Our Capacity to Do Work: the Future of Energy

Overwhelming evidence of anthropogenic climate change has surfaced in recent years, and energy consumption is primarily to blame. According to the U.S. Energy Infmmation Administration, the United States alone consumed 97.5 quadrillion British the1mal units (Btu) of energy in 2013. We consume so much energy and rely heavily on it in our daily lives, yet as a society we understand so little about it. In a 2009 study sampling 1 001 American adults, the majority expressed concern over energy prices and dependence on foreign oil, yet 40% of those sampled could not identify a fossil fuel, and an even higher percentage could not name a renewable energy technology. The purpose of this thesis is to address society\u27s energy illiteracy in order to create an educated public that can act effectively to correct current energy issues. This thesis outlines the science behind five different energy technologies to show how energy is derived from each technology. The five energy sources addressed are petroleum, biofuels, hydrogen gas, wind energy, and solar energy. Included in the biofuels and hydrogen gas sections are individual research projects conducted at the National Renewable Energy Laboratory and the University ofNebraska-Lincoln, respectively. By focusing on the five aforementioned energy sources, this thesis should provide a brief glimpse at the future of energy

Metabolic engineering of \u3ci\u3eEscherichia coli\u3c/i\u3e for the \u3ci\u3ede novo\u3c/i\u3e stereospecific biosynthesis of 1,2-propanediol through lactic acid

1,2-propanediol (1,2-PDO) is an industrial chemical with a broad range of applications, such as the production of alkyd and unsaturated polyester resins. It is currently produced as a racemic mixture from nonrenewable petroleum-based feedstocks. We have reported a novel artificial pathway for the biosynthesis of 1,2-PDO via lactic acid isomers as the intermediates. The pathway circumvents the cytotoxicity issue caused by methylglyoxal intermediate in the naturally existing pathway. Successful E. coli bioconversion of lactic acid to 1,2-PDO was shown in previous report. Here, we demonstrated the engineering of E. coli host strains for the de novo biosynthesis of 1,2-PDO through this pathway. Under fermenter-controlled conditions, the R-1,2-PDO was produced at 17.3 g/L with a molar yield of 42.2% from glucose, while the S-isomer was produced at 9.3 g/L with a molar yield of 23.2%. The optical purities of the two isomers were 97.5% ee (R) and 99.3% ee (S), respectively. To the best of our knowledge, these are the highest titers of 1,2-PDO biosynthesized by either natural producer or engineered microbial strains that are published in peer-reviewed journals

Possible way out of the Hawking paradox: Erasing the information at the horizon

We show that small deviations from spherical symmetry, described by means of exact solutions to Einstein equations, provide a mechanism to "bleach" the information about the collapsing body as it falls through the aparent horizon, thereby resolving the information loss paradox. The resulting picture and its implication related to the Landauer's principle in the presence of a gravitational field, is discussed.Comment: 11 pages, Latex. Some comments added to answer to some raised questions. Typos corected. Final version, to appear in Int. J. Modern. Phys.

A reinterpretation of the Taub singularity

We reinterpret the well known Taub-singularity in terms of a cylinder symmetric geometry. It is shown that a cylindrical analog to the Einstein-Rosen bridge as well as a cosmic string will be present in the geometry.Comment: 11, Oslo-TP-9-94, TP-MUBR 94-06/

Formulação, desenvolvimento e produção de eletrodos revestidos para soldagem de aços cromo-molibdênio

Esse trabalho está incluído numa linha de pesquisa do Laboratório de Soldagem & Técnicas Conexas (LS&TC), a qual investiga a influência dos compostos do revestimento e elementos de liga sobre as propriedades mecânicas e metalúrgicas do metal de solda. Portanto, se projetou, desenvolveu e produziu integralemente no LS&TC um eletrodo revestido básico de baixo hidrogênio (similar aos AWS E9016-B3), com índice de basicidade de 3,7, para soldagem de aços cromo-molibdênio, o qual foi posteriormente modificado através de adição dos elementos de liga titânio, boro e nióbio. Esses consumíveis (4 tipos) mostraram boas condições operacionais, sendo que as propriedades mecânicas e metalúrgicas dos metais de solda assim produzidos foram investigadas, principalmente a tenacidade, nas condições como soldado e após tratamento térmico, com as mesmas apresentando altos valores, sendo superiores ao mínimo exigido pela norma AWS A5.5-81. O tratamento térmico realizado somente agiu positivamente naqueles metais de solda que não continham nióbio. Por outro lado, a adição dos elementos de liga ao consumível original -principalmente o nióbio - reduziu a tenacidade do metal de solda.This work is part of a research line in progress at the Welding & Related Techniques Laboratory (W&RTL), which investigate the coating compouds and alloy elements influence on weld metal mechanical and metallurgical properties. Therfore, it was fully designed, developed and produced at the W&RTL a low hydrogen basie coaled electrode (similar to AWS E9016-B3), with basicity index 3,7, aiming the welding of chromium-molibdenium steels, which was later on modified through additions of the alloy elements titanium, boron and niobium. These consumables have show fair operational facilities and the mechanical properties of the so produced weld metals were investigated, mainly the toughness in the as welded and after heat treatement conditions, with the results being higher than the minimum imposed by AWS A5.5-81. The heat treatement had a positive effect only on those weld metals without niobium. On the other hand, the alloy elements additions into the original consumable - mainly niobium - produced an overall reduction on weld metal toughness

Reduced Hamiltonian for next-to-leading order Spin-Squared Dynamics of General Compact Binaries

Within the post Newtonian framework the fully reduced Hamiltonian (i.e., with eliminated spin supplementary condition) for the next-to-leading order spin-squared dynamics of general compact binaries is presented. The Hamiltonian is applicable to the spin dynamics of all kinds of binaries with self-gravitating components like black holes and/or neutron stars taking into account spin-induced quadrupolar deformation effects in second post-Newtonian order perturbation theory of Einstein's field equations. The corresponding equations of motion for spin, position and momentum variables are given in terms of canonical Poisson brackets. Comparison with a nonreduced potential calculated within the Effective Field Theory approach is made.Comment: 11 pages, minor changes to match published version at CQ

Contribution of Pentose Catabolism to Molecular Hydrogen Formation by Targeted Disruption of Arabinose Isomerase (\u3ci\u3earaA\u3c/i\u3e) in the Hyperthermophilic Bacterium \u3ci\u3eThermotoga maritima\u3c/i\u3e

Thermotoga maritima ferments a broad range of sugars to form acetate, carbon dioxide, traces of lactate, and near theoretic yields of molecular hydrogen (H2). In this organism, the catabolism of pentose sugars such as arabinose depends on the interaction of the pentose phosphate pathway with the Embden-Myerhoff and Entner-Doudoroff pathways. Although the values for H2 yield have been determined using pentose-supplemented complex medium and predicted by metabolic pathway reconstruction, the actual effect of pathway elimination on hydrogen production has not been reported due to the lack of a genetic method for the creation of targeted mutations. Here, a spontaneous and genetically stable pyrE deletion mutant was isolated and used as a recipient to refine transformation methods for its repair by homologous recombination. To verify the occurrence of recombination and to assess the frequency of crossover events flanking the deleted region, a synthetic pyrE allele, encoding synonymous nucleotide substitutions, was used. Targeted inactivation of araA (encoding arabinose isomerase) in the pyrE mutant was accomplished using a divergent, codon-optimized Thermosipho africanus pyrE allele fused to the T. maritima groES promoter as a genetic marker. Mutants lacking araA were unable to catabolize arabinose in a defined medium. The araA mutation was then repaired using targeted recombination. Levels of synthesis of H2 using arabinose-supplemented complex medium by wild-type and araA mutant cell lines were compared. The difference between strains provided a direct measurement of H2 production that was dependent on arabinose consumption. Development of a targeted recombination system for genetic manipulation of T. maritima provides a new strategy to explore H2 formation and life at an extremely high temperature in the bacterial domain

Deciphering molecular details in the assembly of alpha-type carboxysome

Bacterial microcompartments (BMCs) are promising natural protein structures for applications that require the segregation of certain metabolic functions or molecular species in a defined microenvironment. To understand how endogenous cargos are packaged inside the protein shell is key for using BMCs as nano-scale reactors or delivery vesicles. In this report, we studied the encapsulation of RuBisCO into the α-type carboxysome from Halothiobacillus neapolitan. Our experimental data revealed that the CsoS2 scaffold proteins engage RuBisCO enzyme through an interaction with the small subunit (CbbS). In addition, the N domain of the large subunit (CbbL) of RuBisCO interacts with all shell proteins that can form the hexamers. The binding affinity between the N domain of CbbL and one of the major shell proteins, CsoS1C, is within the submicromolar range. The absence of the N domain also prevented the encapsulation of the rest of the RuBisCO subunits. Our findings complete the picture of how RuBisCOs are encapsulated into the α-type carboxysome and provide insights for future studies and engineering of carboxysome as a protein shell

Vacuum Solutions of Einstein's Equations in Parabolic Coordinates

We present a simple method to obtain vacuum solutions of Einstein's equations in parabolic coordinates starting from ones with cylindrical symmetries. Furthermore, a generalization of the method to a more general situation is given together with a discussion of the possible relations between our method and the Belinsky-Zakharov soliton-generating solutions.Comment: 15 pages, version published in Class. Quantum Gra