ha. This research determined the geological domain of limestone layers with parameters of CaO content greater than 53% through a triangulation (triangle) method. Meanwhile, the cut-and-fill method was used for resource and reserve calculations. The resource acquisition in limestone layers with a content of more than 53% reached 25,682,831.9 BCM, and the acquisition of reserves in limestone layers with a content of more than 53% had 6,788,073.56 BCM. The estimation results of limestone resources and reserves obtained based on the Indonesian National Standard 4726: 2019 are included in the classification of measured limestone resources and proven limestone reserves.