Surface Modification of Ready-to-Use Hollow Fiber Ultrafiltration Modules for Oil/Water Separation

Reusing wastewater from oil-related industries is becoming increasingly important, especially in water-stressed oil-producing countries. Before oily wastewater can be discharged or reused, it must be properly treated, e.g., by membrane-based processes like ultrafiltration. A major issue of the applied membranes is their high fouling propensity. This paper reports on mitigating fouling inside ready-to-use ultrafiltration hollow-fiber modules used in a polishing step in oil/water separation. For this purpose, in-situ polyzwitterionic hydrogel coating was applied. The membrane performance was tested with oil nano-emulsions using a mini-plant system. The main factors influencing fouling were systematically investigated using statistical design of experiments.     

Investment optimization model for freshwater acquisition and wastewater handling in shale gas production

Major challenges of water use in the drilling and fracturing process in shale gas production are large volumes required in a short‐period of time and the nonsteady nature of wastewater treatment. A new mixed‐integer linear programming (MILP) model for optimizing capital investment decisions for water use for shale gas production through a discrete‐time representation of the State‐Task Network is presented. The objective is to minimize the capital cost of impoundment, piping, and treatment facility, and operating cost including freshwater, pumping, and treatment. The goal is to determine the location and capacity of impoundment, the type of piping, treatment facility locations and removal capability, freshwater sources, as well as the frac schedule. In addition, the impact of several factors such as limiting truck hauling and increasing flowback volume on the solution is examined. A case study is optimized to illustrate the application of the proposed formulation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1770–1782, 2015     

The minor third communicates sadness in speech, mirroring its use in music.

There is a long history of attempts to explain why music is perceived as expressing emotion. The relationship between pitches serves as an important cue for conveying emotion in music. The musical interval referred to as the minor third is generally thought to convey sadness. We reveal that the minor third also occurs in the pitch contour of speech conveying sadness. Bisyllabic speech samples conveying four emotions were recorded by 9 actresses. Acoustic analyses revealed that the relationship between the 2 salient pitches of the sad speech samples tended to approximate a minor third. Participants rated the speech samples for perceived emotion, and the use of numerous acoustic parameters as cues for emotional identification was modeled using regression analysis. The minor third was the most reliable cue for identifying sadness. Additional participants rated musical intervals for emotion, and their ratings verified the historical association between the musical minor third and sadness. These findings support the theory that human vocal expressions and music share an acoustic code for communicating sadness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impact of Particle Generation Method on the Apparent Hygroscopicity of Insoluble Mineral Particles

Calcite (CaCO ₃ ) mineral particles are commonly generated by atomization techniques to study their heterogeneous chemistry, hygroscopicity, and cloud nucleation properties. Here we investigate the significant artifact introduced in generating calcium mineral particles through the atomization of a saturated suspension of the powder in water, by measuring particle hygroscopicity via CCN activation curves. Particles produced from atomization displayed hygroscopicities as large as κ_app > 0.1, 100 times more hygroscopic than that obtained for dry-generated calcite, κ_app = 0.0011. The hygroscopicity of the wet-generated particles increased as a function of time the calcite powder spent in water, and with decreasing particle size. Wet-generated calcium oxalate was more hygroscopic through wet- (κ_app = 0.34) versus dry-generation (κ_app = 0.048). Atomized calcium sulfate particles, however, were only slightly more hygroscopic (κ_app = 0.0045) than those generated dry (κ_app = 0.0016). Single-particle analysis by ATOFMS and SEM/EDX, and bulk analysis of the calcite powders by ICP-MS and IC revealed no significant soluble contaminants. The atomized particles were likely composed of components that dissolved from the powder and then re-precipitated, and appeared to contain little of the original mineral powder. The increased hygroscopicity of atomized calcite may have been caused by aqueous carbonate chemistry producing Ca(OH) ₂ , Ca(HCO ₃ ) ₂ , and metastable hydrates with increased solubility. Surface water adsorption may have also played a role, in addition to uncharacterized soluble components produced by wet-generation, and the precipitation of amorphous phases including glassy states. This study suggests that using wet-generation methods to suspend mineral dust samples will not produce particles with the correct physicochemical properties in laboratory studies, a finding which has important implications for past and future laboratory studies focusing on understanding relationships between the hygroscopicity and chemistry of mineral dust particles.     

Modeling longitudinal data from a rolling therapy group program with membership turnover: Does group culture affect individual alliance?

Many community- and hospital-based group treatment programs have an open enrolment, that is, a rolling admissions structure, in which a group member who drops out or successfully completes therapy is replaced by another individual. Although practically efficient and perhaps clinically useful, the interdependence of these group participants' data may result in incorrect inferences drawn from the data analyses if this interdependence is not accounted for. We present an analytic strategy that uses time varying covariates in multilevel models to illustrate a methodology to address these data analysis problems. Participants were adults with eating disorders (N = 229) who attended an average of 12 weeks of a rolling admissions group-based day hospital program during an 8-year period, and who completed a group therapy alliance measure weekly. Individual alliance to the group increased from week to week, and this growth remained significant even after controlling for the time varying level of other group members' alliance to the group. Further, the level of an individual's alliance score during any given week was positively related to the group's alliance during that week. The multilevel time varying covariate models presented here add to a very small but emerging set of analytic strategies available for researchers to address some of the hurdles to correctly analyze data from rolling admissions group-based treatment programs. Results from this study provide evidence that a group's culture is passed on and affects an individual's alliance to the group despite changes in group membership. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Approach for measuring the chemistry of individual particles in the size range critical for cloud formation

Aerosol particles, especially those ranging from 50 to 200 nm, strongly impact climate by serving as nuclei upon which water condenses and cloud droplets form. However, the small number of analytical methods capable of measuring the composition of particles in this size range, particularly at the individual particle level, has limited our knowledge of cloud condensation nuclei (CCN) composition and hence our understanding of aerosols effect on climate. To obtain more insight into particles in this size range, we developed a method which couples a growth tube (GT) to an ultrafine aerosol time-of-flight mass spectrometer (UF-ATOFMS), a combination that allows in situ measurements of the composition of individual particles as small as 38 nm. The growth tube uses water to grow particles to larger sizes so they can be optically detected by the UF-ATOFMS, extending the size range to below 100 nm with no discernible changes in particle composition. To gain further insight into the temporal variability of aerosol chemistry and sources, the GT-UF-ATOFMS was used for online continuous measurements over a period of 3 days.     

Physicochemical determinants of multiwalled carbon nanotube bacterial cytotoxicity

Rational modification of carbon nanotubes (CNTs) to isolate their specific physical and chemical properties will inform a mechanistic understanding of observed CNT toxicity in bacterial systems. The present study compares the toxicity of commercially obtained multiwalled carbon nanotubes (MWNTs) before and after physicochemical modification via common purification and functionalization routes, including dry oxidation, acid treatment functionalization, and annealing. Experimental results support a correlation between bacterial cytotoxicity and physicochemical properties that enhance MWNT-cell contact opportunities. For example, we observe higher toxicity when the nanotubes are uncapped, debundled, short, and dispersed in solution. These conclusions demonstrate that physicochemical modifications of MWNTs alter their cytotoxicity in bacterial systems and underline the need for careful documentation of physical and chemical characteristics when reporting the toxicity of carbon-based nanomaterials.     

Defining University Anchor Institution Strategies: Comparing Theory to Practice

Since the 1990s, some urban universities have served as neighborhood anchors with an interest in revitalization. Current theory suggests anchors adopt ‘shared value’ approaches, leveraging resources for mutually beneficial improvement in the community. This study explores assumptions in contemporary anchor frameworks and uses a survey to examine how 22 U.S. universities approach their roles as anchor institutions. The study finds that the universities tend to prioritize place-based initiatives, while contemporary frameworks are more normative and highlight socioeconomic practices. Based on reported strategies, the author proposes an alternate typology that accounts for the ways universities most commonly describe anchor approaches, complementing contemporary theory.     

Geochemical cycling of arsenic in a coastal aquifer

Biogeochemically modified pore waters from subterranean estuaries, defined as the mixing zone between freshwater and saltwater in a coastal aquifer, are transported to coastal waters through submarine groundwater discharge (SGD). SGD has been shown to impact coastal and perhaps global trace metal budgets. The focus of this study was to investigate the biogeochemical processes that control arsenic cycling in subterranean estuaries. Total dissolved As, as well as a suite of other trace metals and nutrients, were measured in a series of wells and sediment cores at the head of Waquoit Bay, MA. Dissolved As ranged from below detection to 9.5 microg/kg, and was associated with plumes of dissolved Fe, Mn, and P in the groundwater. Sedimentary As, ranging from 360 to 7500 microg/kg, was highly correlated with sedimentary Fe, Mn, and P. In addition, amorphous Fe (hydr)oxides were more efficient scavengers of dissolved As than the more crystalline forms of solid-phase Fe. Given that dissolved As in the surface bay water was lower than within the subterranean estuary, our results indicate that the distribution and type of Fe and Mn (hydr)oxides in coastal aquifers exert a major influence on the biogeochemical cycling of As in subterranean estuaries and, ultimately, the fate of groundwater-derived As in marine systems influenced by SGD.