Mechanisms of nonstoichiometry in HfN_1-<i>x</i>

Density functional theory is used to calculate defect structures that can accommodate nonstoichiometry in hafnium nitride: HfN1-x, 0 ≤ X ≤ 0.25. It is predicted that a mechanism assuming simple distributions of nitrogen vacancies can accurately describe the variation in the experimentally observed lattice parameter with respect to the nitrogen nonstoichiometry. Although the lattice parameter changes are remarkably small across the whole nonstoichiometry range, the variations in the bulk modulus are much greater

Remembering The Church In The Wildwood: The Archival Processing And Digitization Of The Martinsville Baptist Church Collection

Martinsville Baptist Church was founded in 1912 in a rural farming community on State Highway 7 in eastern Nacogdoches County. The church was founded during a revival being held in the community of Martinsville and has been in continuous operation ever since. The church grew throughout its lifetime, reaching record attendance and membership numbers between 1950 and 1980. Since the early 2000s, church attendance and membership has been in decline. This thesis outlines the history of Martinsville Baptist Church and explains conservation measures taken during the archival processing and digitization of records in the Martinsville Baptist Church Collection

Interactions between trivalent rare earth oxides and mixed [Hbet][Tf2N]:H2O systems in the development of a one-step process for the separation of light from heavy rare earth elements

The factors, including ionic liquid:water ratios, temperature, solvent:solute contact times, and the effect of dissolved rare earth metal ions on the [Hbet][Tf2N]:H2O thermometric phase change are determined to develop a process for separating the light from the heavy rare earth metal oxides in [Hbet][Tf2N]:H2O mixtures. The relative solubility data for three light (La2O3, Nd2O3, and Eu2O3), two heavy (Y2O3 and Yb2O3) rare earth metal oxides (REOs), and Gd2O3 at different temperatures and different solute:solvent contact times are reported for 1:1 [Hbet][Tf2N]:H2O. The light REOs dissolve easily at 57 °C with the La and Eu reaching maximum solubility within minutes while the heavy REOs have very low solubilities at this temperature with negligible amounts being dissolved for contact times less than 80 min. Gd2O3 dissolves more slowly than the La, Eu, and Nd oxides at 57 °C reaching maximum solubility only after 160 min. Changing the [Hbet][Tf2N]:H2O ratio from 1:1 to 16:1 increases the time required to dissolve the REOs. The times taken to reach maximum solubility decrease for all of the REOs up to 95 °C, resulting in the separations between the light and heavy rare earth elements, and Gd becoming less distinct. The presence of rare earth metal ions in [Hbet][Tf2N]:H2O results in a reduction in the upper critical solution temperature (UCST) of the solvent from 55.6 °C to as low as 31.8 °C with Gd3+. The best separation of light from heavy REOs is achieved at 57 °C but better separation of Gd from the light REOs is achieved at 40 °C, below the solvent UCST. The best conditions for a one-step separation of light from heavy REOs in [Hbet][Tf2N]:H2O mixtures is achieved with 1:1 [Hbet][Tf2N]:H2O at 57 °C using short contact oxide:solvent times (maximum 5 min). Separations of light from heavy REOs, in waste phosphor samples, containing La2O3, CeO2, Eu2O3, Gd2O3, Tb3O4 and Y2O3, are also achieved even in the presence of high concentrations of heavy REOs using short contact times. The use of [Hbet][Tf2N]:H2O as a means of separating light and heavy REOs is aided by the ease of recycling the solvent which can be recycled and reused at least five times with little loss of solvent quality or efficiency

Use of extraction chromatography in the recycling of critical metals from thin film Leach solutions

Phosphors and optoelectronic thin film electronic device layers contain critical metals including lanthanides and indium that should be recycled. Solvent impregnated resins (SIRs) containing (i) DEHPA (ii) DODGAA and (iii) DODGAA with the ionic liquid [C4mim][Tf2N] are investigated in extraction chromatography methodologies to recover and separate critical metals from dilute solutions that model those leached from thin films. Optimum adsorption of metals occurs at pH 1.5-3.5 but is highest on DODGAA-[C4mim][Tf2N]. The recovery and separation of adsorbed metal species on the DODGAA-[C4mim][Tf2N] SIR resin from solutions containing the glass matrix ions, Ca(II) and Al(III), along with In(III) and Sn(IV) or lanthanide ions is achieved by elution with HNO3. Ca(II) and Al(III) are completely eluted with 0.1M HNO3 retaining the target critical metal species on the resin. Separation of In from Sn is achieved by elution of In(III) with 2.5M HNO3 and Sn(IV) with 5M acid. La is separated from the other lanthanides by elution of La(III) with 2.5M HNO3 and the remaining lanthanides with 5M acid. The SIR resins can be reused over a series of at least five cycles of loading, stripping, and rinsing to reduce reagent costs and achieve economic critical metal recovery by extraction chromatography

Nitrogen-vacancy defects in germanium

While nitrogen doping has been investigated extensively in silicon, there is only limited information on its interaction with vacancies in germanium, despite most point defect processes in germanium being vacancy controlled. Thus, spin polarized density functional theory calculations are used to examine the association of nitrogen with lattice vacancies in germanium and for comparison in silicon. The results demonstrate significant charge transfer to nitrogen from nearest neighbour Ge and strong N-Ge bond formation. The presence of vacancies results in a change in nitrogen coordination (from tetrahedral to trigonal planar) though the total charge transfer to N is maintained. A variety of different nitrogen vacancy clusters are considered all of which demonstrated strong binding energies. Substitutional nitrogen remains an effective trap for vacancies even if it has already trapped one vacancy

Symptom Exacerbation and Adherence to Antiretroviral Therapy During the Menstrual Cycle: A Pilot Study

Our objective is to investigate the relationship between drug and menstrual cycle symptoms in HIV+ women receiving antiretroviral therapy (HAART). Interviews were done for 12 weeks with 54 HIV+ women receiving HAART. Patients were asked if they experienced any of 28 symptoms associated with HAART and the menstrual cycle and about HAART adherence. Weeks were divided into menstrual weeks (MWs), premenstrual weeks (PWs), and other weeks. Women reported more bloating (P = .02) and cramps (P = .001) during MWs. Skin problems (P = .08) and breast tenderness (P = .03) were experienced during PWs. Feeling tired/loss of energy (P = .05), joint pain (P = .02), and chills (P = .03) were higher in non-MW/PWs. Women were slightly less adherent during the MWs (89%) than PWs (94%) and other weeks (93%). Feeling sad or depressed (P = .01) was associated with nonadherence. Experiencing certain symptoms associated with both the menstrual cycle and HAART drugs was related with nonadherence

Models and Strategies for Variants of the Job Shop Scheduling Problem

Recently, a variety of constraint programming and Boolean satisfiability approaches to scheduling problems have been introduced. They have in common the use of relatively simple propagation mechanisms and an adaptive way to focus on the most constrained part of the problem. In some cases, these methods compare favorably to more classical constraint programming methods relying on propagation algorithms for global unary or cumulative resource constraints and dedicated search heuristics. In particular, we described an approach that combines restarting, with a generic adaptive heuristic and solution guided branching on a simple model based on a decomposition of disjunctive constraints. In this paper, we introduce an adaptation of this technique for an important subclass of job shop scheduling problems (JSPs), where the objective function involves minimization of earliness/tardiness costs. We further show that our technique can be improved by adding domain specific information for one variant of the JSP (involving time lag constraints). In particular we introduce a dedicated greedy heuristic, and an improved model for the case where the maximal time lag is 0 (also referred to as no-wait JSPs).Comment: Principles and Practice of Constraint Programming - CP 2011, Perugia : Italy (2011

Trace element analyses indicative of paleodiets in Middle Miocene mammals from the Somosaguas site (Madrid, Spain)

Trace element analysis of fossil bone and enamel constitutes a useful tool to characterize the paleoecological behavior of mammals. Up to now, most trace element studies have focused on Plio-Pleistocene fossils. Here, we show that paleodietary inferences based on trace element analyses can be also obtained from ~14Ma old Miocene mammals, in a period of time when important paleoclimatic changes took place due to the development of the East Antarctic ice sheet. Trace element ratio (Ba/Ca, Sr/Ca) analyses have been performed on herbivore tooth enamel (gomphothere Gomphotherium angustidens, equid Anchitherium cf. A. cursor, suid Conohyus simorrensis and ruminants) across three stratigraphic levels from the Somosaguas site (Middle Miocene, Madrid Basin, Spain). Previous scanning electron microscope, rare earth element and stable isotope analyses suggested minimal diagenetic alteration of the tooth enamel samples. Trace element analyses reported here show different paleoecological behavior among the studied fossil taxa. Anchitherium cf. A. cursor shows higher Ba/Ca and Sr/Ca ratios than Gomphotherium angustidens, indicating the equid was a mixed-feeder, while the gomphothere was a browser. The enrichment in Ba/Ca and Sr/Ca ratios in the ruminants is attributed to differences in their gastrointestinal tracts and to a more grazing diet. A high variability in trace element values characterizes the suid Conohyus simorrensis, which is believed to be connected to some degree of omnivory

Test of nuclear level density inputs for Hauser-Feshbach model calculations

The energy spectra of neutrons, protons, and alpha-particles have been measured from the d+59Co and 3He+58Fe reactions leading to the same compound nucleus, 61$Ni. The experimental cross sections have been compared to Hauser-Feshbach model calculations using different input level density models. None of them have been found to agree with experiment. It manifests the serious problem with available level density parameterizations especially those based on neutron resonance spacings and density of discrete levels. New level densities and corresponding Fermi-gas parameters have been obtained for reaction product nuclei such as 60Ni,60Co, and 57Fe