Addition Of CaCO3 Research Articles

Screening of acid-tolerant hybrid Corn lines and parents using modified acid mineral soil

Screening of hybrid corn parent lines quickly and cheaply compared to hydroponic methods in the laboratory is needed to support the assembly of new high yielding varieties of acid tolerant corn. Addition of CaCO3 as equivalent to 2 t/ha (normal soil), while 0.5 t/ha AlCl3 (acidic). A total of 12 elite maize lines were tested based on relative root growth (RRG). Four sets of experiments were made, namely 2 sets normal soil media (pH 6.5) and 2 sets acid soil media (pH 4.3). Experimental design used in each experimental set was a randomized block with three replications. Results showed that rapid screening of hybrid maize parental lines could be carried out using modified soil acidity method by adding CaCO3 and AlCl3 to acid soil by measuring relative root growth (RRG) as the main variable. Corn obtained by genotypes No.80, MAL03x192, and Bisi-18 were classified as tolerant, MAL03x28, MAL03x182, MAL03x42, MAL03x44, MAL03x107, MAL03x115 were classified as moderately tolerant, while MAL03x100, MAL03x56, classified as sensitive. Screening of hybrid parent lines on acid soil modified to pH 4.3 (acidic) and normal pH 6.5 at seedling age 7 days after planting (dap) was more accurate than at seedling age of maize 14 dap.

Assessment of eggshell and CaCO3 reinforced recycled aluminium green metal matrix

In this study, an environmentally friendly metal matrix was prepared, and the influence of eggshell powder and CaCO3 particles on the tensile strength and hardness of recycled aluminium were assessed.A matrix made of recycled aluminium was employed. Calcium carbonate and eggshells served as the study's reinforcing materials. Separately, weight percentages of 2, 4, and 8% of eggshell and calcium carbonate were used. The samples were made by sand-casting.The results showed that both eggshell and calcium carbonate positively affect the hardness, yield, and ultimate tensile strength of recycled aluminium. The hardness values were improved as the percentage of the eggshell increased. The maximum hardness was achieved at 2% calcium carbonate. Similarly, the highest improvement of yield strength was for 2% CaCO3 addition, while the highest tensile strength was obtained at 8% eggshell addition.To get better results, it would be desirable to use finer eggshells than those utilized in this study.Composites made with an aluminium matrix exhibit exceptional mechanical and physical characteristics. The most challenging obstacle to overcome is the cost of metal matrix composites. Eggshells are a by-product that could be employed as a lightweight, affordable form of reinforcement. One way to get rid of this by-product, improve composite characteristics, and lower the cost of aluminium composite is to use eggshells.A comparative investigation was carried out to determine the effects of adding agricultural by-product eggshell, and commercial CaCO3 reinforcement material on the characteristics of recycled aluminium matrix integrated 425 m sized eggshell and CaCO3 separately as a reinforcement material to create a metal matrix that is beneficial to the environment.

Research on Properties of PBAT/CaCO3 Composite Films Modified with Titanate Coupling Agent.

High cost, low crystallinity, and low-melt strength limit the market application of the biodegradable material poly (butylene adipate-co-terephthalate) (PBAT), which has become a major obstacle to the promotion of PBAT products. Herein, with PBAT as resin matrix and calcium carbonate (CaCO3) as filler, PBAT/CaCO3 composite films were designed and prepared with a twin-screw extruder and single-screw extrusion blow-molding machine designed, and the effects of particle size (1250 mesh, 2000 mesh), particle content (0-36%) and titanate coupling agent (TC) surface modification of CaCO3 on the properties of PBAT/CaCO3 composite film were investigated. The results showed that the size and content of CaCO3 particles had a significant effect on the tensile properties of the composites. The addition of unmodified CaCO3 decreased the tensile properties of the composites by more than 30%. TC-modified CaCO3 improved the overall performance of PBAT/CaCO3 composite films. The thermal analysis showed that the addition of titanate coupling agent 201 (TC-2) increased the decomposition temperature of CaCO3 from 533.9 °C to 566.1 °C, thereby enhancing the thermal stability of the material. Due to the heterogeneous nucleation of CaCO3, the addition of modified CaCO3 raised the crystallization temperature of the film from 97.51 °C to 99.67 °C and increased the degree of crystallization from 7.09% to 14.83%. The tensile property test results showed that the film reached the maximum tensile strength of 20.55 MPa with the addition of TC-2 at 1%. The results of contact angle, water absorption, and water vapor transmission performance tests showed that TC-2 modified CaCO3 increased the water contact angle of the composite film from 85.7° to 94.6° and decreased the water absorption from 13% to 1%. When the additional amount of TC-2 was 1%, the water vapor transmission rate of the composites was reduced by 27.99%, and the water vapor permeability coefficient was reduced by 43.19%.

Microbiological passive treatment of Mn/Zn-containing mine water

The Mn/Zn-containing black sediments were formed at the closed N-mine site and used as a common inoculant to set up two different laboratory-scale passive bioprocesses (named Tank-I and Tank-II) to treat mine waters containing 70 mg/L Mn2+ and < 1.8 mg/L Zn2+. Using CO32−-free synthetic mine water, Tank-I (a natural zeolite down-flow tank with surface aeration) achieved >97% Mn2+ and > 80% Zn2+ removal at an hydraulic retention time (HRT) of 15–17 h, while Tank-II (an up-flow tank filled with semi-calcined dolomite with a bottom aeration) removed >87% Mn and > 79% Zn at an HRT of 24 h. Further shortening of the HRT resulted in a rapid decline in performance (Zn2+ desorption followed by Mn2+ elution) in both tanks. As the semi-calcined dolomite in Tank-II had been passivated and deactivated during the pre-run period, periodic CaCO3 addition (plus HRT readjustment) was required in both tanks to reverse this performance degradation. Treatment of the real mine water was generally faster and more complete, presumably due to the continuous influx of naturally occurring CO32− into the system. This allowed for >99% Mn/Zn removal at HRT 8–15 h in Tank-I and at HRT 17 h in Tank-II. In Tank-I, birnessite was formed as a result of the oxidative removal of Mn2+ where the Mn average oxidation state (AOS) progressed from 3.53 to 3.85 through the activity of potential Mn-oxidizing genera such as Bacillus, Pseudonocardia, Brevibacillus, Nitrospira, Methylobacterium, Bosea, Leptothrix, Mycobacterium, Rhizobium and Pseudomonas. While in Tank-II, in addition to abiotic Mn removal by semi-calcined dolomite in the early stages, microbial Mn oxidation activity developed over time to produce woodruffite and birnessite, with Mn AOS progressing from 3.53 to 3.79 through the activity of potential Mn-oxidizing genera such as Methylobacterium and Leptothrix. The microbial community developed very differently between the two tanks, due to the different tank designs. Off-site Pseudomonas SK3 cells co-inoculated only in Tank-I were eliminated by the indigenous community, presumably due to the lack of Zn2+ tolerance. Both tanks were effective in treating the target mine water to meet the effluent standard while producing equally stable Mn oxides. Although the two tanks cannot be directly compared in detail due to their completely different designs, the simpler Tank-I design was superior overall in terms of speed and microbial activity and diversity.

Fire Resistance Test of Geopolymer Coatings on Non-Metallic Underlying Substrates

This article summarizes the results from the fire resistance test of geopolymer suspensions in the form of coatings on non-metallic substrates. Their heat resistance was evaluated based on the burn-through time compared to the uncoated substrate. Non-metallic substrate materials, extruded polystyrene (XPS) and chipboard (DTD) were chosen as the underlying substrates for GP suspension research. Parameters from the fire resistance test as fire test duration of geopolymer coatings and percentage increase in burn time of geopolymer coatings on an XPS and DTD substrates compared to an uncoated substrate were evaluated. One of the discussed point was also the addition of CaCO3 and Al(OH)3 for studding flame retardancy effect.

Influence of Calcium Carbonate Concentration on the Properties of Polypropylene Stretched Flat Tapes Used in Raffia Packaging

The production of stretched polypropylene (PP) tapes for packaging has recently led to advancements in raffia packaging, which has improved multiple technical characteristics. In addition to the beneficial economic impact, this packaging is more sustainable. The present work evaluated the properties of stretch tapes obtained with different concentrations of calcium carbonate (CaCO3) to reduce the cost of production of raffia packaging. We produced the tapes in an industrial environment using a single-screw extruder with a flat die containing 3, 7, 10, 15, 17, and 20 wt % of CaCO3. The tensile strength, elongation, and toughness of the tapes were evaluated. Tensile strength and toughness increase with the addition of CaCO3 while the elongation decreases. Stearic acid (CH3(CH2)16COOH) in the filler contributed positively to the dispersion and distribution of the filler in the matrix, preserving the mechanical properties. The results showed that incorporating CaCO3 in flat strips stretched from PP emerges as an alternative for cost reduction with raw material for raffia packaging.

Construction of a multi-scale microporous structure in EVA matrix toward passive cooling roofs

Global warming has brought tremendous attention to developing passive cooling materials. Due to the high performance of solar reflection, heat insulation and infrared radiation, constructing porous structures in polymeric matrix has emerged as a promising technique to fabricate passive cooling materials. This work herein demonstrated a multi-scale microporous structure in ethylene-vinyl acetate copolymer (EVA) matrix via chemical foaming and chemical etching. It was found that pore size and shape depended upon the addition and removal of inorganic particles CaCO3. In chemical foaming system, by reflecting 76.9% NIR light and transmitting heat through the atmosphere in the long-wave infrared, the cellular EVA/CaCO3 composites (40% porosity, 13.84 μm avg. pore size)-covered device exhibited a final temperature of 31.6 °C after solar simulation for 1 h with the intensity of ∼594 W/m2. To further enhance the cooling effect, the CaCO3 particles in cellular EVA/CaCO3 composites were removed via 20% HCl solution etching to minimize the pore structure. Higher heat insulation with thermal conductivity of 0.148 Wm−1K−1 accompanied by 65.5% NIR irradiance and 0.84 thermal emittance made the excellent cooling property with a final temperature of 30.6 °C (lower than all EVA/CaCO3 composites-covered device) realize after chemical etching. Furthermore, the prepared porous EVA materials possessed good tensile properties and are of potential value in the field of passively cooled roofs.

Positive effect of Ca addition on the risk of Cu and Zn in digestate as biofertilizer

The addition of Ca in anaerobic digestion will passivate the heavy metals in digestate. The effects of CaCl2, Ca(OH)2 and CaCO3 addition on the anaerobic digestion process and the speciation changes of Cu and Zn in solid fraction of anaerobic digestate (SFD) after digestion were studied. Then the effects of Ca-containing solid fraction digestate (SFD-Ca) application on the speciation changes of Cu and Zn in soil and the effects of ryegrass on the enrichment of Cu and Zn were also explored through pot experiments. The results indicated that: The addition of Ca(OH)2 was beneficial to the transfer of Cu and Zn from the liquid fraction of anaerobic digestate (LFD) to SFD, and the transfer effect was the best. The transfer amount of Cu and Zn increased by about 10.0% and 4.2%, respectively, compared with the blank group. The SFD-Ca promoted the increase of biomass, inhibited the enrichment of Cu and Zn by ryegrass, and the effect of a high concentration of Ca(OH)2 was the best. Ryegrass biomass increased by 19.7%, and the enrichment of Cu and Zn decreased by 39.3% and 31.1%, respectively. High concentration of Ca(OH)2-containing solid fraction digestate (SFD-Ca(OH)2) had the best passivation effect on Cu and Zn in soil, the residual state of Cu and Zn in soil increased by 4.3% and 7.8%, respectively. Adding a high concentration of Ca(OH)2 had a positive effect on ryegrass biomass and reduced the risk of Cu and Zn when SFD was used as biofertilizer.

Conversion of CO2 and Its Utilization in the Preparation of Cement-Slag-CaCO3 Ternary Blends

A reduction in CO2 emissions is necessary in the concrete industry. This study proposes a CO2 conversion technique by which CO2 gas is converted into solid nano CaCO3 and used to replace the partial binder of cement-slag blends in ratios of 2%, 4%, and 6%. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analyses confirmed the formation of hemicarboaluminate (Hc) and monocarboaluminate (Mc) due to the chemical reaction between nano CaCO3 and the Al2O3 phase in the binder. XRD analysis revealed that at 28 days, the addition of nano CaCO3 can inhibit the transformation of ettringite (AFt) to monosulfate (AFm). As the contents of nano CaCO3 increased, the hydration heat, strength, ultrasonic pulse velocity (UPV), electrical resistivity, and combined water content increased. The degree of increment of the electrical resistivity was more pronounced than that of the strength. For various specimens, the strength and combined water content presented a linear relationship, and the strength and UPV presented an exponential function. The reduction rate of normalized CO2 emissions (the ratio of CO2 emissions of the paste to its strength) was much higher than the replacement percentage of nano CaCO3. This was because nano CaCO3 increased the late strength and had a negative CO2 emission value.

Addition of Calcium Carbonate (CaCO3) and Magnesium Sulfate (MgSO4) to Vannamei Shrimp (Litopenaeus vannamei) Rearing Media in Fresh Water

Vannamei shrimp cultivation in freshwater media is still not optimal. Scabra et al., 2022 stated that the growth of vannamei shrimp reared on media supplemented with CaCO3 was higher than that reared on media without the addition of CaCO. However, it is still lower than the vannamei shrimp reared in seawater media. The addition of other types of minerals is needed to complement CaCO3 in supporting growth. The purpose of this study was to determine the effect of rearing vaname shrimp on low-salinity media with the addition of CaCO3 and MgSO4 ratios with different doses. The treatment in the study was the addition of CaCO3 : MgSO4 with different ratios, namely 40:0 (P2), 40:20 (P3), 40:40 (P4), and 40:60 (P5). A treatment was also applied which was a positive control, namely the rearing of vannamei shrimp in seawater media (P1). The results showed that the best specific growth values were P1 (3.83%), P4 (3.64%), P5 (3.5%), P3 (3.46%), and P2 (3.42%) ). In fresh water rearing, P4 was the best treatment which resulted in a survival rate of 77%, a specific weight growth rate of 3.64%, and a specific length growth rate of 2.14%. Shrimp growth in fresh water media is still not as high as maintenance in seawater media. Therefore, it is still necessary to add other types of minerals that can support growth.

Enhanced recovery of phosphorus in sewage sludge-derived biochar with CaCO3: Phosphorus speciation and slow-release phosphorus behavior

The recovery of phosphorus (P) from sewage sludge through pyrolysis is one of the most promising alternatives to alleviate the shortage of P supply in the future. Adding calcium additives is beneficial to the conversion of available P and helps to improve the recovery and utilization efficiency of P in biochar. This study thoroughly examined the influence of CaCO3 on the speciation and slow-release behavior of P in sludge during pyrolysis at 500 and 700 °C. The addition of CaCO3 could enhance the conversion of non-apatite inorganic phosphorus (NAIP) into more accessible apatite phosphorus (AP). We observed that adding CaCO3 (2.5–20 %) to raw sludge at 500 °C increased the proportion of AP in inorganic phosphorus (IP) from 65.2 to 97.3 % but did not increase the concentration of AP, which remained between 31.03 and 31.64 mg/g. At 700 °C, introducing CaCO3 (2.5–20 %) boosted the AP content from 35.08 to 41.38 mg/g and increased the proportion of AP in IP from 67.7 to 98.6 %. Moreover, irrespective of the pyrolysis temperature being 500 °C or 700 °C, the final main form of P in biochar with CaCO3 was Ca5(PO4)3OH, according to experimental characterization results (X-ray photoelectron spectroscopy and X-ray diffraction) and thermochemical calculations. Additionally, the efficacy of citric acid (CA) in releasing biochar-bearing P was tested in a laboratory extraction experiment for 21 days. CaCO3-amended biochar showed a significantly slower total phosphorus (TP) release than the biochar without CaCO3 daily, and the amount of TP decreased with increasing amounts of added CaCO3. The finding of this study indicates that biochar generated by adding 10 % CaCO3 has the highest AP concentration (41.38 mg/g) at 700 °C, and its TP-release efficiency in CA is 0.29–1.98 mg/g in 21 days, which shows remarkable potential as a soil fertilizer with slow P release.

Phase Morphology, Mechanical, and Thermal Properties of Calcium Carbonate-Reinforced Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) Bioplastics

Poly(L-lactide) (PLLA) is a promising candidate as a bioplastic because of its non-toxicity and biodegradability. However, the low flexibility of PLLA limits its use in many applications. Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) (PLLA-b-PEG-b-PLLA) block copolymer is of interest for bioplastic applications due to its superior flexibility compared to PLLA. The aim of this work is to modify PLLA-b-PEG-b-PLLA using a low-cost calcium carbonate (CaCO3) filler to improve material properties compared to PLLA/CaCO3 composites. The addition of CaCO3 enhanced the crystallinity and thermal stability for the PLLA-b-PEG-b-PLLA matrix but not for the PLLA matrix, as determined by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). Phase morphology investigation using scanning electron microscopy (SEM) revealed that the interfacial adhesion between PLLA-b-PEG-b-PLLA and CaCO3 was stronger than between PLLA and CaCO3. Additionally, tensile testing was carried out to determine the mechanical properties of the composites. With the addition of CaCO3, the tensile stress and Young's modulus of the PLLA-b-PEG-b-PLLA matrix were increased, whereas these properties of the PLLA matrix were significantly decreased. Thus, CaCO3 shows great promise as an inexpensive filler that can induce nucleation and reinforcing effects for PLLA-b-PEG-b-PLLA bioplastics.

Impacts of coexisting mineral on crystallinity and stability of Fe(II) oxidation products: Implications for neutralization treatment of acid mine drainage.

The neutralization treatment of acid mine drainage involves the oxidation of Fe(II), but little is known about the effects of co-existing minerals on the oxidation and hydrolysis of Fe(II) to iron oxides. Here we investigated the transformation of fresh and heated Fe(II) oxidation coprecipitates, which were synthesized in the presence and the absence of five co-existing minerals (montmorillonite, kaolin, quartz (SiO2), aluminium oxide (Al2O3) and calcium carbonate (CaCO3)). In the FeSO4 system with montmorillonite or kaolin, the formation of lepidocrocite was inhibited with the increase of clay mineral contents. In the same system, heated coprecipitates of montmorillonite were mainly comprised of amorphous ferrihydrite and its transformation was retarded by the excess montmorillonite. In the FeCl2 system with SiO2, Al2O3 or CaCO3, akaganeite formation was inhibited with the increase in the corresponding mineral contents. In the same system, goethite formation was blocked by either CaCO3 or Al2O3 and the growth of lepidocrocite was inhibited by CaCO3 or SiO2. However, magnetite formation was enhanced by addition of CaCO3. These findings are important for predicting products of abiotic Fe(II) oxidation during the neutralization of acid mine drainage and for better understanding the transformation of amorphous iron oxides in the complicated environmental matrix.

The interfacial behaviors of different arsenic species on polyethylene mulching film microplastics: Roles of the plastic additives.

Plastic additives widely existed in plastic mulching films, but their roles in microplastics (MPs) derived from these plastics as vectors of pollutants were not clear. This work clarified the role of plastic additives on the sorption-desorption behaviors of four arsenic species (arsenite (As(Ⅲ)), arsenate (As(Ⅴ)), roxarsone (ROX), and p-arsanilic acid (p-ASA)) on/from virgin polyethylene (V-PE), white PE mulching film (W-PE, with Si-containing additives), and black PE mulching film (B-PE, with CaCO3 and TiO2 additives) MPs. The maximum sorption amounts of arsenic species on V-PE (3.33-20.10mg/kg) and W-PE MPs (4.78-21.93mg/kg) had no significant difference, while those on B-PE (43.02-252.19mg/kg) facilitated by its additives were up to one order of magnitude greater than V-PE or W-PE (p<0.05). Desorption hysteresis index (HI) indicated the irreversible arsenic sorption on three PE MPs, especially for B-PE containing additives that can co-precipitate and complex with arsenicals. The effects of pH, humic substances, and coexisting anions on arsenic sorption by B-PE were more obvious than that by V-PE or W-PE MPs, attributing to electrostatic interaction enhanced by CaCO3 and TiO2 additives. This work provides theoretical basis for migration of arsenic species on MPs containing plastic additives and their potential environmental risk assessment.

Microbial production of stereospecific lactic acid from sugarcane trash hydrolysate with no pre-detoxification step

Sugarcane trash (SCT) is a promising underused lignocellulosic material for the production of chemicals in biorefineries. In this work, we studied the use of SCT to produce lactic acid (LA), an important commodity chemical used in food and bioplastic industries. SCT was pretreated with a hydrothermal liquid hot water step followed by saccharification with Cellic® CTec2, which resulted in the SCT hydrolysate containing 30.42±0.08 g/L total sugar, equivalent to 88.10% and 42.92% glucose and xylose recoveries, respectively. Screening of stereospecific LA production exhibited Lactococcus lactis BCC 68868 and Leuconostoc lactis BCC 62792 efficiently utilized SCT hydrolysate converted to entirely L-LA and D-LA, respectively. A detoxification step was unnecessary for hydrolysate fermentation to LA, and the addition of CaCO3 for pH control enabled complete hydrolysate utilization. La. lactis BCC 68868 converted SCT hydrolysate into optically pure L-LA at 19.34 g/L, equivalent to a conversion yield of 0.95 g LA/g sugar. While Le. lactis BCC 62792 produced D-LA at 10.39 g/L, equivalent to a conversion yield of 0.45 g LA/g sugar with ethanol and acetic acid as the by-products, suggesting their homofermentative and heterofermentative characteristic, respectively. This work demonstrates a promising strategy to produce enantiomerically defined LA from this underutilized agricultural waste.

CHARACTERIZATION OF BIODEGRADABLE FOAMS OBTAINED FROM CASSAVA STARCH WITH THE ADDITION OF SOY PROTEIN AND CaCo3 AS BLOWING AGENT

Compostable foodservice packaging is arguably the biggest trend in the industry right now because it is an alternative that ecologically-correct. The purpose of this study is to determine the effect of soy protein and calcium carbonate (CaCO3) addition on mechanical properties, biodegradability, water absorption ability and morphological structure of biodegradable foam made from cassava starch. The addition of calcium carbonate (CaCO3) as blowing agent and pure protein isolate with different variables have an effect on biodegradable foam quality. The amount of calcium carbonate (CaCO3) addition was varied from 0; 2.8; 5.6; 8.3; 11.1% w/w, while the pure soy protein isolate was varied from 0, 15, 20, 25, 30% w/w. The best result of biodegradable foam was obtained at 30.0% of protein and 11.1% of CaCO3 addition which produce 24.09% absorption ability, 28.67% degradability, and 9.2 MPa tensile strength. At higher levels of protein and calcium carbonate (CaCO3) addition, the product of biodegradable foam be more water absorbent, easily degraded, has lower tensile strength, and has an irregular wall cell structure

Ca Minerals and Oral Bioavailability of Pb, Cd, and As from Indoor Dust in Mice: Mechanisms and Health Implications.

Elevating dietary calcium (Ca) intake can reduce metal(loid)oral bioavailability. However, the ability of a range of Ca minerals to reduce oral bioavailability of lead (Pb), cadmium (Cd), and arsenic (As) from indoor dust remains unclear. This study evaluated the ability of Ca minerals to reduce Pb, Cd, and As oral bioavailability from indoor dust and associated mechanisms. A mouse bioassay was conducted to assess Pb, Cd, and As relative bioavailability (RBA) in three indoor dust samples, which were amended into mouse chow without and with addition of , , Ca gluconate, Ca lactate, Ca aspartate, and Ca citrate at . The mRNA expression of Ca and phosphate (P) transporters involved in transcellular Pb, Cd and As transport in the duodenum of mice was quantified using real-time polymerase chain reaction. Serum 1,25-Dihydroxyvitamin D3 [], parathyroid hormone (PTH), and renal CYP27B1 activity controlling synthesis were measured using ELISA kits. Metal(loid) speciation in the feces of mice was characterized using X-ray absorption near-edge structure (XANES) spectroscopy. In general, mice exposed to each of the Ca minerals exhibited lower Pb-, Cd-, and As-RBA for three dusts. However, RBAs with the different Ca minerals varied. Among minerals, mice fed dietary did not exhibit lower duodenal mRNA expression of Ca transporters but did have the lowest Pb and Cd oral bioavailability at the highest Ca concentration (; 51%-95% and 52%-74% lower in comparison with the control). Lead phosphate precipitates (e.g., chloropyromorphite) were observed in feces of mice fed dietary . In comparison, mice fed organic Ca minerals (Ca gluconate, Ca lactate, Ca aspartate, and Ca citrate) had lower duodenal mRNA expression of Ca transporters, but Pb and Cd oral bioavailability was higher than in mice fed . In terms of As, mice fed Ca aspartate exhibited the lowest As oral bioavailability at the highest Ca concentration (; 41%-72% lower) and the lowest duodenal expression of P transporter (88% lower). The presence of aspartate was not associated with higher As solubility in the intestine. Our study used a mouse model of exposure to household dust with various concentrations and species of Ca to determine whether different Ca minerals can reduce bioavailability of Pb, Cd, and As in mice and elucidate the mechanism(s) involved. This study can contribute to the practical application of optimal Ca minerals to protect humans from Pb, Cd, and As coexposure in the environment. https://doi.org/10.1289/EHP11730.

De novo transcriptome assembly of Aureobasidium melanogenum CGMCC18996 to analyze the β-poly(L-malic acid) biosynthesis pathway under the CaCO3 addition

β-Poly(L-malic acid) (PMLA) is a water-soluble biopolymer used in food, medicine and other industries. To date, the biosynthesis pathway of PMLA has not been fully elucidated. In this study, we sequenced the transcriptome of strain Aureobasidium melanogenum under 20 g/L CaCO3 addition. The resulting sequencing reads were assembled and annotated for the differentially expressed genes (DEGs) analysis and novel transcripts identification. The result indicated that with the CaCO3 addition, the tricarboxylic cycle (TCA) cycle and glyoxylate pathway were up-regulated, and it also found that a non-ribosomal peptide synthetase (NRPS) like protein was highly expressed. The DEGs analysis showed a high expression level of malate dehydrogenase (MDHC) and phosphoenolpyruvate carboxykinase (PCKA) in the CaCO3 group, which indicated a cytosolic malate activity. We speculated that the malate should be transported to or synthesized in the cytoplasm, which was then polymerized to PMLA by the NRPS-like protein, accompanied by the up-regulated TCA cycle providing ATP for the polymerization. Depending on the analysis, we assumed that an NRPS-like protein, the TCA cycle, and the cytosolic malate together are contributing to the PMLA biosynthesis.

Probiotics encapsulated gastroprotective cross-linked microgels: Enhanced viability under stressed conditions with dried apple carrier.

In the current study, Lactobacillus acidophilus was encapsulated in sodium alginate and whey protein isolate, with the addition of antacids CaCO3 or Mg(OH)2. The obtained microgels were observed by scanning electron microscopy. Encapsulated and free probiotics were subjected to vitality assay under stressed conditions. Furthermore, dried apple snack was evaluated as a carrier for probiotics for 28 days. A significant (p≤ .05) effect of antacid with an encapsulating agent was observed under different stressed conditions. During exposure to simulated gastrointestinal conditions, there were observations of 1.24 log CFU and 2.17 log CFU, with corresponding 0.93 log CFU and 2.63 log CFU decrease in the case of SA + CaCO3 and WPI + CaCO3 respectively. Likewise, high viability was observed under thermal and refrigerated conditions for probiotics encapsulated with SA + CaCO3. In conclusion, the results indicated that alginate microgels with CaCO3 are effective in prolonging the viability of probiotics under stressed conditions.

New insight into the changes in metal-phosphonate complexes from the addition of CaCO3 to enhance ferric flocculation for efficient phosphonate removal

Due to the stable chelating effect of organic phosphonates in wastewater, phosphonates with increasing emission are difficult to be removed effectively by traditional ferric salt flocculation, which has posed tough challenges for reducing total phosphorus pollution in recent years. In this work, calcium carbonate (CaCO3) was introduced to work together with the widely investigated flocculant of ferric chloride (FeCl3) to realize an efficient removal of nitrilotrismethylenephosphonic acid (NTMP) at much lower dosage of FeCl3. With an aid of synergy effect from together use of CaCO3 and FeCl3, the remaining concentration as low as 0.16 mg−P/L, far below the sewage discharge limit (0.5 mg−P/L), was simply obtained with a significantly reduced Fe/P molar ratio at only 4, resulting from calcium source donor to form more stable Fe–Ca–P tridentate bridging complexes, high affinity towards ferric ions on CaCO3 surface and slow-release alkaline from CaCO3. A comparison among sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2) and CaCO3 as additives, was carried out to highlight the advantages of using CaCO3 and clarify the mechanism for the greatly improved performance by a set of characterizations including XRD, FTIR, Zeta potential, XPS, SEM−EDS and TG analyses. The addition of CaCO3 in ferric flocculation resulted in further obvious advantages such as 75% shortened settling time and only one−third of sludge volume of the precipitant, beneficial to the sample handling in engineering application. The proposed new approach has been further confirmed to work efficiently on real phosphonate-containing wastewater. Discussion on the interaction between CaCO3 and ferric salts in phosphonate solutions shed new insights into the working mechanism of using CaCO3 for the treatment of phosphonates-containing wastewater.