Theory of phase segregation in DNA assemblies containing two different base pair sequence types

Spontaneous pairing of homologous DNA sequences – a challenging subject in molecular biophysics, often referred to as ‘homology recognition’ – ha s been observed in vitro for several DNA system s a . One of th e se experiments involved liquid crystalline quasi - columnar phases formed by a mixture of two kinds of oligo mer of double stranded DNA . Both oligomer types were of the same length and identical stoichiometric base - pair composition , but the base - pairs followed a different order . Phase segregation of the two DNA types was observed in the experiments , wit h the formation of boundaries between domai ns rich in molecules of one type (order) of base pair sequence . We formulate here a modified ‘ X - Y model ’ for phase segregation in such assemblies , obtain approximate solutions of the model , compare analytical results to Monte Carlo simulations, and rationalize past experimental observations . This study, furthermore , reveals the factors that affect the degree of segregat ion . Such information c ould be used in planning new versions of similar segregation experiments , needed for deepen i ng our understanding of forces that might be involved , e.g., in gene - gene recognition

Investigation of the applicability of using the triple redundant hydrogen sensor for methane sensing

Application specifications for the methane sensor were assembled and design guidelines, development goals and evaluation criteria were formulated. This was done to provide a framework to evaluate sensor performance and any design adjustments to the preprototype sensor that could be required to provide methane sensitivity. Good response to hydrogen was experimentally established for four hydrogen sensor elements to be later evaluated for methane response. Prior results were assembled and analyzed for other prototype hydrogen sensor performance parameters to form a comparison base. The four sensor elements previously shown to have good hydrogen response were experimentally evaluated for methane response in 2.5% methane-in-air. No response was obtained for any of the elements, despite the high methane concentration used (50% of the Lower Flammability Limit). It was concluded that the preprototype sensing elements were insensitive to methane and were hydrogen specific. Alternative sensor operating conditions and hardware design changes were considered to provide methane sensitivity to the preprototype sensor, including a variety of different methane sensing techniques. Minor changes to the existing sensor elements, sensor geometry and operating conditions will not make the preprototype hydrogen sensor respond to methane. New sensor elements that will provide methane and hydrogen sensitivity require replacement of the existing thermistor type elements. Some hydrogen sensing characteristics of the modified sensor will be compromised (larger in situ calibration gas volume and H2 nonspecificity). The preprototype hydrogen sensor should be retained for hydrogen monitoring and a separate methane sensor should be developed

A Thematic Analysis of Local Respondents\u27 Perceptions of Barnett Shale Energy Development

Researchers have found that the economic, social, and environmental impacts of energy development vary with both the type and location of development. Previous studies have highlighted impacts associated with the conventional energy development that occurred in the western United States in the 1970s and 1980s, and with offshore oil drilling in the Gulf of Mexico. Recently, however, unconventional natural gas development has become a more common type of energy development, the impacts of which are not yet well understood. To assess these impacts, as part of a larger quantitative study conducted within two Texas counties, survey respondents were invited to share “additional comments” as desired. I analyzed these comments using open coding and constant comparison to identify prominent themes for each county. Themes ranged from positive to negative, and reflected economic, social, and environmental impacts accompanying unconventional natural gas development. Findings may inform theory and be of interest to community leaders and others interested in the impacts of unconventional gas development

Iodine generator for reclaimed water purification

The system disclosed is for controlling the iodine level in a water supply in a spacecraft. It includes an iodine accumulator which stores crystalline iodine, an electrochemical valve to control the input of iodine to the drinking water and an iodine dispenser. A pump dispenses fluid through the iodine dispenser and an iodine sensor to a potable water tank storage. The iodine sensor electronically detects the iodine level in the water, and through electronic means, produces a correction current control. The correction current control operates the electro-chemical iodine valve to release iodine from the iodine accumulator into the iodine dispenser

Aircrew oxygen system

Closed-loop rebreather system which includes pilot provides oxygen for use in aircraft by safe, reliable method of low weight and size and reduces expense of ground equipment. Water electrolysis generated oxygen is fed into rebreather loop which allows nitrogen elimination and water and carbon dioxide removal

Attaining Sustainable Behavior among Non-environmentally-motivated Individuals: A Formative Experiment

Experts agree that overconsumption is a major problem in Western culture today, particularly in the United States. Thus, it is important to promote sustainable behavior among the general public. And yet, existing educational programming geared toward promoting such behavior changes remains appealing largely to environmentally-motivated audiences, as opposed to individuals with alternative (i.e., social and economic) motivations. In response to this discrepancy, I conducted a formative experiment with the goals of: 1) fostering participation among non-environmentally-motivated individuals in sustainable living educational programming; and 2) obtaining behavior change commitments, in the direction of more sustainable lifestyles, from those participants. As part of the formative process, I conducted four sequential iterations of my chosen intervention. That intervention consisted not only of the presentation of an existing curriculum designed to promote sustainable living, but also of the process of organization selection, key informant involvement, participant recruitment, and program evaluation. In order to evaluate and improve levels of goal achievement within the study, I used multiple data sources, including: key informant interviews, survey questionnaires, and qualitative observations. Those data sources contained measures of numerous constructs, which were used to: provide a deep understanding of the context of the study; evaluate the outcomes of the project\u27s four iterations; identify and overcome enhancing and inhibiting factors that may have affected goal achievement; and define the scope of the findings. Across four iterations of the intervention, levels of goal achievement improved as adaptations were made to various aspects of the intervention (i.e., the processes of organization selection, key informant involvement, participant recruitment, and program evaluation). The outcomes obtained suggested the value, within the study context, of targeting and collaborating with faith-based and faith-affiliated organizations in the effort to promote sustainable behavior at the individual level. Recommendations for effectively working with such groups, as informed by my findings, include: acknowledging and overcoming existing perceptions of terminology such as sustainability and sustainable living; recognizing and appealing to existing values, priorities, and motivations among target audiences and participants; and utilizing personal influence, leadership involvement, and word of mouth promotion to secure participation at all stages of a given intervention

Iodine generator for disinfecting reclaimed water

System dispenses iodine into water tank automatically in quantities varying from 0.5 to 20 ppm. It stores 180-day supply of iodine crystals, sufficient to support six people consuming water at rate of 4.5 to 13.6 kg per person per day

Promoting Participation in Sustainable Living Educational Programming Events Among Nonenvironmentally-Motivated Individuals: The Importance of Key Informant Involvement

Many social science researchers agree that overconsumption of resources and consumer goods is a major problem in Western culture today, particularly in the United States. Thus, promoting sustainable behavior among the public in rural and urban areas alike is important. Although existing research offers suggestions for promoting sustainable behaviors among environmentally-motivated audiences, a void remains with respect to encouraging non-environmentally-motivated individuals to adopt more sustainable behaviors. In response, I conducted a formative experiment aimed specifically at: 1) fostering participation among non-environmentally motivated individuals in sustainable living educational programming events, and 2) promoting subsequent behavior change among those participants in the direction of more sustainable lifestyles. This article focuses on the first goal, and specifically on the role of key informant involvement in achieving increasing levels of participation for each of the four iterations comprising this project. This strategy has the potential to improve participation in similar programming among various target audiences, including those in the rural areas familiar to JRSS readership

One-man, self-contained CO2 concentrating system

A program to design, fabricate, and test a 1-man, self-contained, electrochemical CO2 concentrating system is described. The system was designed with electronic controls and instrumentation to regulate performance, to analyze and display performance trends, and to detect and isolate faults. Ground support accessories were included to provide power, fluids, and a Parametric Data Display allowing real time indication of operating status in engineering units

Fractional capacity electrolyzer development for CO2 and H2O electrolysis

The electrolyzer module was designed to produce 0.24 kg/d (0.53 lb/d) of breathable oxygen from the electrolysis of metabolic carbon dioxide and water vapor. The fractional capacity electrolyzer module is constructed from three electrochemical tube cells and contains only three critical seals. The module design illustrated an 84 percent reduction in the total number of seals for a one person capacity oxygen generating system based on the solid electrolyte carbon dioxide and water vapor electrolysis concept. The electrolyzer module was successfully endurance tested for 71 days