Surfactant enhanced remediation of soil columns contaminated by residual tetrachloroethylene

The ability of aqueous surfactant solutions to recover tetrachloroethylene (PCE) entrapped in Ottawa sand was evaluated in four column experiments. Residual PCE was emplaced by injecting 14C-labeled PCE into water-saturated soil columns and displacing the free product with water. Miscible displacement experiments were conducted before and after PCE entrapment to determine the influence of residual PCE on column dispersivities. The first two column studies involved the injection of a 4% solution of polyoxyethylene (POE) (20) sorbitan monooleate, resulting in the removal of 90% and 97% of the residual PCE from 20-30- and 40-120-mesh Ottawa sand, respectively. Although micellar solubilization of PCE was the primary mode of recovery in these experiments, this process was shown to be rate-limited based on: (a) the disparity between initial steady-state concentrations of PCE in the column effluent and equilibrium values measured in batch experiments; and (b) the increase in effluent concentrations of PCE following periods of flow interruption. In the latter two experiments, surfactant solutions containing mixtures of sodium sulfosuccinates removed >99% of the residual PCE from soil columns packed with 40-270-mesh Ottawa sand. Approximately 80% of the PCE was mobilized as a separate organic liquid after lushing with -1) are not required to achieve significant PCE mobilization when buoyancy forces are important. The potential for displacement of dense nonaqueousphase liquids as a separate organic phase should, therefore, be evaluated during the selection of surfactant formulations for aquifer remediation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31591/1/0000520.pd

Comparative Analysis of the Microbial Profiles in Supragingival Plaque Samples Obtained From Twins With Discordant Caries Phenotypes and Their Mothers

Early childhood caries (ECC), the most frequent disease of oral cavity in preschool children, is the consequence of microbial, genetic, biochemical, socioeconomic, physical, environmental and health-influencing behavioral factors. To investigate the role of the oral microbiome and the impact of host and environmental factors in the occurrence and development of ECC, we studied the supragingival plaques of 14 twin pairs and a set of triplets with discordant caries phenotypes and 15 mothers, applying the Human Oral Microbe Identification using Next Generation Sequencing technique (HOMINGS). A total of 2,293,650 reads revealed 11 phyla, 116 genera, and 139 species of micromiome. Comparative analysis between the caries and caries-free group at species level revealed that the relative abundance of Streptococcus mutans, Lactobacillus fermentum, Actinomyces islaelii, Neisseria sica, and Veilonella dispar was much higher in caries group (P < 0.0001). Furthermore, monozygotic twins exhibited a higher degree of similarity than dizygotic twins. Finally, we analyzed the relationship between environmental factors and the oral microbiome, and our results indicat that the frequency of taking sweet food is associated with ECC. We conclude the following. First, the occurrence of Streptococcus mutans, Lactobacillus fermentum, Neisseria sica, and Veilonella dispar is strongly associated with the occurrence of ECC. Second, host genetic factors influence the oral microbiome composition, while environmental and behavioral factors like the frequency of taking sweet foods have an impact on the distribution of caries-related bacteria

A Study of Nonaqueous Phase Liquid Characterization and Surfactant Remediation

The objectives of this research were to identify and evaluate environmentally acceptable surfactants that could be used for surfactant enhanced aquifer remediation and to develop a partitioning tracer test method for the detection, estimation, and remediation performance assessment of subsurface nonaqueous phase liquids. First, a systematic approach for selection of surfactants for the remediation of nonaqueous phase liquid contaminated subsurface was developed. The approach entails the observations of the classical Winsor type phase behavior of the surfactant-water-tetrachloroethylene mixtures in calibrated test tubes. The basic observations consist of how many and what type of phases form, how fast equilibrium is approached, and how much tetrachloroethylene is solubilized. The mixtures of sodium diamyl, sodium dihexyl and sodium dioctyl sulfosuccinates were found to yield both Winsor Type I and Type III phase behavior based on the diamyl or dihexyl to dioctyl sulfosuccinate ratio and calcium chloride concentration, which are ideal properties for enhancing the solubility of tetrachloroethylene and lowering the interfacial tension to mobilize the residual tetrachloroethylene phase.The effectiveness of these sodium sulfosuccinate mixtures were then tested in sand column experiments to recover trapped residual tetrachloroethylene. The results of these column experiments show that the selected surfactants have the capacity to simultaneously enhance the aqueous solubility of tetrachloroethylene and to mobilize tetrachloroethylene as a separate phase and remove more than 99% of residual tetrachloroethylene from sandpack columns. The mobilization of trapped residual nonaqueous phase liquid was investigated from theoretical and experimental perspectives. A trapping number which combines the effects of buoyancy and viscous forces was derived. This trapping number option was implemented in UTCHEM, a three-dimensional chemical flood simulator developed at The University of Texas at Austin. From a practical perspective, the trapping number provides a basis for assessing the potential for dense nonaqueous phase liquid mobilization during surfactant remediation operation and minimizes the possibility of the uncontrolled downward migration of mobilized dense nonaqueous phase liquids into uncontaminated parts of the aquifer. The most important contribution of this research is the development of a new partitioning interwell tracer test method for detection, estimation, and remediation performance assessment purposes. The method can be used in both saturated and unsaturated soils contaminated by either light or dense nonaqueous phase liquids. The key elements that need to be considered when designing and interpreting a field-scale tracer test are discussed. Validation of this technique is illustrated by both laboratory column experiments and numerical simulation results. Finally, the design of two field partitioning interwell tracer tests, an unsaturated zone partitioning interwell tracer at the site of the Chemical Waste Landfill at Sandia National Laboratories and a saturated zone partitioning interwell tracer in an isolation test cell within Operable Unit 1 at Hill Air Force Base in Utah is presented.Petroleum and Geosystems Engineerin

Synergistic effects of sugar beet pectin and laccase on gel properties of egg white

It is of great significance to improve the gel properties of egg white for their related products. This goal was accomplished by investigating the gel properties of egg white via interacting with pectin and laccase, and revealing their mechanisms. Results showed that 0.06% sugar beet pectin (SBP) and 0.5 U/g laccase could endow egg white gels with better texture properties (with the highest hardness of 1 508.00 g, chewiness of 1 144.83, and gumminess of 1 210.57), and superior water holding capacity (WHC) (the highest WHC value of 72.08%). This was attributed to the fact that 0.06% of SBP filled the pores of egg white gel, and enhanced affinity and binding of the gels to water by the good hydrophilicity of SBP, and the decrease in egg white gel pore size. Laccase (0.5 U/g) could promote the cross-linking between the egg white gel and SBP to form a more complex gel network structure through the interactions between the tyrosine residues and ferulic acid in SBP, which brought more ionic bonds (22.47%), hydrogen bonds (12.4%), disulfide bonds (16.97%) and more compact structure to egg white gels. This work can provide an effective method to improve the quality of egg white gel and related products

In-Situ Characterization of Dense Non-Aqueous Phase Liquids Using Partitioning Tracers

Majors advances have been made during the past three years in our research on interwell partitioning tracers tests (PITTs). These advances include (1) progress on the inverse problem of how to estimate the three-dimensional distribution of NAPL in aquifers from the tracer data, (2) the first ever partitioning tracer experiments in dual porosity media, (3) the first modeling of partitioning tracers in dual porosity media (4) experiments with complex NAPLs such as coal tar, (5) the development of an accurate and simple method to predict partition coefficients using the equivalent alkane carbon number approach, (6) partitioning tracer experiments in large model aquifers with permeability layers, (7) the first ever analysis of partitioning tracer data to estimate the change in composition of a NAPL before and after remediation (8) the first ever analysis of partitioning tracer data after a field demonstration of surfactant foam to remediate NAPL and (9) experiments at elevated temperatures

In-Situ Characterization of Dense Non-Aqueous Phase Liquids Using Partitioning Tracers

Majors advances have been made during the past three years in our research on interwell partitioning tracers tests (PITTs). These advances include (1) progress on the inverse problem of how to estimate the three-dimensional distribution of NAPL in aquifers from the tracer data, (2) the first ever partitioning tracer experiments in dual porosity media, (3) the first modeling of partitioning tracers in dual porosity media (4) experiments with complex NAPLs such as coal tar, (5) the development of an accurate and simple method to predict partition coefficients using the equivalent alkane carbon number approach, (6) partitioning tracer experiments in large model aquifers with permeability layers, (7) the first ever analysis of partitioning tracer data to estimate the change in composition of a NAPL before and after remediation (8) the first ever analysis of partitioning tracer data after a field demonstration of surfactant foam to remediate NAPL and (9) experiments at elevated temperatures

Correction: Li et al. Altered Salivary Microbiome in the Early Stage of HIV Infections among Young Chinese Men Who Have Sex with Men (MSM). <i>Pathogens</i> 2020, <i>9</i>, 960

In the original publication [...

Table_4_The dynamic communities of oral microbiome in neonates.xlsx

The oral microbiome, associated with both oral disease and systemic disease, is in dynamic status along the whole life, and many factors including maternal microbiomes could impact the oral microbiome. While fewer studies have been conducted to study the characteristics of the oral microbiome in neonates and the associated maternal factors. Hence, we collected the microbiome of 15 mother-infant pairs across multiple body sites from birth up to 4 days postpartum and used high-throughput sequencing to characterize the microbiomes in mothers and their neonates. The oral microbiome in the neonates changed obviously during the 4 days after birth. Many bacteria originating from the vagina, skin, and environment disappeared in oral cavity over time, such as Prevotella bivia and Prevotella jejuni. Meanwhile, Staphylococcus epidermidis RP62A phage SP-beta, predominate bacterium in maternal skin microbiome and Streptococcus unclassified, main bacterium in vaginal microbiome, obviously increased in neonatal oral microbiome as time went on. Interestingly, as time progressed, the composition of the oral microbiome in the neonates was more similar to that of the milk microbiome in their mothers. Moreover, we found that the changes in the predominant bacteria in the neonates were in line with those in the neonates exposed to the environment. Together, these data described the sharp dynamics of the oral microbiome in neonates and the importance of maternal efforts in the development of the neonatal microbiome.</p