Aviation-Related Impacts on Ultrafine Particle Number Concentrations Outside and Inside Residences near an Airport.

Jet engine exhaust is a significant source of ultrafine particles and aviation-related emissions can adversely impact air quality over large areas surrounding airports. We investigated outdoor and indoor ultrafine particle number concentrations (PNC) from 16 residences located in two study areas in the greater Boston metropolitan area (MA, USA) for evidence of aviation-related impacts. During winds from the direction of Logan International Airport, that is, impact-sector winds, an increase in outdoor and indoor PNC was clearly evident at all seven residences in the Chelsea study area (∼4-5 km from the airport) and three out of nine residences in the Boston study area (∼5-6 km from the airport); the median increase during impact-sector winds compared to other winds was 1.

Ultrabright fluorescent silica particles with a large number of complex spectra excited with a single wavelength for multiplex applications.

We report on a novel approach to synthesize ultrabright fluorescent silica particles capable of producing a large number of complex spectra. The spectra can be excited using a single wavelength which is paramount in quantitative fluorescence imaging, flow cytometry and sensing applications. The approach employs the physical encapsulation of organic fluorescent molecules inside a nanoporous silica matrix with no dye leakage.

Self-assembly of multi-hierarchically structured spongy mesoporous silica particles and mechanism of their formation.

Here we report on self-assembly of novel multi-hierarchically structured meso(nano)porous colloidal silica particles which have cylindrical pores of 4-6nm, overall size of ∼10μm and "cracks" of 50-200nm. These cracks make particles look like micro-sponges. The particles were prepared through a modified templated sol-gel self-assembly process.

Control and formation mechanism of extended nanochannel geometry in colloidal mesoporous silica particles.

A large class of colloidal multi-micron mesoporous silica particles have well-defined cylindrical nanopores, nanochannels which self-assembled in the templated sol-gel process. These particles are of broad interest in photonics, for timed drug release, enzyme stabilization, separation and filtration technologies, catalysis, etc. Although the pore geometry and mechanism of pore formation of such particles has been widely investigated at the nanoscale, their pore geometry and its formation mechanism at a larger (extended) scale is still under debate.

Health Effects and Environmental Justice Concerns of Exposure to Uranium in Drinking Water.

We discuss the recent epidemiologic literature regarding health effects of uranium exposure in drinking water focusing on the chemical characteristics of uranium. While there is strong toxicologic evidence for renal and reproductive effects as well as DNA damage, the epidemiologic evidence for these effects in people exposed to uranium in drinking water is limited. Further, epidemiologic evidence is lacking for cardiovascular and oncogenic effects.

Silk Fibroin Degradation Related to Rheological and Mechanical Properties.

Regenerated silk fibroin has been proposed as a material substrate for biomedical, optical, and electronic applications. Preparation of the silk fibroin solution requires extraction (degumming) to remove contaminants, but results in the degradation of the fibroin protein. Here, a mechanism of fibroin degradation is proposed and the molecular weight and polydispersity is characterized as a function of extraction time.

Development and application of a screening model for evaluating bioenhanced dissolution in DNAPL source zones.

In-situ bioremediation, a widely applied treatment technology for source zones contaminated with dense non-aqueous phase liquids (DNAPLs), has proven economical and reasonably efficient for long-term management of contaminated sites. Successful application of this remedial technology, however, requires an understanding of the complex interaction of transport, mass transfer, and biotransformation processes. The bioenhancement factor, which represents the ratio of DNAPL mass transfer under microbially active conditions to that which would occur under abiotic conditions, is commonly used to quantify the effectiveness of a particular bioremediation remedy.

Modeling coupled nanoparticle aggregation and transport in porous media: a Lagrangian approach.

Changes in nanoparticle size and shape due to particle-particle interactions (i.e., aggregation or agglomeration) may significantly alter particle mobility and retention in porous media.

Spatial and temporal differences in traffic-related air pollution in three urban neighborhoods near an interstate highway.

Relatively few studies have characterized differences in intra- and inter-neighborhood traffic-related air pollutant (TRAP) concentrations and distance-decay gradients in along an urban highway for the purposes of exposure assessment. The goal of this work was to determine the extent to which intra- and inter-neighborhood differences in TRAP concentrations can be explained by traffic and meteorology in three pairs of neighborhoods along Interstate 93 (I-93) in the metropolitan Boston area (USA). We measured distance-decay gradients of seven TRAPs (PNC, pPAH, NO, NO, BC, CO, PM) in near-highway (<400 m) and background areas (>1 km) in Somerville, Dorchester/South Boston, Chinatown and Malden to determine whether (1) spatial patterns in concentrations and inter-pollutant correlations differ between neighborhoods, and (2) variation within and between neighborhoods can be explained by traffic and meteorology.

Mathematical modeling of the transport and dissolution of citrate-stabilized silver nanoparticles in porous media.

A one-dimensional mathematical model is developed and implemented to describe the coupled transport of citrate-stabilized silver nanoparticles (nAg) and dissolved silver ions in porous media. This hybrid numerical simulator employs an Eulerian finite difference (FD) method to model the reactive transport of dissolved constituents and a Lagrangian (random-walk particle-tracking (RWPT)) approach to capture the transport and differential aging of nanoparticles. Model performance is demonstrated by comparison of simulations with data obtained from a series of nAg transport and dissolution column experiments.

Transport behavior of functionalized multi-wall carbon nanotubes in water-saturated quartz sand as a function of tube length.

A series of one-dimensional column experiments was conducted to examine the effects of tube length on the transport and deposition of 4-ethoxybenzoic acid functionalized multi-wall carbon nanotubes (MWCNTs) in water-saturated porous media. Aqueous MWCNTs suspensions were prepared to yield three distributions of tube lengths; 0.02-1.

Transport and retention of fullerene nanoparticles in natural soils.

Commercial production and use of fullerene (C60) nanomaterials will inevitably lead to their release into the environment, where knowledge of C60 fate and transport is limited. In this study, a series of one-dimensional column experiments was conducted to assess the transport and retention of nanoscale fullerene aggregates (nC60) in water-saturated soils. Under the experimental conditions, complete retention of nC60 was observed in columns (2.

The Vida Verde Women's Co-Op: Brazilian immigrants organizing to promote environmental and social justice.

We reviewed the key steps in the launch of the Vida Verde Women's Co-Op among Brazilian immigrant housecleaners in Somerville, MA. The co-op provides green housecleaning products, encourages healthy work practices, and promotes a sense of community among its members. We conducted in-depth interviews with 8 of the first co-op members, who reported a reduction in symptoms associated with the use of traditional cleaning agents and a new sense of mutual support.

Development of risk maps to minimize uranium exposures in the Navajo Churchrock mining district.

Background: Decades of improper disposal of uranium-mining wastes on the Navajo Nation has resulted in adverse human and ecological health impacts as well as socio-cultural problems. As the Navajo people become increasingly aware of the contamination problems, there is a need to develop a risk-communication strategy to properly inform tribal members of the extent and severity of the health risks. To be most effective, this strategy needs to blend accepted risk-communication techniques with Navajo perspectives such that the strategy can be used at the community level to inform culturally- and toxicologically-relevant decisions about land and water use as well as mine-waste remediation.

Can surgeons think and operate with haptics at the same time?

Much effort has been devoted to incorporating haptic feedback into surgical simulators. However, the benefits of haptics for novice trainees in the early stages of learning are not clear. Presumably, novices have less spare attentional resources to attend to haptic cues while learning basic laparoscopic skills.

The impact of temperature and gas-phase oxygen on kinetics of in situ ammonia removal in bioreactor landfill leachate.

Microcosm experiments aimed at defining a rate equation that describes how different environmental conditions (i.e., gas-phase oxygen concentrations, temperature and ammonia concentration) may impact in situ ammonia removal were conducted.