University of North Texas

About: University of North Texas is a education organization based out in Denton, Texas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 11866 authors who have published 26984 publications receiving 705376 citations. The organization is also known as: Fight, North Texas & UNT.

High affinity of dodecylbenzene sulfonate for layered double hydroxide and resulting morphological changes

Abstract: 2∶1 Mg∶Al layered double hydroxide (LDH) with dodecylbenzene sulfonate in the gallery has been successfully prepared by the anion exchange and direct precipitation methods, and characterized by XRD, FTIR, SEM, EDX and AA. The interlayer spacing is 3.05 nm, which is in good agreement with the value estimated from an anti-parallel packing model with interpenetrating chains. We observe a high affinity of this surfactant anion for LDH in anion exchange and competition, exceeding that of sulfate and comparable to that of carbonate, and attribute this to hydrophobic interactions. More interestingly, the organic–inorganic self-assembled aggregates exhibit novel morphologies. These include bar-like particles that are several micrometers in length and tens to hundreds of nanometers in diameter, and curved as well as the more usual platy sheets. Contact with dodecylbenzene sulfonate solution places a hydrophobic surface on the normally hydrophilic Mg2Al(OH)6·0.5CO32−–LDH, allowing for miscible blending of inorganic and organic components in composites. Dodecylbenzene sulfonate is taken up in preference to chloride or, surprisingly, sulfate, and partly displaces even carbonate on refluxing.

The Evolution of Normal Galaxy X-Ray Emission Through Cosmic History: Constraints from the 6 MS Chandra Deep Field-South

Abstract: This article presents measurements of the evolution of normal-galaxy X-ray emission from z ≈ 0-7 using local galaxies and galaxy samples in the ≈6 Ms Chandra Deep Field-South (CDF-S) survey.

Three-dimensional structure determination from a single view

Abstract: The ability to determine the structure of matter in three dimensions has profoundly advanced our understanding of nature. Traditionally, the most widely used schemes for three-dimensional (3D) structure determination of an object are implemented by acquiring multiple measurements over various sample orientations, as in the case of crystallography and tomography, or by scanning a series of thin sections through the sample, as in confocal microscopy. Here we present a 3D imaging modality, termed ankylography (derived from the Greek words ankylos meaning 'curved' and graphein meaning 'writing'), which under certain circumstances enables complete 3D structure determination from a single exposure using a monochromatic incident beam. We demonstrate that when the diffraction pattern of a finite object is sampled at a sufficiently fine scale on the Ewald sphere, the 3D structure of the object is in principle determined by the 2D spherical pattern. We confirm the theoretical analysis by performing 3D numerical reconstructions of a sodium silicate glass structure at 2 A resolution, and a single poliovirus at 2-3 nm resolution, from 2D spherical diffraction patterns alone. Using diffraction data from a soft X-ray laser, we also provide a preliminary demonstration that ankylography is experimentally feasible by obtaining a 3D image of a test object from a single 2D diffraction pattern. With further development, this approach of obtaining complete 3D structure information from a single view could find broad applications in the physical and life sciences.

The Humanistic Side of Eco-Industrial Parks: Champions and the Role of Trust

Abstract: Hewes A. K. and Lyons D. I. (2008) The humanistic side of eco-industrial parks: champions and the role of trust, Regional Studies. Two leading advocates of eco-industrial parks (EIPs), Valdemar Christensen and Peter Lowitt, participated in a qualitative research study focused on their role in developing EIPs in Ukraine and Massachusetts, USA, respectively. Christensen formerly championed industrial symbiosis in Kalundborg, Denmark, and Lowitt shepherded the process at the Londonderry EIP in New Hampshire, USA. Based on the empirical data collected from the methods of ethnography and grounded theory, a systematic analysis of champion behaviour revealed emergent themes that champions of EIPs emphasize social relationships as opposed to technological connections. The repeating themes of trust and community embeddedness, proximity and the importance of the champion to the long-term viability of the project were highlighted. The foundation of the Champions' success was the ability to establish humanistic conne...

Analysis of Establishing Operations for Self-Injury Maintained by Escape.

Abstract: Self-injurious behavior (SIB) can be maintained through negative reinforcement when, in the context of training or task requirements, it produces escape as a consequence. Several studies have demonstrated methods for identifying and treating SIB maintained by negative reinforcement; however, few analyses of the establishing operations associated with demand situations have been conducted. The current series of studies illustrates a method for identifying some establishing operations for escape by systematically altering certain dimensions of the demand context while maintaining an escape contingency for SIB. Dimensions assessed in these studies included task novelty, duration of instructional sessions, and rate of task presentation. Data indicate that these variables can have establishing properties for behavior maintained by escape. Implications of the results are discussed, as are potential refinements and extensions of the assessment procedures.