Developments in tracer flow testing for geothermal production engineering

The chemical tracer flow test (TFT) technique for two-phase mass flow rate measurement has been in use since 1992 and is now employed routinely in the major geothermal fields of 6 countries. There have been continuous refinements in the TFT process over time, including introduction of new vapor and liquid tracers, and upgraded tracer metering equipment. Since TFT is now used by many operators around the world, it is important to ensure that the technique is consistent and robust, and not site-specific or sensitive to small deviations in methodology. Comparative data are presented for some of the various tracers, including recent tests on alcohol tracers. These tests show sulfur hexafluoride (SF₆) is the most versatile and accurate tracer for TFT steam measurements, while alcohol can be used in limited applications. Sodium benzoate remains the primary liquid-phase tracer, but recent tests using naphthalene sulfonic acids (NSA) look very promising. The SF₆ and NSA tracers allow miniaturization of the tracer metering equipment, resulting in greater portability and lower cost.     

Women, men, work, and family.

The lives of women and men, the relationships that they establish, and their work have changed dramatically in the past 50 years, but the dominant theories driving research in these areas have not. In this article, the authors argue that the facts underlying the assumptions of the classical theories of gender and multiple roles have changed so radically as to make the theories obsolete. Moreover, a large body of empirical data fails to support the predictions flowing from these theories. Yet the development of new theory for guiding research and clinical practice has not kept pace. The authors attempt to fill this theoretical gap by reviewing the research literature and articulating an expansionist theory of gender, work, and family that includes four empirically derived and empirically testable principles better matched to today's realities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Longitudinal change in language production: Effects of aging and dementia on grammatical complexity and propositional content.

Mixed modeling was used to examine longitudinal changes in linguistic ability in healthy older adults and older adults with dementia. Language samples, vocabulary scores, and digit span scores were collected annually from healthy older adults and semiannually from older adults with dementia. The language samples were scored for grammatical complexity and propositional content. For the healthy group, age-related declines in grammatical complexity and propositional content were observed. The declines were most rapid in the mid 70s. For the group with dementia, grammatical complexity and propositional content also declined over time, regardless of age. Rates of decline were uniform across individuals. These analyses reveal how both grammatical complexity and proposition content are related to late-life changes in cognition in healthy older adults as well as those with dementia. Alzheimer's disease accelerates this decline, regardless of age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Internet Distance Learning: The Problems, the Pitfalls, and the Future

The Georgia Institute of Technology in Atlanta is in a unique position of having a campus located in the heart of the Lorraine region of France in the city of Metz. Since the number of faculty at GTL is limited, some courses must be offered in non-traditional formats. Due to the problems involved in shipping video tapes across the Atlantic, the Internet was considered as an alternative delivery vehicle. Initially driven by a very real and pressing need to deliver courses in a timely and effective manner across the Atlantic, Internet course delivery is now finding its way into many other programs at Georgia Tech. In this paper, we describe some of our experiences with Internet course development and delivery, and present a set of tools that we have developed for placing courses on the web easily. We will also present some of the problems and limitations with on-line course production and delivery, and speculate on the future of distance education.     

Sterol ester production using lipase-catalyzed reactions in supercritical carbon dioxide

Synthesis of sterol and stanol esters is of importance, due to their recent recognition and application in the food and nutriceutical industries as cholesterol-lowering agents. In this study, several enzymes were evaluated to determine the best catalyst and optimal conditions for the reaction between various fatty acids and cholesterol or sitostanol in supercritical carbon dioxide (SC-CO₂). Using an analytical supercritical fluid extraction (SFE) unit, the lipase derived from Burkholderia cepacia, Chirazyme L-1, was determined to be the most selective for facilitating the desired reactions. Fatty acids C₈-C₁₈, pressures between 20.7 MPa and 31 MPa, a temperature range of 40-60 °C, along with variable flow rates, and initial static hold times were used to evaluated the feasibility of the above reaction. The yield of the cholesterol esters, as measured by supercritical fluid chromatography (SFC), ranged from 90% for caprylic acid to 99% for palmitic acid, while the corresponding reaction between sitostanol and the same fatty acids produced yields of 92% for caprylic acid and 99% for palmitic acid, respectively. The extraction apparatus was modified to provide a continuous flow of the reagent fatty acid and sterol/stanol over the enzyme bed, thereby allowing continuous production of the desired esters which averaged a 99% yield under optimal conditions.     

Supervisor countertransference: A qualitative investigation into its identification and description.

Interviews were conducted with 11 psychotherapy supervisors about an experience of supervisor countertransference with a predoctoral intern. On the basis of a qualitative analysis, results revealed that supervisor countertransference manifestations consisted of affective (e.g., emotional distress), cognitive (e.g., questioning one's own competence), and behavioral (e.g., disengagement) components. Sources of supervisor countertransference always included both the intern's interpersonal style and the supervisor's unresolved personal issues and at times pertained to intern–supervision environment interactions, problematic client–intern interactions, intern–supervisor interactions, and supervisor–supervision environment interactions. Supervisors typically believed their supervisor countertransference initially weakened but eventually strengthened the supervisory relationship. Most supervisors managed their supervisor countertransference reaction by talking with colleagues, and most acknowledged they had received little or no training in addressing supervisor countertransference issues with trainees. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Therapist homophobia, client sexual orientation, and source of client HIV infection as predictors of therapist reactions to clients with HIV.

Four hundred twenty-five psychologists received vignettes depicting a male client who was either gay or heterosexual and whose source of HIV infection was sexual contact, a blood transfusion, intravenous drug use, or unspecified. Respondents' homophobia and reactions to the client in the vignette were measured. Canonical correlation analyses revealed that therapist attributions of client responsibility for problem cause were predicted by the source of HIV infection and therapist homophobia. In addition, therapists responded with less empathy, attributed less responsibility to the client for solving his problems, assessed the client's functioning to be worse, and were less willing to work with the client when the client's source of HIV infection was other than drugs, when the client was gay, and when therapists were more homophobic. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimizing size and distribution of voids in phenolic resins through the choice of catalyst types

Phenolics are widely used for over a century in different industries due to their chemical resistance and thermomechanical properties. However, the presence of voids in phenolic resins has negative effects on the mechanical properties and a conventional approach is to avoid these by utilizing very long cure cycles. Our alternative approach investigates the tailoring of void size and distribution to achieve a better balance between processing time and mechanical properties. Therefore, we produced phenolic resin with a void-free microstructure by a long cure cycle as a reference. To alter the void size and distributions, we utilized different catalysts and a short cure cycle to obtain phenolic resins and test their flexural properties with respect to the reference. We investigated the fracture surfaces of all materials by SEM, FTIR and compared results to finite element modeling that confirmed the effects of different void size and distributions on the mechanical properties. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48249.     

Evaluating Four Storm-Water Performance Metrics with a North Carolina Coastal Plain Storm-Water Wetland

Storm-water best management practices (BMPs) are typically assessed using the performance metric of pollutant concentration removal efficiencies. However, debate exists whether this is the most appropriate metric to use. In this study, a storm-water wetland constructed and monitored in the coastal plain of North Carolina is evaluated for water quality and hydrologic performance using four different metrics: concentration reduction, load reduction, comparison to nearby ambient water quality monitoring stations, and comparison to other wetlands studied in North Carolina. The River Bend storm-water wetland was constructed in spring 2007 and was monitored from June 2007 through May 2008. Twenty-four hydrologic and 11 water quality events were captured and evaluated. The wetland reduced peak flows and runoff volumes by 80 and 54%, respectively. Reductions were significant. Concentrations for the following pollutants increased: total kjeldahl nitrogen (TKN), NH4–N, total nitrogen (TN), and total suspended solids (TSS); inflow and outflow concentrations did not change for total phosphorus (TP), while only NO2–3–N and orthophosphorus (OP) concentrations were lower at the outlet. Using a load reduction metric, results were strikingly different, showing positive load reductions of 35, 41, 42, 36, 47, 61, and 49% for these respective pollutants: TKN, NO2–3–N, NH4–N, TN, TP, OP, and TSS. When comparing the effluent concentrations from the wetland to ambient water quality in the Trent River, all effluent nitrogen species concentration were either similar or lower. TP and TSS concentrations leaving the wetland were higher than ambient water quality data. Finally, by comparing pollutant concentrations among different North Carolina wetlands, it is apparent the River Bend wetland received relatively “clean” water and released water with pollutant concentrations comparable to all other studies examined. Major conclusions from this study include: (1) storm-water wetlands sited in sandier soils (such as those of the North Carolina coastal plain) should be considered a low impact development tool and (2) the selection of performance metric has a pronounced bearing on how a BMP’s performance is perceived. Sole reliance on a concentration reduction metric is discouraged.     

Analysis of Product Morphologies and Reaction Mechanisms on Gaseous Reduction of Iron Oxides

It is well established that in gaseous reduction processes solid iron oxides exhibit a wide range of reducibilities. Using the interface stability criteria developed to describe the decomposition of metal compounds in reactive gas atmospheres, together with microstructural evidence obtained under well characterised reaction conditions, the relationships between product structures, and the mechanisms and the kinetics of reduction of iron oxides have been examined. It is shown that the structures and reaction rates can be explained through the occurrence of four principal mechanisms; continuous gas pore formation, dense metal layer growth, discontinuous metal layer breakdown and continuous coupled growth of metal and pores. Through identification of the critical conditions for these different mechanisms, the maximum rates of reduction of a given starting material as a function of temperature, thermal history and gas conditions can be more clearly understood.