(Beta)-Barium borate thin film formation on silicon through metal organic decompostion of two novel precursors, barium dimesitylborinate and barium (18-crown-6) Cyclotriboroxane

Two novel precursors, barium dimesitylborinate and barium (18-crown-6) cyclotriboroxane, were synthesized to produce thin films of p-barium borate (P-Ba3B60i2) via the metal organic decomposition (MOD) process. The two precursor reagents were characterized by nuclear magnetic resonance, infrared spectroscopy, differential thermal analysis (DSC), thermal gravimetric analysis (TGA), and elemental analysis. The MOD process was initially used to produce P-barium borate powders. The powders were heated for 1 hour under oxygen flow at various temperatures. The formation of p-barium borate was confirmed by powder X-ray diffraction of the products of thermolysis of both precursors, p-barium borate formation occurred at 800 C and 550 C for barium dimesitylborinate and barium (crown ether) cyclotriboroxane, respectively. Thin films of both precursor compounds were produced by a spin coating process. The substrates used were silicon wafers with a (100) orientation. Tetrahydrofuran was found to be a good solvent for the barium dimesitylborinate precursor. Ethanol was used for barium (crown ether) cyclotriboroxane. Again, the MOD process was used. The films were heated to various temperatures for various times under flowing oxygen. The films were then analyzed by thin film X-ray diffraction to determine if p-barium borate was formed. Due to substrate interaction thin films produced from the barium dimesitylborinate precursor did not contain P-barium borate. However, monophasic P-barium borate films were produced from heating the barium (crown ether) cyclotriboroxane precursor to temperatures between 600 and 700 C for 1 hour. The six membered anionic borate ring is the key structural unit in p-barium borate. Since the ring unit is already present in the barium (crown ether) cyclotriboroxane precursor lower temperature processing is needed, and substrate interaction becomes less likely. Ellipsometry was used to measure the index of refraction of the films. The index of refraction, measured by ellipsometry, was 1.51 for the film produced from barium dimesitylborinate. The index of refraction was 1.68 for the film produced from barium (crown ether) cyclotriboroxane

Relations of environmental contaminants, algal toxins, and diet with the reproductive success of American alligators on Florida Lakes

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Dual Method Headphone Amplifier

Many high impedance headphones underperform their full potential when directly connected to the audio source. Amplifiers boost the audio signal and provide the headphones with sufficient power to ensure their maximum performance. The invention of transistors caused vacuum tube implementation to decline, leaving many audiophiles unsatisfied with the transistor’s sound signature. Vacuum tubes and transistors both amplify signals, however the distinct “tube sound” has vanished. We have designed and created a product where the user selectively switches between solid-state transistor and tube amplification to compare the sound signatures of each amplification method. The ability to switch between the solid-state and tube amplifiers creates the ability to achieve a more customized sound for individual songs and improve the user’s listening experience. This requires the design of two separate amplifiers and circuitry to switch back and forth between amplification methods without pausing the music or unplugging any device

Can the Results of Biodiversity-Ecosystem Productivity Studies Be Translated to Bioenergy Production?

Biodiversity experiments show that increases in plant diversity can lead to greater biomass production, and some researchers suggest that high diversity plantings should be used for bioenergy production. However, many methods used in past biodiversity experiments are impractical for bioenergy plantings. For example, biodiversity experiments often use intensive management such as hand weeding to maintain low diversity plantings and exclude unplanted species, but this would not be done for bioenergy plantings. Also, biodiversity experiments generally use high seeding densities that would be too expensive for bioenergy plantings. Here we report the effects of biodiversity on biomass production from two studies of more realistic bioenergy crop plantings in southern Michigan, USA. One study involved comparing production between switchgrass (Panicum virgatum) monocultures and species-rich prairie plantings on private farm fields that were managed similarly to bioenergy plantings. The other study was an experiment where switchgrass was planted in monoculture and in combination with increasingly species-rich native prairie mixtures. Overall, we found that bioenergy plantings with higher species richness did not produce more biomass than switchgrass monocultures. The lack of a positive relationship between planted species richness and production in our studies may be due to several factors. Non-planted species (weeds) were not removed from our studies and these non-planted species may have competed with planted species and also prevented realized species richness from equaling planted species richness. Also, we found that low seeding density of individual species limited the biomass production of these individual species. Production in future bioenergy plantings with high species richness may be increased by using a high density of inexpensive seed from switchgrass and other highly productive species, and future efforts to translate the results of biodiversity experiments to bioenergy plantings should consider the role of seeding density

Height and clonality traits determine plant community responses to fertilization

Fertilization via agricultural inputs and nutrient deposition is one of the major threats to global terrestrial plant richness, yet we still do not fully understand the mechanisms by which fertilization decreases plant richness. Tall clonal species have recently been proposed to cause declines in plant species richness by increasing in abundance in response to fertilization and competing strongly with other species. We tested this hypothesis in a fertilization experiment in a low productivity grassland by using a novel experimental manipulation of the presence vs. absence of clonal species and by examining the role of height within these treatments. We found that fertilization decreased species richness more in the presence than absence of clonal species. We also found that only tall species increased in biomass in response to fertilization. In the absence of clonal species, fertilization increased biomass of tall non clonal species. However, in the presence of clonal species, fertilization decreased tall non clonal biomass and only tall clonal biomass increased. Fertilization caused almost all short species to be lost in the presence, but not the absence, of clonal species and caused greater declines in the mean and variance of light levels in the presence of clonal species. These results show that the traits of species in a community can determine the magnitude of species loss due to fertilization. The strongly negative effect of tall clonals on species richness in fertilized plots is likely a result of their capacity to decrease light levels to a greater extent and more uniformly than non clonal species, and thereby drive the exclusion of short species. These results help clarify the mechanisms whereby fertilization decreases grassland plant species richness and suggest that efforts to prevent the loss of species under fertilized conditions may be most effective when they focus on controlling the biomass of tall clonal species

Low-Overhead Run-Time Memory Leak Detection and Recovery

Memory leaks are known to be a major cause of reliability and performance issues in software. This paper describes a run-time scheme that detects and removes memory leaks with minimal performance overhead and with no modifications to application source code. The scheme consists of a first stage where a pattern recognition technique proactively detects subtle memory leaks, followed by a more resource-intensive second stage that scans the memory space of an application and removes detected memory leaks. The pattern recognition technique in the first stage is based on the multivariate state estimation technique (MSET) which provides accurate detection of subtle memory leaks with very little overhead. The second stage is only activated when problems are identified by the first stage. For our prototype, this second stage is based on debugging and analysis tools provided by Solaris 10. Due to the low-overhead impact of the first stage, the system can be monitored for memory leaks without incurring noticeable performance degradation. We present and discuss some results from our unique proactive detection and debugging methodology.

Nkx2.2 is expressed in a subset of enteroendocrine cells with expanded lineage potential

There are two major stem cell populations in the intestinal crypt region that express either Bmi1 or Lgr5; however, it has been shown that other populations in the crypt can regain stemness. In this study, we demonstrate that the transcription factor NK2 homeobox 2 (Nkx2.2) is expressed in enteroendocrine cells located in the villus and crypt of the intestinal epithelium and is coexpressed with the stem cell markers Bmi1 and Lgr5 in a subset of crypt cells. To determine whether Nkx2.2-expressing enteroendocrine cells display cellular plasticity and stem cell potential, we performed genetic lineage tracing of the Nkx2.2-expressing population using Nkx2.2Cre/;R26RTomato mice. These studies demonstrated that Nkx2.2+ cells are able to give rise to all intestinal epithelial cell types in basal conditions. The proliferative capacity of Nkx2.2-expressing cells was also demonstrated in vitro using crypt organoid cultures. Injuring the intestine with irradiation, systemic inflammation, and colitis did not enhance the lineage potential of Nkx2.2-expressing cells. These findings demonstrate that a rare mature enteroendocrine cell subpopulation that is demarcated by Nkx2.2 expression display stem cell properties during normal intestinal epithelial homeostasis, but is not easily activated upon injury

A Molecular Code for Identity in the Vomeronasal System

SummaryIn social interactions among mammals, individuals are recognized by olfactory cues, but identifying the key signals among thousands of compounds remains a major challenge. To address this need, we developed a new technique, component-activity matching (CAM), to select candidate ligands that “explain” patterns of bioactivity across diverse complex mixtures. Using mouse urine from eight different sexes and strains, we identified 23 components to explain firing rates in seven of eight functional classes of vomeronasal sensory neurons. Focusing on a class of neurons selective for females, we identified a novel family of vomeronasal ligands, steroid carboxylic acids. These ligands accounted for much of the neuronal activity of urine from some female strains, were necessary for normal levels of male investigatory behavior of female scents, and were sufficient to trigger mounting behavior. CAM represents the first step toward an exhaustive characterization of the molecular cues for natural behavior in a mammalian olfactory system