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Microbially induced calcium carbonate precipitation (MICP) is a potential method for improvement of soil. A laboratory study was conducted to investigate the influence of temperatures for soil improvement by MICP. The ureolytic activity experiments, MICP experiments in aqueous solution and sand column using Sporosarcina pasteurii were conducted at different temperatures(10, 15, 20, 25 and 30°C). The results showed there were microbially induced CaCO3 precipitation at all the temperatures from 10 to 30°C. The results of ureolytic activity experiments showed that the bacterial had higher ureolytic activity at high temperatures within the early 20 hours, however, the ureolytic activity at higher temperatures decreased more quickly than at lower temperatures. The results of MICP experiments in aqueous solution and sand column were consistent with tests of ureolytic activity. Within 20 to 50 hours of the start of the test, more CaCO3 precipitation was precipitated at higher temperature, subsequently, the precipitation rate of all experiments decreased, and the higher the temperature, the faster the precipitation rate dropped. The final precipitation amount of CaCO3 in aqueous solution and sand column tests at 10 °C was 92% and 37% higher than that at 30 °C. The maximum unconfined compressive strength of MICP treated sand column at 10 °C was 135% higher than that at 30 °C. The final treatment effect of MICP at lower temperature was better than that at high temperature within the temperature range studied. The reason for better treatment effect at lower temperatures was due to the longer retention time of ureolytic activity of bacteria at lower temperatures.

This research work reports the magnetic adsorption of fluoride from drinking water through silica-coated Fe3O4 nanoparticles. Chemical precipitation and wet impregnation methods were employed to synthesize the magnetic nanomaterials. Moreover, the synthesized nanomaterials were characterized for physicochemical properties through scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray powder diffraction. Screening studies were conducted to select the best iron oxide loading (0.0–1.5 wt%) and calcination temperature (300–500 °C). The best selected nanomaterial (0.5Fe-Si-500) showed a homogenous FeO distribution with a 23.79 nm crystallite size. Moreover, the optimized reaction parameters were: 10 min of contact time, 0.03 g L−1 adsorbent dose, and 10 mg L−1 fluoride (F−) concentration. Adsorption data were fitted to the Langmuir and Freundlich isotherm models. The Qm and KF (the maximum adsorption capacities) values were 5.5991 mg g−1 and 1.869 L g−1 respectively. Furthermore, accelerated adsorption with shorter contact times and high adsorption capacity at working pH was among the outcomes of this research work.

In this paper, α-Fe 2 O 3 was prepared by hydrothermal and chemical precipitation methods, respectively, and its gas sensing properties toward CH 4 were systematically studied. The larger specific surface area of the materials provided them potential and considerable gas adsorption abilities. The results of gas-sensing measurements indicated the synthesized α-Fe 2 O 3 materials presented a p-type conductive nature. The sensitivities of the devices based on the different material fabrication methods were measured to be 195% and 214%, respectively, at 370°C for the concentration of 2000 ppm CH 4 . In addition, the sensing mechanism was discussed and simulated by first-principles calculation. The results revealed the higher surface adsorption energy of α-Fe 2 O 3 , which verified the experimental conclusions of our work. Our research suggests that α-Fe 2 O 3 is a promising candidate for CH 4 gas sensing in many fields such as mining safety and environmental monitoring.

In the current study, the combined anti-tumor efficacy of bioactive hydroxyapatite nano- particles (HA-NPs) loaded with altretamine (ALT) was evaluated. The well-known fact that HA has great biological compatibility was confirmed through the findings of the hemolytic experiments and a maximum IC value seen in the MTT testing. The preparation of HA-NPs was performed using the chemical precipitation process. An in vitro release investigation was conducted, and the results demonstrated the sustained drug release of the altretamine-loaded hydroxyapatite nanoparticles (ALT-HA-NPs). Studies using the JURKAT E6.1 cell lines MTT assay, and cell uptake, as well as in vivo pharmacokinetic tests using Wistar rats demonstrated that the ALT-HA-NPs were easily absorbed by the cells. A putative synergism between the action of the Ca ions and the anticancer drug obtained from the carrier was indicated by the fact that the ALT-HA-NPs displayed cytotoxicity comparable to the free ALT at 1/10th of the ALT concentration. It has been suggested that a rise in intracellular Ca ions causes cells to undergo apoptosis. Ehrlich's ascites model in Balb/c mice showed comparable synergistic efficacy in a tumor regression trial. While the ALT-HA-NPs were able to shrink the tumor size by six times, the free ALT was only able to reduce the tumor volume by half.

Biomolecules play key roles in regulating the precipitation of CaCO biominerals but their response to ocean acidification is poorly understood. We analysed the skeletal intracrystalline amino acids of massive, tropical Porites spp. corals cultured over different seawater pCO . We find that concentrations of total amino acids, aspartic acid/asparagine (Asx), glutamic acid/glutamine and alanine are positively correlated with seawater pCO and inversely correlated with seawater pH. Almost all variance in calcification rates between corals can be explained by changes in the skeletal total amino acid, Asx, serine and alanine concentrations combined with the calcification media pH (a likely indicator of the dissolved inorganic carbon available to support calcification). We show that aspartic acid inhibits aragonite precipitation from seawater in vitro, at the pH, saturation state and approximate aspartic acid concentrations inferred to occur at the coral calcification site. Reducing seawater saturation state and increasing [aspartic acid], as occurs in some corals at high pCO , both serve to increase the degree of inhibition, indicating that biomolecules may contribute to reduced coral calcification rates under ocean acidification.

Studies on chemical precipitation of the calcium orthophosphates have shown that their phase compositions do not vary depending on molar ratio Ca/P but are sensitive to solutions acidity and temperature. These are two key factors that determine the phase transformation progress of metastable phases into less soluble precipitates of the phosphates. It was proposed to compare calcium orthophosphates solubility products with calcium cations quantities in their formulas. It was found that there was a linear correlation between calcium orthophosphates specific solubility products and their molar ratios Ca/P if hydroxyapatite and its Ca-deficient forms were excluded from consideration. It was concluded that the relatively large deviations of their solubility products from the found correlation should be thought of as erroneous data. That is why solubility products were changed in accordance with correlation dependence: pKS for hydroxyapatite was 155, pKS for Ca-deficient hydroxyapatites was 114–155. The solubility isotherms, which were calculated on the basis of the corrected pKS values, coincided with the experimental data on solid-phase titration by Pan and Darvell.

The ethanol lock technique has shown great potential to eradicate organisms in biofilms and to treat or prevent central venous catheter related infections. Following instillation of ethanol lock solution, however, the inherent density gradient between blood and ethanol causes gravity induced seepage of ethanol out of the catheter and blood influx into the catheter. Plasma proteins so are exposed to highly concentrated ethanol, which is a classic agent for protein precipitation. We aimed to investigate the precipitating effect of ethanol locks on plasma proteins as a possible cause for reported catheter occlusions. Plasma samples were exposed in-vitro to ethanol (concentrations ranging from 7 to 70 v/v%) and heparin lock solutions. In catheter studies designed to mimic different in-vivo situations, the catheter tip was placed in a plasma reservoir and the material contained within the catheter was analyzed after ethanol lock instillation. The samples underwent standardized investigation for protein precipitation. Protein precipitation was observed in plasma samples containing ethanol solutions above a concentration of 28%, as well as in material retrieved from vertically positioned femoral catheters and jugular (subclavian) catheters simulating recumbent or head down tilt body positions. Precipitates could not be re-dissolved by dilution with plasma, urokinase or alteplase. Plasma samples containing heparin lock solutions showed no signs of precipitation. Our in-vitro results demonstrate that ethanol locks may be associated with plasma protein precipitation in central venous catheters. This phenomenon could be related to occlusion of vascular access devices locked with ethanol, as has been reported. Concerns should be raised regarding possible complications upon injection or spontaneous gravity induced leakage of such irreversibly precipitated protein particles into the systemic circulation. We suggest limiting the maximum advisable concentration of ethanol to 28 v/v% in catheter lock solutions.

A mixed sulfur–iron particles packed reactor (SFe reactor) was developed to simultaneously remove total nitrogen (TN) and total phosphorus (TP) of the secondary effluent from municipal wastewater treatment plants. Low effluent TN (<1.5 mg/L) and TP (<0.3 mg/L) concentrations were simultaneously obtained, and high TN removal rate [1.03 g N/(L·d)] and TP removal rate [0.29 g P/(L·d)] were achieved at the hydraulic retention time (HRT) of 0.13 h. Kinetic models describing denitrification were experimentally obtained, which predicted a higher denitrification rate [1.98 g N/(L·d)] of SFe reactor than that [1.58 g N/(L·d)] of sulfur alone packed reactor due to the mutual enhancement between sulfur-based autotrophic denitrification and iron-based chemical denitrification. A high TP removal obtained in SFe reactor was attributed to chemical precipitation of iron particles. Microbial community analysis based on 16S rRNA revealed that autotrophic denitrifying bacteria Thiobacillus and Sulfuricella were the dominant genus, indicating that autotrophic denitrification played important role in nitrate removal. These results indicate that sulfur and iron particles can be packed together in a single reactor to effectively remove nitrate and phosphorus.

Rod-shaped CoFe 2 O 4 was prepared by chemical precipitation–topotactic reaction method, and in this preparation needle-like γ-FeOOH and α-FeOOH were synthesized to use as template materials. The evolution of phase and morphology in the process of calcination exhibits that α-FeOOH and γ-FeOOH experienced different routes to form the α-Fe 2 O 3 middle phase with different crystallinity and morphology. The synthesis process of CoFe 2 O 4 revealed that the crystallinity, purity and morphology of CoFe 2 O 4 depend on the α-Fe 2 O 3 middle phase. The magnetic measurement showed that the CoFe 2 O 4 prepared from α-FeOOH has higher saturation magnetization and coercivity, and the crystallinity and morphology may play important roles in achieving a better magnetic performance.

Goethite is a stable and widespread mineral present in soil with many uses, and it affects the transportation and immobilization of heavy metals in solution. Nanogoethite was synthesized by a chemical precipitation method and used to batch adsorb U(VI) in solution. Adsorption experiments were used to understand the role of nanogoethite in controlling the U(VI) adsorption behavior in soil. The morphology and the crystallinity of nanogoethite were characterized by scanning electron microscopy and wide-angle X-ray powder diffractometry, respectively. The results showed that the crystallinity of nanogoethite after the adsorption of uranium did not change, but small particles appeared on the surface of the scales. The surface area was determined from N2 adsorption–desorption experiments using the Brunauer–Emmett–Teller to be 81.86 m2/g. The effects of factors such as the contact time, pH, adsorbent dosage, and the initial concentration of uranium on the adsorption of U(VI) were investigated. The experimental results showed that nanogoethite removed over 85% of the U(VI) in an aqueous 5.0 mg/L U(VI) solution at pH 4.0 and at 298 K. The pseudo-second-order model was used to simulate the adsorption process. The results show that chemisorption plays a major role in the adsorption process. The results of this study suggest that nanogoethite may play a significant role in controlling the migration and transfer of U(VI) in the soil, thus controlling the presence of U(VI) in soil.