Effect of Nutrient Solution Composition on Bio-Cemented Sand

Microbial-induced carbonate precipitation is an environmentally friendly foundation treatment technology that effectively improves soil engineering performance. The various nutrient components of liquid curing compounds significantly influence the curing effect. On the basis of penetration, dry density, water absorption, and unconfined compressive strength tests, this study showed the effect of nutrient solution composition, including urea, calcium chloride, sodium bicarbonate, ammonium chloride, and nutrient broth, on the physicomechanical properties of bio-cemented sand. The morphological differences of calcium carbonate precipitates under nutrient solution composition were compared through scanning electron microscopy (SEM). Results showed that the curing effect of compound nutrient solution was improved compared with the basic nutrient solution (urea and calcium chloride). Among the individual components added, ammonium chloride had the most remarkable effect, followed by sodium bicarbonate and nutrient broth. Among the paired components added, sodium bicarbonate + ammonium chloride had the most significant effect, followed by sodium bicarbonate + nutrient broth and ammonium chloride + nutrient broth. The strength of bio-cemented sand cured with compound nutrient solution containing five components could reach 3.43 MPa, which was 1.92 times higher than the strength of the basic nutrient solution. As shown by the SEM image, the calcium carbonate precipitation in the solidified sand was distributed in the clearance of sand particles, effectively bonding the sand particles. The calcium carbonate obtained by the composition of the compound nutrient solution precipitated the sand particles, and some of the sand particles were wrapped. Moreover, the amount of precipitation was evidently greater than that of the basic nutrient solution. Compared with the basic nutrient solution, the compound nutrient solution effectively reduced the apparent porosity and average pore size of the sand. Thus, the curing effect of the compound nutrient solution was better than that of the basic nutrient solution.

Effects of Viscosities and Solution Composition on Core-Sheath Electrospun Polycaprolactone(PCL) Nanoporous Microtubes

Vascularization for tissue engineering applications has been challenging over the past decades. Numerous efforts have been made to fabricate artificial arteries and veins, while few focused on capillary vascularization. In this paper, core-sheath electrospinning was adopted to fabricate nanoporous microtubes that mimic the native capillaries. The results showed that both solution viscosity and polyethylene oxide (PEO) ratio in polycaprolactone (PCL) sheath solution had significant effects on microtube diameter. Adding PEO into PCL sheath solution is also beneficial to surface pore formation, although the effects of further increasing PEO showed mixed results in different viscosity groups. Our study showed that the high viscosity group with a PCL/PEO ratio of 3:1 resulted in the highest average microtube diameter (2.14 µm) and pore size (250 nm), which mimics the native human capillary size of 1–10 µm. Therefore, our microtubes show high potential in tissue vascularization of engineered scaffolds.

Soot and charcoal are reservoirs of extracellular DNA

Soot and charcoal are carbonaceous materials widespread in the environment where they readily can come in contact with extracellular DNA shed from organisms. The adsorption at a surface protects DNA from chemical and biological degradation. However, a comprehensive insight into DNA adsorption at soot and charcoal is lacking. We measured DNA adsorption capacity at soot and charcoal as a function of solution composition, time and DNA length. We observed that the capacity for DNA is the highest at low pH, it increases with solution concentration and cation valency and that the activation energy for DNA adsorption at both soot and charcoal is ~50 kJmol-1. We demonstrate how the interaction between DNA and soot and charcoal partly occurs via terminal basepairs, suggesting that, besides electrostatic forces, hydrophobic interactions play an important role in binding. The importance of hydrophobic interactions increases as the hydrophobicity of a surface increases. Such strong binding and hydrophobic interactions need to be taken into account to improve DNA extraction protocols and for mitigation of the spread of antibiotic resistance genes in environmental matrices that contain soot and charcoal such as aerosol, wastewater and topsoil.

Recovery of niobium from wastes generated in titanium production by cation exchange sorbents

This article presents the technology of niobium recovery by processing of chloride residues generated during the chlorination of titanium slags. For waste processing, a two-stage leaching technology is proposed. Water is used at the first stage of leaching and hydrochloric acid 4.0 M is used at the second stage. For the purpose of sorption of niobium from the solution composition obtained during leaching, cation-exchange sorbents Purolite-C104 and KU-2-8 H were used. By the usage of Purolite-C104 ion exchange resin the sorption efficiency of niobium from a solution with a concentration of 2 g/l was about 71.0 % (0.071 g/g) in 3.5 hours, while for KU-2-8 H ion exchange resin, sorption efficiency was about 89.0 % (0.089 g/g).

Optimized Stoichiometry for CuCrO2 Thin Films as Hole Transparent Layer in PBDD4T-2F:PC70BM Organic Solar Cells

The performance and stability in atmospheric conditions of organic photovoltaic devices can be improved by the integration of stable and efficient photoactive materials as substituent of the chemically unstable poly (3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS), generally used as organic hole transport layer. Promising candidates are p-type transparent conductive oxides, which combine good optoelectronic and a higher mechanical and chemical stability than the organic counterpart. In this work, we synthesize Cu-rich CuCrO2 thin films by aerosol-assisted chemical vapour deposition as an efficient alternative to PEDOT:PSS. The effect of stoichiometry on the structural, electrical, and optical properties was analysed to find a good compromise between transparency, resistivity, and energy bands alignment, to maximize the photovoltaic performances., Average transmittance and bandgap are reduced when increasing the Cu content in these out of stoichiometry CuCrO2 films. The lowest electrical resistivity is found for samples synthesized from a solution composition in the 60–70% range. The optimal starting solution composition was found at 65% of Cu cationic ratio corresponding to a singular point in Hackee’s figure of merit of 1 × 10−7 Ω−1. PBDD4T-2F:PC70BM organic solar cells were fabricated by integrating CuCrO2 films grown from a solution composition ranging between 40% to 100% of Cu as hole transport layers. The solar cells integrating a film grown with a Cu solution composition of 65% achieved a power conversion efficiency as high as 3.1%, representing the best trade-off of the optoelectronic properties among the studied candidates. Additionally, despite the efficiencies achieved from CuCrO2-based organic solar cells are still inferior to the PEDOT:PSS counterpart, we demonstrated a significant enhancement of the lifetime in atmospheric conditions of optimal oxides-based organic photovoltaic devices.

Morphologies and Structure of Brain Lipid Membrane Dispersions

This study aims to explore the variety of previously unknown morphologies that brain lipids form in aqueous solutions. We study how these structures are dependent on cholesterol content, salt solution composition, and temperature. For this purpose, dispersions of porcine sphingomyelin with varying amounts of cholesterol as well as dispersions of porcine brain lipid extracts were investigated. We used cryo-TEM to investigate the dispersions at high-salt solution content together with small-angle (SAXD) and wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) for dispersions in the corresponding salt solution at high lipid content. Sphingomyelin forms multilamellar vesicles in large excess of aqueous salt solution. These vesicles appear as double rippled bilayers in the images and as split Bragg peaks in SAXD together with a very distinct lamellar phase pattern. These features disappear with increasing temperature, and addition of cholesterol as the WAXD data shows that the peak corresponding to the chain crystallinity disappears. The dispersions of sphingomyelin at high cholesterol content form large vesicular type of structures with smooth bilayers. The repeat distance of the lamellar phase depends on temperature, salt solution composition, and slightly with cholesterol content. The brain lipid extracts form large multilamellar vesicles often attached to assemblies of higher electron density. We think that this is probably an example of supra self-assembly with a multiple-layered vesicle surrounding an interior cubic microphase. This is challenging to resolve. DSC shows the presence of different kinds of water bound to the lipid aggregates as a function of the lipid content. Comparison with the effect of lithium, sodium, and calcium salts on the structural parameters of the sphingomyelin and the morphologies of brain lipid extract morphologies demonstrate that lithium has remarkable effects also at low content.

Relation between soil solution composition and petiole cellular extract of crops in western Mexico

Crop fertilization greatly impacts food production. However, insufficient applications can lead to poor yields. On the other hand, an excessive application leads to soil and aquifers pollution. In this paper, field studies were carried out to determine the ranges of mineral concentration and the interaction of the ions in the soil solution (SS) and the petiole cellular extract (PCE) in several cultures established in the states of Guanajuato, Colima and Jalisco, Mexico. The hypothesis states that there is a causal relationship between the mineral composition of the soil solution (SS) and the minerals and total soluble solids (TSS) in petiole cellular extract (PCE). The following cultures were studied in this research: avocado, blueberry, broccoli, cauliflower, raspberry, strawberry, lettuce, cantaloupe, papaya, and pepper. For each culture, PCE samples and SS samples using a press to break tissue and ceramic tip lysimeters were obtained. The results were processed to obtain ranges of variation within 50% of the closest values to the median. Correlations between the several ion concentrations were analyzed using analysis of variance. The results showed values (mg L-1) of NO3- (40-620), PO43- (17-66), K+ (3-377), Ca2+ (27-582), Na+ (15.3-500), Mg2+ (10-53), Fe3+ (0.6‑1.8), and Zn2+ (2.8-7.4) in soil solution, which allowed obtaining values of NO3- (27-9225), K+ (820-9375), Ca2+ (1.0-650), Na+ (25-620) and TSS (2-13 °Brix) in petiole cellular extract of petiole. Statistically significant correlations were observed between the concentrations of the SS ions regarding the concentrations in PCE in crops suggesting a relationship between the plant nutritive assimilation and cations or anions present in soil solution. The conclusion derived from this study is that ionic concentration ranges registered in the SS and in the PCE provide an approximation to the ranges of nutritional sufficiency for the horticultural crops established in the summer-winter in western Mexico.