Effect of Humic Acid on Adsorption of Polychlorinated Biphenyls onto Organoclay

Mitigation of risks stemming from contaminated sediments in freshwater and estuarine environments remains an important challenge to the field of environmental science and engineering. Capping sediments with reactive materials is one approach that has recently been the subject of research and development. This research evaluated the use of organoclay as a sorbent in a reactive cap for in situ remediation of contaminated sediments, and provides an original contribution by presenting the sorption characteristics of individual polychlorinated biphenyls (PCB) congeners in the presence of high concentrations of humic acids typical of sediment porewater environments. Sorption of coplanar and noncoplanar PCBs on three commercially available organoclays was studied in this work. Studies were conducted to evaluate the kinetics of adsorption of PCBs on organoclay and to determine the effect of humic acid on the kinetics of adsorption. Isotherm studies were conducted to determine the adsorption affinity of PCBs for organoclays in the presence and absence of humic acid. Studies showed a 45 to 96% reduction in the sorption affinity for organoclays after preloading with high concentrations of humic acid, depending both on the congener and the composition of organoclay. Desorption of PCBs upon addition of humic acid after PCBs were equilibrated with organoclay was statistically significant, although the magnitude of the effect was much smaller than that observed from preloading of humic acid

Evaluation of Activated Carbon as a Reactive Cap Sorbent for Sequestration of PCBs in Presence of Humic Acid

This study investigated the interferences caused by high humic acid concentrations on the adsorption of coplanar and noncoplanar polychlorinated biphenyls (PCBs) on coconut shell activated carbon. In particular, the research focuses on the application of activated carbon as a reactive cap for contaminated sediment sites, a possible intervention to reduce contaminant flux through pore water, and to organisms in aquatic environments. Kinetic and equilibrium studies were conducted using activated carbon as a sorbent for individual PCB congeners including BZ 1, 52, 77, 153, and 169, respectively, in the presence and absence of humic acid. Results showed that preloading of activated carbon with humic acid significantly reduced the adsorption affinity for all selected PCB congeners. Experiments conducted without preloading of activated carbon demonstrated that desorption upon subsequent spiking with humic acid (simulating long-term exposure to pore water that contains high humic acid concentrations) was not found to be statistically significant, and varied with coplanarity of PCBs. Results provide important information for the design of reactive caps in sediments where high concentrations of dissolved organic carbon are found, and highlight the importance of considering site conditions when designing effective reactive caps

Across-Column Cracks and Axial Splits in S2 Saline Ice under Compression

Experiments on plate-like specimens have established that across-column cracks from within S2 (columnar) salt-water ice when compressed uniaxially along a direction inclined to the long axis of the grains. Wing cracks initiate from the across-column cracks and lengthen into axial splits when the ice is rapidly deformed; correspondingly; the macroscopic behavior changes from ductile to brittle. The across-column cracking is attributed to grain-boundary sliding, and the splitting to the suppression of crack-tip creep

Mutual Fund Tournaments: Evidence From Global And International Funds

For a sample of global and international equity mutual funds, we test the proposition that managers likely to end up as losers manipulate fund risk differently from interim winners. In contrast with Brown, Harlow, and Starks (1996) who found robust support for the tournament model, we found no evidence of tournament like behavior for international and global mutual funds. A possible explanation of this behavior is that investors in these funds are primarily seeking diversification and therefore are less sensitive to relative performance

Impact of community pharmacist intervention on concurrent benzodiazepine and opioid prescribing patterns

Objectives (1) To evaluate the number of opioid/benzodiazepine (BZD) prescription changes resulting from pharmacist communication to prescriber(s); (2) to determine the number of patients on concurrent opioid/BZD therapy from single versus multiple prescribers; (3) to compare the number of opioid/BZD prescription changes resulting from communication when a single versus multiple prescribers was involved in a patient’s care; and (4) to compare the number of opioid/BZD prescription changes resulting from communication via fax versus the Kansas Health Information Network (KHIN) direct messaging feature. Methods Prospective study conducted at 13 community pharmacies, including patients 18 years of age or older simultaneously filling opioid and BZD prescriptions within 90 days before October 2017. Prescribers received faxed or KHIN communication proposing evidence-based prescription changes to opioid/BZD agents. Prescription changes were evaluated weekly for 3 months after the initial intervention. Descriptive statistics assessed demographics and the number and types of prescription changes. Spearman rho correlations compared prescription changes and number of prescriptions to number of prescribers; a priori alpha was set at 0.05. Results A total of 137 prescribers and 121 patients were included. Ninety-nine prescribers were contacted via fax and 38 via KHIN. After 4 weeks, 34 recommendations were received: 20 responses (59%) indicated rejection of recommendations, 5 (15%) approved BZD taper/discontinuation, 3 (9%) deferred changes until a patient visit, 2 (6%) approved opioid taper/discontinuation, 2 (6%) prescribed naloxone, and 2 (6%) withdrew from the patient’s care. Three months after communication, 35 prescription changes were noted: 22 (63%) opioid/BZD agent tapers/discontinuation, 14 (26%) opioid/BZD dose increases, and 2 (6%) naloxone prescriptions. There was positive correlation between the number of tapered/discontinued agents and the number of prescribers involved in a patient’s care (P = 0.046). Conclusion A faxed pharmacist intervention may help to reduce opioid/BZD coprescribing, especially when multiple providers are involved in a patient’s care

Using NAI detectors for tomographic gamma scanning

The authors examined two approaches for using NaI detectors to perform transmission corrections used in the tomographic gamma scanner (TGS) and segmented gamma scanner (SGS) nondestructive assay methods. They found that a material-basis-set (MBS) fit using empirical logarithmic response spectra is quite accurate. Because this is a gross count technique, it gives sensitivities (for equal numbers of detectors) that are roughly ten times better than those obtained using Germanium detectors. The authors also found that simple continuum subtraction can be used in MBS fits using the energy-group-analysis technique only when the Pu transmission is greater than 10%. Both approaches for using NaI detectors require a knowledge of the Pu (or other) isotopics to obtain full accuracy

Heart Failure in Hispanic Americans: Improving Cultural Awareness

Hispanic Americans are the largest and fastest growing ethnic group in the United States. Hispanic Americans have high rates of heart failure (HF) risk factors, such as hypertension, diabetes mellitus, obesity, obstructive sleep disorders, and dyslipidemia. Certain unique HF risk factors prominent among Hispanic Americans are uncommon in the general population, such as younger onset of valvular disease and Chagas disease. Advanced practice nurses providing care to Hispanic Americans have an ethical obligation to provide culturally competent care and assist these patients in overcoming barriers to health care so that they can effectively manage their HF

Patterns of DNA Methlyation across the Leptin Core Promoter in Four Diverse Asian and North American Populations

DNA methylation is the most widely studied of epigenetic mechanisms, with environmental effects recorded through patterned attachments of methyl groups along the DNA that are capable of modifying gene expression without altering the DNA sequencing. The degree to which these patterns of DNA methylation are heritable, the expected range of normality across populations, and the phenotypic relevance of pattern variation remain unclear. Genes regulating metabolic pathways appear to be vulnerable to ongoing nutritional programming over the life course, as dietary nutrients are significant environmental determinants of DNA methylation, supplying both the methyl groups and energy to generate the methylation process. Here we examine methylation patterns along a region of the metabolic gene leptin (LEP). LEP's putative functions include regulation of energy homeostasis, with its signals affecting energy intake and expenditure, adipogenesis and energy storage, lipid and glucose metabolism, bone metabolism, and reproductive endocrine function. A pattern of differential methylation across CpG sites of the LEP core promoter has been previously identified; however, any consistency of pattern or its phenotypic significance is not fully elucidated among populations. Using DNA extracted from unfractionated white blood cells of peripheral blood samples, our pilot study, divided into two parts, examined the significance of variation in DNA methylation patterns along the leptin core promoter in four populations (phase 1) and used biomarkers reflecting leptin's functional process in two of those populations, western Buryat of Siberia and the Mennonite of central Kansas, to investigate the relevance of the ethnic variation identified in the DNA methylation (phase 2). LEP's core promoter region contains both the binding site for C/EBPα (CCAAT/enhancer binding protein alpha), which tempers the final step in adipocyte maturity and capacity to synthesize leptin, and the TATA motif controlling leptin synthesis. Previous studies report that increased methylation in this region is correlated to decreased gene expression, suggesting tissue-specific methylation variation at this region (Melzner et al. 2002). We hypothesized that evidence of nutritional epigenetic programming would be identified through variation in patterns of DNA methylation and that functional relevance of that variation among populations would be identified through biomarkers that reflect leptin's metabolic signals: serum leptin levels, lipoproteins of the lipid transport system, and anthropometric measures. In phase 1, our combined analyses of 313 individuals documented a distinct and consistent overall pattern of differential DNA methylation across seven CpG sites of LEP core promoter in all ethnicities and both sexes. This pattern replicates those identified in previous studies, suggesting a conserved core promoter region across populations. Phase 2 analyses of two of the four populations (n = 239), correlating methylation at the C/EBPα transcription binding site (TBS) with metabolic and anthropometric biomarkers reflecting LEP roles, showed that stature, which reflects bone growth and remodeling, was significantly and inversely correlated with the percentage of DNA methylation at this site in both sexes. We suggest that variation in DNA methylation along the LEP core promoter plays a substantial role in energy signals affecting both adipogenesis and bone metabolism

Demonstration of Machine Learning-Based Model-Independent Stabilization of Source Properties in Synchrotron Light Sources.

Synchrotron light sources, arguably among the most powerful tools of modern scientific discovery, are presently undergoing a major transformation to provide orders of magnitude higher brightness and transverse coherence enabling the most demanding experiments. In these experiments, overall source stability will soon be limited by achievable levels of electron beam size stability, presently on the order of several microns, which is still 1-2 orders of magnitude larger than already demonstrated stability of source position and current. Until now source size stabilization has been achieved through corrections based on a combination of static predetermined physics models and lengthy calibration measurements, periodically repeated to counteract drift in the accelerator and instrumentation. We now demonstrate for the first time how the application of machine learning allows for a physics- and model-independent stabilization of source size relying only on previously existing instrumentation. Such feed-forward correction based on a neural network that can be continuously online retrained achieves source size stability as low as 0.2  μm (0.4%) rms, which results in overall source stability approaching the subpercent noise floor of the most sensitive experiments