40,383 research outputs found
Geobacter sulfurreducens inner membrane cytochrome transcriptional and phenotypic data
No full textThe data files include raw data as well as analyzed results for transcriptional analysis of WT G. sulfurreducens and mutant lacking BccR (GSU0598) under fumarate vs iron citrate growth conditions. This dataset also includes the phenotypic data files for experiments associated with this project.Geobacter sulfurreducens utilizes extracellular electron acceptors such as Mn(IV), Fe(III), syntrophic partners, and electrodes that vary from +0.4 to −0.3 V vs. Standard Hydrogen Electrode (SHE), representing a potential energy span that should require a highly branched electron transfer chain. Here we describe CbcBA, a bc-type cytochrome essential near the thermodynamic limit of respiration when acetate is the electron donor. Mutants lacking cbcBA ceased Fe(III) reduction at −0.21 V vs. SHE, could not transfer electrons to electrodes between −0.21 and −0.28 V, and could not reduce the final 10% – 35% of Fe(III) minerals. As redox potential decreased during Fe(III) reduction, cbcBA was induced with the aid of the regulator BccR to become one of the most highly expressed genes in G. sulfurreducens. Growth yield (CFU/mM Fe(II)) was 112% of WT in ∆cbcBA, and deletion of cbcL (an unrelated bc-cytochrome essential near −0.15 V) in ΔcbcBA increased yield to 220%. Together with ImcH, which is required at high redox potentials, CbcBA represents a third cytoplasmic membrane oxidoreductase in G. sulfurreducens. This expanding list shows how metal-reducing bacteria may constantly sense redox potential to adjust growth efficiency in changing environments.Office of Naval Research: N00014-16-1-2194, and N00014-18-1-2632.Joshi, Komal; Chan, Chi Ho; Bond, Daniel R. (2021). Geobacter sulfurreducens inner membrane cytochrome transcriptional and phenotypic data. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/5AMD-ZW33
An empirical comparison of convertible bond valuation models
No full textThis paper empirically compares three convertible bond valuation models. We use an innovative approach where all model parameters are estimated by the Marquardt algorithm using a subsample of convertible bond prices. The model parameters are then used for out-of-sample forecasts of convertible bond prices. The mean absolute deviation is 1.86% for the Ayache-Forsyth-Vetzal model, 1.94% for the Tsiveriotis-Fernandes model, and 3.73% for the Brennan-Schwartz model. For this and other measures of fit, the Ayache-Forsyth-Vetzal and Tsiveriotis-Fernandes models outperform the Brennan-Schwartz model
FINANCING COMMUNITY FACILITIES: A CASE STUDY OF THE PARKS AND RECREATIONAL GENERAL OBLIGATION BOND MEASURE OF SAN JOSE, CALIFORNIA
No full textThis study of the City of San Jose’s Parks and Recreation General Obligation (GO) Bond Measure seeks to identify the politics-, management-, and planning-related lessons learned by the City as it developed its community facilities using the GO bonds proceeds. The study finds that these lessons include: be conservative in what you promise the residents; be prepared for changes in economic environment by identifying supplementary funding sources should the primary source not yield adequate funds; make sure that the jurisdiction is organizationally capable of handling the increased workload; and prepare detailed project plans prior to the bond issuance.Community Infrastructure and Services; Municipal Bonds; Public Finance
Theoretical approaches to estimating homolytic bond dissociation energies of organocopper and organosilver compounds
No full textAlthough organocopper and organosilver compounds are known to decompose by homolytic pathways among others, surprisingly little is known about their bond dissociation energies (BDEs). In order to address this deficiency, the performance of the DFT functionals BLYP, B3LYP, BP86, TPSSTPSS, BHandHLYP, M06L, M06, M06-2X, B97D, and PBEPBE, along with the double hybrids, mPW2-PLYP, B2-PLYP, and the ab initio methods, MP2 and CCSD(T), have been benchmarked against the thermochemistry for the M–C homolytic BDEs (<i>D</i><sub>0</sub>) of Cu–CH<sub>3</sub> and Ag–CH<sub>3</sub>, derived from guided ion beam experiments and CBS limit calculations (<i>D</i><sub>0</sub>(Cu–CH<sub>3</sub>) = 223 kJ·mol<sup>–1</sup>; <i>D</i><sub>0</sub>(Ag–CH<sub>3</sub>) = 169 kJ·mol<sup>–1</sup>). Of the tested methods, in terms of chemical accuracy, error margin, and computational expense, M06 and BLYP were found to perform best for homolytic dissociation of methylcopper and methylsilver, compared with the CBS limit gold standard. Thus the M06 functional was used to evaluate the M–C homolytic bond dissociation energies of Cu–R and Ag–R, R = Et, Pr, <i>i</i>Pr, <i>t</i>Bu, allyl, CH<sub>2</sub>Ph, and Ph. It was found that <i>D</i><sub>0</sub>(Ag–R) was always lower (∼50 kJ·mol<sup>–1</sup>) than that of <i>D</i><sub>0</sub>(Cu–R). The trends in BDE when changing the R ligand reflected the H–R bond energy trends for the alkyl ligands, while for R = allyl, CH<sub>2</sub>Ph, and Ph, some differences in bond energy trends arose. These trends in homolytic bond dissociation energy help rationalize the previously reported (Rijs, N. J.; O’Hair, R. A. J. <i>Organometallics</i><b>2010</b>, <i>29</i>, 2282–2291) fragmentation pathways of the organometallate anions, [CH<sub>3</sub>MR]<sup>−</sup>
James Bond: international man of gastronomy
No full textThis article is concerned with the representation of food and drink in Ian Fleming’s James Bond novels. In particular, it examines how the author uses Bond’s culinary knowledge and habits of consumption as an important constituent of his hero’s character. Similarly, the food choices of other characters, notably villains, are shown to be linked, by Fleming, to core aspects of their identity − principally their ethnicity. Bond’s impulse to observe and classify, very much in evidence in the novels’ food sequences, is examined in terms of the texts’ construction of Bond as a skilled identifier of signs
Sensitivity bond graphs
No full textA sensitivity bond graph, of the same structure as the system bond graph, is shown to provide a simple and effective method of generating sensitivity functions of use in optimisation. The approach is illustrated in the context of partially known system parameter and state estimation
Understanding intermolecular C–F bond activation by a transient titanium neopentylidyne: experimental and theoretical studies on the competition between 1,2-CF bond addition and [2 + 2]-cycloadditionβ-fluoride elimination
No full textComplex (PNP)Ti=(CHBu)-Bu-t((CH2Bu)-Bu-t) (PNP- = N[2-P(CHMe2)(2)-4-methylphenyl](2)) eliminates (H3CBu)-Bu-t to form transient (PNP)Ti (CBu)-Bu-t, which activates the C-F bond of ortho-difluoropyridine and ortho-fluoropyridine to form the alkylidene-fluoride complexes, (PNP)Ti=C[Bu-t(NC5H3F)](F) (1) and (PNP)Ti=C[Bu-t(NC5H4)](F) (2), respectively. When (PNP)Ti=(CHBu)-Bu-t((CH2Bu)-Bu-t) is treated with meta-fluoropyridine, the ring-opened product (PNP)Ti(C(Bu-t)CC4H3-3-FNH) (3) is the only recognizable titanium metal complex formed. Theoretical studies reveal that pyridine binding disfavors 1,2-CF bond addition across the alkylidyne ligand in the case of ortho-fluoride pyridines, while sequential [2 + 2]-cycloaddition/beta-fluoride elimination is a lower energy pathway. In the case of meta-fluoropyridine, [2 + 2]-cycloaddition and subsequent ring-opening metathesis is favored as opposed to C-H bond addition or sequential [2 + 2]-cycloaddition/beta-hydride elimination. In all cases, C-H bond addition of ortho-fluoropyridines or meta-fluoropyridine is discouraged because such substrate must bind to titanium via its C-H bond, which is rather weak compared to the titanium-pyridine binding
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