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Highlights • The flux of multivalent cations across non-selective CMX membranes was 1.4 times > sodium. • A CMX-S membrane at the cathode boundary reduced the flux of Ca, Mg, and Ba into the electrode rinse. • Ca, Mg and Ba interfered by blocking transfer sites on the CMX-S membrane at the cathode barrier. • Overall flux was improved by unblocking the CMX-S membrane with periodic polarity reversal. • Soluble Fe precipitated throughout the stack and within the diluate and concentrate tanks. Abstract Electrodialysis is an electrochemically driven membrane technology usually used for treating feed water containing several thousand mg/l total dissolved solids (TDS). This research investigated the use of conventional ED for the treatment of flowback water from shale gas hydraulic fracturing that contains up to tens of thousands of mg/l TDS and contain a mixture of multivalent cations. This paper discusses efforts to treat concentrated brines with electrodialysis and focuses on the mitigation of the detrimental effects of multivalent cations such as calcium, magnesium, barium, iron, and in the feedstock. A previous paper detailed the effects of calcium under defined lab conditions. The apparent calcium fouling (in and around) the electrode cells was mitigated by changing the single cathode chamber boundary membrane to a (CMX-S) that was more selective for monovalent cations. This paper covers efforts undertaken to mitigate problems associated with high concentrations of calcium, barium, iron, and magnesium. Four field samples of produced water from oil and gas operations in from the Marcellus shale formation (generally Pennsylvania, USA) and the Barnett shale formation (generally north central Texas, USA) were also tested. These results from field samples were similar to the results from lab defined tests. Mechanisms of process interference by the different multivalent cations appear different for each species. Calcium, magnesium, barium, and iron were preferentially transported from the diluate to the concentrate compared to sodium by a factor of about 1.4:1 on a charge basis resulting in a suppression of the flux of sodium to the concentrate. A single CMX-S membrane selective for monovalent cations was placed at the cathode barrier resulting in a reduced flux of calcium, magnesium and barium into the electrode rinse. However total ion flux was inhibited caused by apparent blockage of the cation transfer sites on the CMX-S membrane by the stagnant multivalent cations. A series of tests with periodic pulse polarity-reversal (anode and cathode reversed for a brief time) indicted the blockage by calcium and barium was immediately reversable, however, iron was more problematic and may have precipitated on membrane surfaces other than the cathode barrier. [ABSTRACT FROM AUTHOR]

State officials responsible for the regulation of hydraulic fracturing (fracking) operations used in the production of oil and gas resources will inevitably confront a key policy issue; that is, to what extent can statewide regulations be developed without reducing land use autonomy typically exercised by local officials? Most state regulators have historically recognized the economic importance of industry jobs and favor the adoption of uniform regulatory requirements even if these rules preempt local policymaking authority. Conversely, many local officials seek to preserve land use autonomy to provide a greater measure of protection for public health and environmental quality goals. This paper examines how public officials in three states--Colorado, Pennsylvania, and Texas--address the question of state control versus local autonomy through their efforts to shape fracking policy decisions. While local officials within Texas have succeeded in developing fracking ordinances with relatively little interference from state regulators, Colorado and Pennsylvania have adopted a tougher policy stance favoring the retention of preemptive oil and gas statutes. Key factors that account for between state differences in fracking policy decisions include the strength of home rule provisions, gubernatorial involvement, and the degree of local experience with industrial economic activities. [ABSTRACT FROM AUTHOR]

Explores the union wage effect achieved by the teachers' unions in Pennsylvania. Main requirements for interpreting salary variation across school districts as union rents; Two definitions of salary; Reason administrators in Texas are likely to have much more flexibility in hiring than in Pennsylvania where teachers' unions dictate at least to some extent, hiring and firing practices.

Background Acculturation to life in the United States is a known predictor of Hispanic drinking behavior. We compare the ability of 2 theoretical models of this effect-sociocultural theory and general stress theory-to account for associations between acculturation and drinking in a sample of Mexican Americans. Limitations of previous evaluations of these theoretical models are addressed using a broader range of hypothesized cognitive mediators and a more direct measure of acculturative stress. In addition, we explore nonlinearities as possible underpinnings of attenuated acculturation effects among men. Methods Respondents ( N = 2,595, current drinker N = 1,351) were interviewed as part of 2 recent multistage probability samples in a study of drinking behavior among Mexican Americans in the United States. The ability of norms, drinking motives, alcohol expectancies, and acculturation stress to account for relations between acculturation and drinking outcomes (volume and heavy drinking days) were assessed with a hierarchical linear regression strategy. Nonlinear trends were assessed by modeling quadratic effects of acculturation and acculturation stress on cognitive mediators and drinking outcomes. Results Consistent with previous findings, acculturation effects on drinking outcomes were stronger for women than men. Among women, only drinking motives explained acculturation associations with volume or heavy drinking days. Among men, acculturation was linked to increases in norms, and norms were positive predictors of drinking outcomes. However, adjusted effects of acculturation were nonexistent or trending in a negative direction, which counteracted this indirect normative influence. Acculturation stress did not explain the positive associations between acculturation and drinking. Conclusions Stress and alcohol outcome expectancies play little role in the positive linear association between acculturation and drinking outcomes, but drinking motives appear to at least partially account for this effect. Consistent with recent reports, these results challenge stress models of linear acculturation effects on drinking outcomes and provide (partial) support for sociocultural models. Inconsistent mediation patterns-rather than nonlinearities-represented a more plausible statistical description of why acculturation-drinking associations are weakened among men. [ABSTRACT FROM AUTHOR]

Reviews the art exhibit `The Splendor of Eighteenth-Century Rome,' at the Philadelphia Museum of Art through May 28, 2000 and at the Museum of Fine Arts in Houston, Texas through September 17, 2000.

Summer school makes an unlikely candidate for a bright spot in education reform during these difficult economic times. It occupies a long-held negative place in U.S. culture, prompting dread in the hearts of many former and current students. Summer school conjures up images of sitting in hot classrooms and receiving remedial instruction while others swim, play, and enjoy the bounties of summer vacation. It's often framed as punishment for poor academic performance, carrying a stigma for students and teachers that can result in low attendance and lackluster outcomes. It's no big surprise, then, that summer school is considered an afterthought by most school leaders and that it's often the first program they cut when school budgets are slashed. Yet despite the seemingly overwhelming obstacles, many urban districts are helping create a new vision of summer school that may transform teaching and learning. This is due in large part to the American Recovery and Reinvestment Act (ARRA) passed in 2009. This article focuses on the National Summer Learning Association which has been leading the charge for a new vision for summer school since 2008 and has been working closely with a growing network of 16 urban school districts committed to making summer school and summer learning an essential component of their education reform agenda. Through robust partnerships with local nonprofit partners, these districts leverage community resources and better engage students in different types of learning--while also keeping costs down. (Contains 2 endnotes.)