Metabolic Engineering

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Cantua dendritica (Polemoniaceae), a New Species from Peru, and Two New Cantua Names

Cantua dendritica is described as new. This species is apparently restricted to the region around Paucartambo, Department of Cusco, Peru. Related to, and frequently identified as, Cantua flexuosa, this new species differs in its glandular calyx, highly branched trichomes on the margin of the corolla lobes, and its softly herbaceous, glandular pilose leaves. In addition, two new names are proposed in Cantua for the two species of Huthia that have been transferred to Cantua, C. volcanica (formerly Huthia caerulea), and C. mediamnis (formerly H. longiflora)

Window Dressing, Data Mining, Or Data Errors: A Re-Examination Of The Dogs Of The Dow Theory

We re-examine the Dow dividend yield anomaly to ascertain if data errors create the superior returns of the trading rule.  Empirical testing, using both parametric and nonparametric methods, suggests that the trading rule outperforms the index.  Additionally, data errors are not the drivers of superior trading rule returns.  Moreover, the Chow breakpoint test of structural stability suggests that neither window dressing nor data mining explain this phenomenon.  Finally, a turn of the year formation date fails to explain superior trading rule returns, further mitigating the data mining explanation

Rapid in vitro prototyping of O-methyltransferases for pathway applications in Escherichia coli

O-Methyltransferases are ubiquitous enzymes involved in biosynthetic pathways for secondary metabolites such as bacterial antibiotics, human catecholamine neurotransmitters, and plant phenylpropanoids. While thousands of putative O-methyltransferases are found in sequence databases, few examples are functionally characterized. From a pathway engineering perspective, however, it is crucial to know the substrate and product ranges of the respective enzymes to fully exploit their catalytic power. In this study, we developed an in vitro prototyping workflow that allowed us to screen ∼30 enzymes against five substrates in 3 days with high reproducibility. We combined in vitro transcription/translation of the genes of interest with a microliter-scale enzymatic assay in 96-well plates. The substrate conversion was indirectly measured by quantifying the consumption of the S-adenosyl-L-methionine co-factor by time-resolved fluorescence resonance energy transfer rather than time-consuming product analysis by chromatography. This workflow allowed us to rapidly prototype thus far uncharacterized O-methyltransferases for future use as biocatalysts

Development of a sustainable bioprocess for the production of novel Xylooligosaccharides (XOS) and their potential application

The growing demand of novel food products for well-being and age related issues coupled with increasing health care expenditure has attracted global attention on prebiotics. Xylooligosaccarides (XOS) are the only nutraceuticals that can be produced from lignocellulosic biomass. Indeed, XOS can be produced from agricultural crop residues, which is encouraging to the food ingredient industries, as these raw materials are inexpensive, abundant and renewable in nature. XOS beneficial effects include, besides the selective growth stimulation of beneficial gut microflora, enhanced mineral absorption, cholesterol lowering, glucose homeostasis, pathogen exclusion, immune modulation, antioxidant and anticarcinogenic activities, among others. The precursor for XOS is xylan. Xylan is the polysaccharide accounting for 25 to 50% of the dry mass of lignocellulosic-based agriculture residues. XOS can then be produced through chemical or enzymatic processes. The microbial or enzymatic conversion of xylan into value-added useful products, as XOS, holds a great promise for the use of a variety of agro-food and industrial residues. The goal of this PhD project is to develop a sustainable bioprocess by exploring the use of agro-industrial residues for the production of novel XOS and to evaluate their effect on the probiotics viability under simulated gastric conditions. The proposed tasks involve several design and engineering approaches to optimize the production process.info:eu-repo/semantics/publishedVersio

Using graphical and pictorial representations to teach introductory astronomy students about the detection of extrasolar planets via gravitational microlensing

The detection and study of extrasolar planets is an exciting and thriving field in modern astrophysics, and an increasingly popular topic in introductory astronomy courses. One detection method relies on searching for stars whose light has been gravitationally microlensed by an extrasolar planet. In order to facilitate instructors' abilities to bring this interesting mix of general relativity and extrasolar planet detection into the introductory astronomy classroom, we have developed a new Lecture-Tutorial, "Detecting Exoplanets with Gravitational Microlensing." In this paper, we describe how this new Lecture-Tutorial's representations of astrophysical phenomena, which we selected and created based on theoretically motivated considerations of their pedagogical affordances, are used to help introductory astronomy students develop more expert-like reasoning abilities.Comment: 10 pages, 10 figures, accepted for publication in the American Journal of Physic

Predicted rocket and shuttle effects on stratospheric ozone

The major chemical effluents of either solid- or liquid-fueled rockets that can potentially perturb stratospheric ozone include chlorine compounds (HCl), nitrogen compounds (NO(x)), and hydrogen compounds (H2 and H2O). Radicals (Cl, ClO, H, OH, HO2, NO, and NO2) formed directly or indirectly from rocket exhaust can cause the catalytic destruction of ozone. Other exhaust compounds that could presumably lead to ozone destruction either by direct reaction with ozone or by providing a surface for heterogeneous processes include the particulates Al2O3, ice, and soot. These topics are discussed in terms of the possible effects of rocket exhausts on stratospheric ozone

Flight-based chemical characterization of biomass burning aerosols within two prescribed burn smoke plumes

Biomass burning represents a major global source of aerosols impacting direct radiative forcing and cloud properties. Thus, the goal of a number of current studies involves developing a better understanding of how the chemical composition and mixing state of biomass burning aerosols evolve during atmospheric aging processes. During the Ice in Clouds Experiment-Layer Clouds (ICE-L) in the fall of 2007, smoke plumes from two small Wyoming Bureau of Land Management prescribed burns were measured by on-line aerosol instrumentation aboard a C-130 aircraft, providing a detailed chemical characterization of the particles. After ~2–4 min of aging, submicron smoke particles, produced primarily from sagebrush combustion, consisted predominantly of organics by mass, but were comprised primarily of internal mixtures of organic carbon, elemental carbon, potassium chloride, and potassium sulfate. Significantly, the fresh biomass burning particles contained minor mass fractions of nitrate and sulfate, suggesting that hygroscopic material is incorporated very near or at the point of emission. The mass fractions of ammonium, sulfate, and nitrate increased with aging up to ~81–88 min and resulted in acidic particles. Decreasing black carbon mass concentrations occurred due to dilution of the plume. Increases in the fraction of oxygenated organic carbon and the presence of dicarboxylic acids, in particular, were observed with aging. Cloud condensation nuclei measurements suggested all particles >100 nm were active at 0.5% water supersaturation in the smoke plumes, confirming the relatively high hygroscopicity of the freshly emitted particles. For immersion/condensation freezing, ice nuclei measurements at −32 °C suggested activation of ~0.03–0.07% of the particles with diameters greater than 500 nm

The Atmospheric Effects of Stratospheric Aircraft: a First Program Report

Studies have indicated that, with sufficient technology development, high speed civil transport aircraft could be economically competitive with long haul subsonic aircraft. However, uncertainty about atmospheric pollution, along with community noise and sonic boom, continues to be a major concern; and this is addressed in the planned 6 yr HSRP begun in 1990. Building on NASA's research in atmospheric science and emissions reduction, the AESA studies particularly emphasizing stratospheric ozone effects. Because it will not be possible to directly measure the impact of an HSCT aircraft fleet on the atmosphere, the only means of assessment will be prediction. The process of establishing credibility for the predicted effects will likely be complex and involve continued model development and testing against climatological patterns. Lab simulation of heterogeneous chemistry and other effects will continue to be used to improve the current models

Toward a more physical representation of precipitation scavenging in global chemistry models: cloud overlap and ice physics and their impact on tropospheric ozone

Uptake and removal of soluble trace gases and aerosols by precipitation represents a major uncertainty in the processes that control the vertical distribution of atmospheric trace species. Model representations of precipitation scavenging vary greatly in their complexity, and most are divorced from the physics of precipitation formation and transformation. Here, we describe a new large-scale precipitation scavenging algorithm, developed for the UCI chemistry-transport model (UCI-CTM), that represents a step toward a more physical treatment of scavenging through improvements in the formulation of the removal in sub-gridscale cloudy and ambient environments and their overlap within the column as well as ice phase uptake of soluble species. The UCI algorithm doubles the lifetime of HNO<sub>3</sub> in the upper troposphere relative to a scheme with commonly used fractional cloud cover assumptions and ice uptake determined by Henry's Law and provides better agreement with HNO<sub>3</sub> observations. We find that the process of ice phase scavenging of HNO<sub>3</sub> is a critical component of the tropospheric O<sub>3</sub> budget, but that NO<sub>x</sub> and O<sub>3</sub> mixing ratios are relatively insensitive to large differences in the removal rate. Ozone abundances are much more sensitive to the lifetime of HNO<sub>4</sub>, highlighting the need for better understanding of its interactions with ice and for additional observational constraints