Impact Monitoring of the National Scale Up of Zinc Treatment for Childhood Diarrhea in Bangladesh: Repeat Ecologic Surveys

Charles Larson and colleagues find that 23 months into a national campaign to scale up zinc treatment for diarrhea in children under age 5 years, only 10% of children with diarrhea in rural areas and 20%–25% in urban/municipal areas were getting the treatment

Exploiting hydrophobic and electrostatic interactions for the effective removal of aqueous contaminants

Water treatment processes using membrane technology, electrochemistry and nanomaterials have shown tremendous promise in the last several years. While pressure driven membrane treatment processes are capable of treating water sources containing a wide variety of contaminants, they suffer from several challenges such as osmotic pressure limitations and surface scaling and fouling. Membrane distillation is a vapor pressure driven process that does not suffer from osmotic pressure limitations, and hence can be used for the treatment of high salinity sources. However, fouling is still a major concern, along with the added high energy requirements. In this work, we look at a membrane distillation system that successfully separated non-volatile contaminants from a dairy farm waste stream, resulting in a concentrated stream of nutrients to be used as fertilizer, and a dilute stream of volatile compounds that can be used as the feed in fermentation processes. We also looked at treatment of high salinity brines by membrane distillation. Due to the excellent heat and electrically conductive properties of carbon nanotubes, an electrically conducting membrane fabricated by coating a polymeric membrane with a carbon nanotube suspension proved successful in mitigating inorganic scaling to a large extent. The externally applied electric potential reduced scale deposition by electrostatic repulsion and electrokinetic mixing. In another aspect of our research activities, we studied the degradation of perfluoroalkyl substances, a class of contaminants of emerging concern that are highly recalcitrant carcinogenic compounds. Typical remediation of these compounds takes place through adsorption on activated carbon followed by incineration. Studies have shown that they can be degraded by electrochemical oxidation. We utilized the excellent sorption and electrically conductive properties of carbon nanotubes to develop a novel degradation mechanism, where an externally applied potential weakened the C-F bonds, and hydrated electrons generated by UV light resulted in defluorination. We extended this study to linear perfluoroalkyl substances having different chain lengths and headgroups, studied the feasibility of this mechanism on dechlorination of chlorinated solvents commonly co-occurring in groundwater, studied the impact of mixtures of perfluoroalkyl substances and verified the two-electron mechanism by evaluating degradation rates of isotopically labeled and unlabeled compounds

Comparative evaluation of the effectiveness of XP-endo Finisher and passive ultrasonic activation on dentinal tubule penetration of irrigation solution: A confocal laser scanning microscopy study

Aim: The aim of this in vitro study was to comparatively evaluate the effectiveness of XP-endo Finisher and passive ultrasonic (PU) activation on dentinal tubule penetration of irrigation solution: A confocal laser scanning microscopy study. Materials and Methods: Forty extracted single-rooted human mandibular canines and premolars were instrumented up to size 40/06 taper and randomly divided into 2 groups (n = 20) based on the activation technique of final irrigation solution into Group A: PU activation and Group B: XP-endo Finisher activation. In each group, 5 ml of 5% NaOCl labeled with fluorescent dye was used during activation as the final irrigation solution. Specimens were sectioned at 2, 5, and 8 mm from the apex and examined under confocal microscope to calculate the dentinal tubule penetration area. Data were analyzed using Tukey's post hoc tests (P = 0.05). Results: PU activation exhibited a significantly higher penetration area than XP-endo Finisher activation (P middle > apical) (P < 0.001). Conclusion: The PU activation is more effective than XP-endo Finisher in terms of irrigant penetration into the dentinal tubules

BTEX exposures in an area impacted by industrial and mobile sources: Source attribution and impact of averaging time

<p>The impacts of emissions plumes from major industrial sources on black carbon (BC) and BTEX (benzene, toluene, ethyl benzene, xylene isomers) exposures in communities located >10 km from the industrial source areas were identified with a combination of stationary measurements, source identification using positive matrix factorization (PMF), and dispersion modeling. The industrial emissions create multihour plume events of BC and BTEX at the measurement sites. PMF source apportionment, along with wind patterns, indicates that the observed pollutant plumes are the result of transport of industrial emissions under conditions of low boundary layer height. PMF indicates that industrial emissions contribute >50% of outdoor exposures of BC and BTEX species at the receptor sites. Dispersion modeling of BTEX emissions from known industrial sources predicts numerous overnight plumes and overall qualitative agreement with PMF analysis, but predicts industrial impacts at the measurement sites a factor of 10 lower than PMF. Nonetheless, exposures associated with pollutant plumes occur mostly at night, when residents are expected to be home but are perhaps unaware of the elevated exposure. Averaging data samples over long times typical of public health interventions (e.g., weekly or biweekly passive sampling) misapportions the exposure, reducing the impact of industrial plumes at the expense of traffic emissions, because the longer samples cannot resolve subdaily plumes. Suggestions are made for ways for future distributed pollutant mapping or intervention studies to incorporate high time resolution tools to better understand the potential impacts of industrial plumes.</p> <p><i>Implications</i>: Emissions from industrial or other stationary sources can dominate air toxics exposures in communities both near the source and in downwind areas in the form of multihour plume events. Common measurement strategies that use highly aggregated samples, such as weekly or biweekly averages, are insensitive to such plume events and can lead to significant under apportionment of exposures from these sources.</p

Comparative Evaluation of Two Different Fiber-Reinforced Composite Materials in Class 1 Post-Endodontic Restorations in Molars—A Randomized Clinical Study

This study aimed to evaluate and compare two different fiber-reinforced composite materials in class I post-endodontic restoration in molars. A total of 50 patients were randomly assigned into two groups (n = 25 for each group); group A: everX Posterior (packable composite) with a top layer of solareX (nano-hybrid composite) and group B: everX Flow (flowable composite) with a top layer of G-aenial universal injectable (flowable composite). Patients were evaluated immediately after the procedure (baseline), at 6 months, and at 1 year time intervals based on the modified USPHS criteria. The statistical analysis using a chi-square test showed no statistically significant difference in the clinical performance of group A and group B. Clinical performance of the combination of everX Flow with overlying G-aenial universal injectable composite proved to be comparable with everX Posterior with overlying solareX composite as post-endodontic restorations in class I lesions in permanent molars

Mineral Scale Prevention on Electrically Conducting Membrane Distillation Membranes Using Induced Electrophoretic Mixing.

The growth of mineral crystals on surfaces is a challenge across multiple industrial processes. Membrane-based desalination processes, in particular, are plagued by crystal growth (known as scaling), which restricts the flow of water through the membrane, can cause membrane wetting in membrane distillation, and can lead to the physical destruction of the membrane material. Scaling occurs when supersaturated conditions develop along the membrane surface due to the passage of water through the membrane, a process known as concentration polarization. To reduce scaling, concentration polarization is minimized by encouraging turbulent conditions and by reducing the amount of water recovered from the saline feed. In addition, antiscaling chemicals can be used to reduce the availability of cations. Here, we report on an energy-efficient electrophoretic mixing method capable of nearly eliminating CaSO4 and silicate scaling on electrically conducting membrane distillation (ECMD) membranes. The ECMD membrane material is composed of a percolating layer of carbon nanotubes deposited on porous polypropylene support and cross-linked by poly(vinyl alcohol). The application of low alternating potentials (2 Vpp,1Hz) had a dramatic impact on scale formation, with the impact highly dependent on the frequency of the applied signal, and in the case of silicate, on the pH of the solution

Desalinating a real hyper-saline pre-treated produced water via direct-heat vacuum membrane distillation.

Membrane distillation (MD) is an emerging thermal desalination technology capable of desalinating waters of any salinity. During typical MD processes, the saline feedwater is heated and acts as the thermal energy carrier; however, temperature polarization (as well as thermal energy loss) contributes to low distillate fluxes, low single-pass water recovery and poor thermal efficiency. An alternative approach is to integrate an extra thermal energy carrier as part of the membrane and/or module assembly, which can channel externally provided heat directly to the membrane-feedwater interface and/or along the feed channel length. This direct-heat delivery has been demonstrated to increase single-pass water recovery and enhance the overall thermal efficiency. We developed a bench-scale direct-heated vacuum MD (DHVMD) process to desalinate pre-treated oil and gas "produced water" with an initial total dissolved solids of 115,500&nbsp;ppm at a feed temperature ranging between 24 and 32&nbsp;°C. We evaluated both water flux and specific energy consumption (SEC) as a function of water recovery. The system achieved a 50% water recovery without significant scaling, with an average flux &gt;6&nbsp;kg m-2 hr-1 and a SEC as low as 2,530&nbsp;kJ kg-1. The major species of mineral scales (i.e., NaCl, CaSO4, and SrSO4) that limited the water recovery to 68% were modeled in terms of thermodynamics and identified by scanning electron microscopy and energy-dispersive X-ray spectroscopy. In addition, we further developed and employed a physics-based process model to estimate temperature, salinity, water transport and energy flows for full-scale vacuum MD and DHVMD modules. Model results show that a direct-heat input rate of 3,600&nbsp;W can increase single-pass water recovery from 2.1% to 3.1% while lowering the thermal SEC from 7,800&nbsp;kJ kg-1 to 6,517&nbsp;kJ kg-1 in an unoptimized module. Finally, the scaling up potential of DHVMD process is briefly discussed