Influence and interactions of multi-factors on the bioavailability of PAHs in compost amended contaminated soils

Compost amendment to contaminated soils is a potential approach for waste recycling and soil remediation. The relative importance and interactions of multiple factors on PAH bioavailability in soils were investigated using conjoint analysis and five-way analysis of variance. Results indicated that soil type and contact time were the two most significant factors influencing the PAH bioavailability in amended soils. The other two factors (compost type and ratio of compost addition) were less important but their interactions with other factors were significant. Specifically the 4-factor interactions showed that compost addition stimulated the degradation of high molecular PAHs at the initial stage (3 month) by enhancing the competitive sorption within PAH groups. Such findings suggest that a realistic decision-making towards hydrocarbon bioavailability assessment should consider interactions among various factors. Further to this, this study demonstrated that compost amendment can enhance the removal of recalcitrant hydrocarbons such as PAHs in contaminated soils

Recycling of solvent used in a solvent extraction of petroleum hydrocarbons contaminated soil.

The application of water washing technology for recycling an organic composite solvent consisting of hexane and pentane (4:1; TU-A solvent) was investigated for extracting total petroleum hydrocarbons (TPH) from contaminated soil. The effects of water volume, water temperature, washing time and initial concentration of solvent were evaluated using orthogonal experiments followed by single factor experiments. Our results showed that the water volume was a statistically significant factor influencing greatly the water washing efficiency. Although less important, the other three factors have all increased the efficacy of water washing treatment. Based on a treatment of 20g of contaminated soil with a TPH concentration of 140mgg(-1), optimal conditions were found to be at 40°C, 100mL water, 5min washing time and 660mgg(-1) solvent. Semi-continuous water extraction method showed that the concentration of the composite solvent TU-A was reduced below 15mgg(-1) d.w. soil with a recovery extraction efficiency >97%. This finding suggests that water washing is a promising technology for recycling solvent used in TPH extraction from contaminated soil

Noncovalently Modified Carbon Nanotubes with Carboxymethylated Chitosan: A Controllable Donor-Acceptor Nanohybrid

We report here the modification of multiwalled carbon nanotubes (MWNTs) with a kind of polysaccharide, carboxymethylated chitosan (cmCs), and their potential usage as donor-acceptor nanohybrids. The modified composites (cmCs/MWNTs) were characterized by high-resolution TEM, FT-IR, TGA and time-resolved spectroscopy. The time-resolved spectroscopic experiments revealed that interfacial electron transfer readily takes place between MWNTs and surface immobilized cmCs chains. The forward electron transfer is fast (< 20 ns) while the backward recombination is slow. The recombination process strongly depends on the chain length of carboxylmethylated chitosan, i.e. a shorter recombination lifetime (~1.1 μs) for the shorter-chain cmCs coated MWNTs against that of the longer-chain cmCs coated MWNTs (~3.5 μs). The results demonstrated that the cmCs/MWNTs composite may be applied as a controllable donor-acceptor nanohybrid

Correlating asphaltene dimerization with its molecular structure by potential of mean force calculation and data mining

Asphaltene aggregation affects the entire production chain of the petrochemical industry, which also poses environmental challenges for oil pollution remediation. The aggregation process has been investigated for decades, but it remains unclear how the free energy of asphaltene association in solvents is correlated to its molecular structure. In this study, dimerization energies of 28 types of asphaltenes in water and toluene were calculated using the umbrella sampling method. Structural parameters related to the atom types and functional groups were screened to identify the factors most influencing the dimerization energy using multiple linear regression, multilayer perceptron, and support vector regression. Results demonstrated that the influence of molecular structure on asphaltene association in water was nonlinear, while attempts to capture the relationship using linear regression had larger error. The linkage per aromatic ring, number of aromatic carbons, and number of aliphatic chains were the top three factors accounting for 52% of the dimerization energy variation in water. Asphaltene dimerization in toluene was dominated by the content of sulfur in aromatic rings and the number of aromatic carbons which contributed to 55% of the energy variation. To the best of our knowledge, this was the first study successfully predicting asphaltene dimerization using molecular structure (R > 0.9) and quantifying simultaneously the relative importance of each structural parameter. The proposed modeling approach supported the decision making on the number of structural parameters to investigate for predicting asphaltene aggregation

Construction of a Recombinant Eukaryotic Expression Plasmid Containing Human Calcitonin Gene and Its Expression in NIH3T3 Cells

Aim. To construct a recombinant eukaryotic expression plasmid containing human calcitonin (hCT) gene and express the gene in murine fibroblast NIH3T3 cells. Materials and Methods. A murine Igκ-chain leader sequence and hCT gene were synthesized and cloned into pCDNA3.0 to form the pCDNA3.0-Igκ-hCT eukaryotic expression vector, which was transfected into NIH3T3 cells. The mRNA and protein expressions and secretion of hCT were detected. Primarily cultured osteoclasts were incubated with the supernatant of pCDNA3.0-Igk-hCT-transfected NIH3T3 cells, and their numbers were counted and morphology observed. Results. The expression and secretion of hCT were successfully detected in pCDNA3.0-Igk-hCT-transfected NIH3T3 cells. The number of osteoclasts was decreased and the cells became crumpled when they were incubated with the supernatant of pCDNA3.0-Igk-hCT-transfected NIH3T3 cells. Conclusion. A recombinant eukaryotic expression vector containing hCT gene was successfully constructed and expressed in NIH3T3 cells. The secreted recombinant hCT inhibited the growth and morphology of osteoclasts

Diet-induced bacterial immunogens in the gastrointestinal tract of dairy cows: Impacts on immunity and metabolism

Dairy cows are often fed high grain diets to meet the energy demand for high milk production or simply due to a lack of forages at times. As a result, ruminal acidosis, especially subacute ruminal acidosis (SARA), occurs frequently in practical dairy production. When SARA occurs, bacterial endotoxin (or lipopolysaccharide, LPS) is released in the rumen and the large intestine in a large amount. Many other bacterial immunogens may also be released in the digestive tract following feeding dairy cows diets containing high proportions of grain. LPS can be translocated into the bloodstream across the epithelium of the digestive tract, especially the lower tract, due to possible alterations of permeability and injuries of the epithelial tissue. As a result, the concentration of blood LPS increases. Immune responses are subsequently caused by circulating LPS, and the systemic effects include increases in concentrations of neutrophils and the acute phase proteins such as serum amyloid-A (SAA), haptoglobin (Hp), LPS binding protein (LBP), and C-reactive protein (CRP) in blood. Entry of LPS into blood can also result in metabolic alterations. Blood glucose and nonesterified fatty acid concentrations are enhanced accompanying an increase of blood LPS after increasing the amount of grain in the diet, which adversely affects feed intake of dairy cows. As the proportions of grain in the diet increase, patterns of plasma β-hydoxybutyric acid, cholesterol, and minerals (Ca, Fe, and Zn) are also perturbed. The bacterial immunogens can also lead to reduced supply of nutrients for synthesis of milk components and depressed functions of the epithelial cells in the mammary gland. The immune responses and metabolic alterations caused by circulating bacterial immunogens will exert an effect on milk production. It has been demonstrated that increases in concentrations of ruminal LPS and plasma acute phase proteins (CRP, SAA, and LBP) are associated with declines in milk fat content, milk fat yield, 3.5% fat-corrected milk yield, as well as milk energy efficiency

Discovering burst patterns of burst topic in Twitter

National Research Foundation (NRF) Singapore under International Research Centres in Singapore Funding Initiativ

Detecting community pacemakers of burst topic in Twitter

National Research Foundation (NRF) Singapore under International Research Centres in Singapore Funding Initiativ

Thermal effect and active control on bistable behaviour of anti-symmetric composite shells with temperature-dependent properties

Anti-symmetric cylindrical shells with two stable configurations have been proved to offer novel morphing structures in advanced engineering fields. The bistable behaviour of anti-symmetric composite shells under thermomechanical loading is analysed herein theoretically combined with a finite element modelling. The properties of the composite material in current study are considered to be functions of temperature. The shell is subjected to two different thermal load, i.e. the uniform temperature field and through-thickness thermal gradient. The influence of this two temperature field on the shell’s stable shapes was predicted analytically, which thereafter is determined by finite element results. This provides a feasible approach of controlling the deformation of the bistable shell through adjusting the applied temperature field. For this purpose, a superposition of uniform temperature field and through-thickness thermal gradient is imposed and its influence on the bistable shapes of bistable shells is therefore investigated, which is of great importance to the design and application of morphing structures manufactured from bistable composite shells