Electrochemical Studies of Organic and Organometallic Compounds in the Pursuit of Electrocatalytic Carbon Dioxide Reduction

Carbon dioxide is the main contributor to the greenhouse effect in the world today; developing renewable energy sources and addressing anthropogenic CO2 release into the atmosphere are two key ways of addressing its increasing impact. Electrocatalytic reduction to products like methanol or carbon monoxide is one useful path to address the rapid increase of carbon dioxide, and the fac-M(bpy-R)(CO)3X family of complexes (M = Mn or Re; bpy-R = substituted 2,2’-bipyridine; X = Cl, Br, etc.) is one class of effective CO2 reduction catalysts. Although the capability of the rhenium complex Re(PyBimH)(CO)3Cl (PyBimH = 2-(2-pyridyl)benzimidazole) as a CO2 reduction catalyst was previously determined to be minimal, the underlying reasons why were not explained, which is odd when considering that protic sites on the ligand have been shown to increase CO2 reactivity. In this work, we show that the lack of electrocatalytic activity is due to a hydrogen atom transfer reaction that takes place upon reduction. In the process of testing for catalytic activity, a rapid method of determining the effective pKa of acidic species in acetonitrile using cyclic voltammetry was discovered and explored. The pKa of the rhenium complex was estimated through the cyclic voltammetry method to be , in reasonable agreement with DFT calculations. Because determining acidity in non-aqueous solvents is not trivial using established methods, the discovery of a method to accurately estimate the pKa of a species containing an acidic X-H bond is valuable. In addition to the organometallic rhenium complex, organic species buckminsterfullerene (C60) and benzil were explored as viable catalysts for the electrochemical reduction of carbon dioxide. Buckminsterfullerene showed minor electrochemical activity in the presence of carbon dioxide as observed by cyclic voltammetry and infrared spectroelectrochemistry. In this study, cyclic voltammetry and infrared spectroelectrochemistry showed that benzil reduces carbon dioxide at a lower overpotential than C60 and most other electrocatalysts. The production of oxalate from carbon dioxide by action of monoreduced benzil radical has been proposed, in agreement with literature. In the presence of pyridine, reactivity initially showed increased activity but did not show a linear trend in a quantified study of pyridine concentration

Evaluation of the Social Impact of Reservoir Construction on the Residential Plans of Displaced Persons in Kentucky and Ohio

The states of Kentucky and Ohio have numerous reservoir projects at various stages of planning and construction. Each of the projects produces substantial social impact for the residents of the area and particularly for those persons affected by a loss of property and homes. This impact is not uniform in that people respond differently to displacement and the methods of adjusting relocation are known to differ among people. This research was initiated to develop and test a model for explaining migration under such conditions. The model includes a consideration of people\u27s potential for transferring existing statuses to new residences, the extent to which peoples interests are served by the reservoir, people\u27s knowledge of the reservoir, the social class levels of those displaced and the extent to which people identify with their places of residence. These factors are viewed as affecting people\u27s levels of apprehension and consequently their willingness to separate from their current membership systems. Data for this investigations come from all the adult residents of the areas to be flooded neat Taylorsville, Kentucky and Lebanon, Ohio. These areas are in the Louisville District of the U.S. Army Corps of Engineers and exhibit similar topographies with rural populations of similar socio-economic and social isolation. The testing of this model indicated that apprehensions over money is greatest for those persons who identify strongly with their present homes. Also, apprehension over migration was less for those persons whose vested interests were served by the project. Knowledge of the reservoir project did not reduce apprehensions over moving as was predicted by the model

Factors Affecting Relocation in Response to Reservoir Development

The focus of this paper is on the question of how rural people anticipate forced moves as a result of flood control projects and how they change their life in accepting separation from familiar surroundings. A model of faced migration is presented which sees the variables of socioeconomic status, knowledge of reservoir projects, vested interests and the degree of identification with place of affected persons as producing differential apprehension over moving. Differential apprehension is then seen as producing different attitudes toward the project which will influence the type of migration plans. To test this model of forced migration, data were obtained by means of personal interview with 261 adults located in two areas about to be flooded by multipurpose reservoirs. Goodman and Kruskal \u27s gamma was used as the measure of association for the ordinal data. Basic to the model were the two findings that (1) apprehension over moving relates inversely with people\u27s willingness to separate themselves from their current friends and homes, and (2) that people with favorable attitudes toward flood control projects were less apprehensive over moving and as a consequence were more willing to engage in moves that require greater degrees of separation from their current friends and types of residences. Other findings suggest that those persons whose vested interests would be enhanced by the reservoir project can be expected to engage in moves requiring the greatest amounts of social separation. Knowledge of the reservoir project and its purposes did little to meliorate people\u27s attitudes toward the reservoir project or to facilitate ease of moving. A new variable identification with place, developed for this study, was found to relate strongly with apprehension over moving

Improvement of cryo-EM maps by density modification.

A density-modification procedure for improving maps from single-particle electron cryogenic microscopy (cryo-EM) is presented. The theoretical basis of the method is identical to that of maximum-likelihood density modification, previously used to improve maps from macromolecular X-ray crystallography. Key differences from applications in crystallography are that the errors in Fourier coefficients are largely in the phases in crystallography but in both phases and amplitudes in cryo-EM, and that half-maps with independent errors are available in cryo-EM. These differences lead to a distinct approach for combination of information from starting maps with information obtained in the density-modification process. The density-modification procedure was applied to a set of 104 datasets and improved map-model correlation and increased the visibility of details in many of the maps. The procedure requires two unmasked half-maps and a sequence file or other source of information on the volume of the macromolecule that has been imaged

An Expanded Conformation of Single-Ring GroEL-GroES Complex Encapsulates an 86 kDa Substrate

SummaryElectron cryomicroscopy reveals an unprecedented conformation of the single-ring mutant of GroEL (SR398) bound to GroES in the presence of Mg-ATP. This conformation exhibits a considerable expansion of the folding cavity, with ∼80% more volume than the X-ray structure of the equivalent cis cavity in the GroEL-GroES-(ADP)7 complex. This expanded conformation can encapsulate an 86 kDa heterodimeric (αβ) assembly intermediate of mitochondrial branched-chain α-ketoacid dehydrogenase, the largest substrate ever observed to be cis encapsulated. The SR398-GroES-Mg-ATP complex is found to exist as a mixture of standard and expanded conformations, regardless of the absence or presence of the substrate. However, the presence of even a small substrate causes a pronounced bias toward the expanded conformation. Encapsulation of the large assembly intermediate is supported by a series of electron cryomicroscopy studies as well as the protection of both α and β subunits of the substrate from tryptic digestion

O estresse no manejo pré-abate e na qualidade da carne suína.

O estresse no manejo pré-abate e na qualidade da carne suína; Caracterização do estresse; Avaliação da resposta fisiológica dio estresse; Formas de avaliações; Determinação do cortisol; Determinação de lactato; Mecanismos através dos quais podem afetar a qualidade da carne; Influência da genética na qualidade da carne; Gene rendimento napole (RN); gene Halotano; Situações de estresse no manejo pré-abate.bitstream/item/58222/1/publicacao-i7n63h7v1.pd

Combining chitosan-fish oil-green tea extract as a potential active coating for fresh Atlantic bonito fillet preservation

Sustainable bio-based packaging materials are gaining increasing attention by food manufacturers and consumers, as possible substitutes for synthetic plastic materials. In particular, edible biopolymer coatings/films could be applied to highly perishable food products to preserve their freshness and increase shelf life. Atlantic bonito (Sarda sarda) is a well-known fish from Atlantic Ocean with pleasant taste and high nutritional value. However, it is susceptible to lipid oxidation and spoilage. Therefore, a sustainable and active coating formulation composed by chitosan (CH)-fish oil (FO)-green tea extract (GTE) was developed to be apply on Atlantic bonito fillets surface to extend its shelf life. CH, FO and GTE were selected due to their well-known antioxidant and antimicrobial effects. A Central Composite Rotational Design was developed to evaluate the effect of coating/film compounds concentration CH (0.5-2.31%, w/w), FO (0.20-0.44%, w/w) and GTE (2%, w/w) on their physicochemical and functional properties (e.g., mechanical, barrier, surface properties). The changes in quality of fish fillets were also assessed, such as pH and textural analysis. Based on surface contact angle results, 1.25% CH-0.30% FO-2% GTE formulation (78) was the most promising one due to good coating adhesion ability on fish fillets surface. Also, this formulation showed to be a good barrier to water vapor (2.29 × 10-6 g/(m.s.Pa)) as well as good mechanical properties comparing to other tested formulations. The developed CH-FO-GET coating/film displays properties that allow its use as an environmentally friendly active food packaging system to be applied to Atlantic bonito fillets.info:eu-repo/semantics/publishedVersio

Structure of the SecY channel during initiation of protein translocation

Many secretory proteins are targeted by signal sequences to a protein-conducting channel, formed by prokaryotic SecY- or eukaryotic Sec61-complexes, and are translocated across the membrane during their synthesis1,2. Crystal structures of the inactive channel show that the SecY subunit of the heterotrimeric complex consists of two halves that form an hourglass-shaped pore with a constriction in the middle of the membrane and a lateral gate that faces the lipid phase3-5. The closed channel has an empty cytoplasmic funnel and an extracellular funnel that is filled with a small helical domain, called the plug. During initiation of translocation, a ribosome–nascent chain complex binds to the SecY/Sec61 complex, resulting in insertion of the nascent chain. However, the mechanism of channel opening during translocation is unclear. Here, we have addressed this question by determining structures of inactive and active ribosome–channel complexes with cryo-electron microscopy. Non-translating ribosome–SecY channel complexes derived from Methanococcus jannaschii or Escherichia coli show the channel in its closed state, and indicate that ribosome binding per se causes only minor changes. The structure of an active E. coli ribosome–channel complex demonstrates that the nascent chain opens the channel, causing mostly rigid body movements of the N- and C-terminal halves of SecY. In this early translocation intermediate, the polypeptide inserts as a loop into the SecY channel with the hydrophobic signal sequence intercalated into the open lateral gate. The nascent chain also forms a loop on the cytoplasmic surface of SecY rather than directly entering the channel

MRC2014: Extensions to the MRC format header for electron cryo-microscopy and tomography

Open Access funded by Medical Research CouncilThe MRC binary file format is widely used in the three-dimensional electron microscopy field for storing image and volume data. Files contain a header which describes the kind of data held, together with other important metadata. In response to advances in electron microscopy techniques, a number of variants to the file format have emerged which contain useful additional data, but which limit interoperability between different software packages. Following extensive discussions, the authors, who represent leading software packages in the field, propose a set of extensions to the MRC format standard designed to accommodate these variants, while restoring interoperability. The MRC format is equivalent to the map format used in the CCP4 suite for macromolecular crystallography, and the proposal also maintains interoperability with crystallography software. This Technical Note describes the proposed extensions, and serves as a reference for the standard.We thank Chris Booth and Steffen Meyer from Gatan Inc. for clarifying the format definition used by Digital Micrograph. Acknowledgement for support from National Institute of Health, USA includes: NIGMS grant P41GM103310 (AC and SD), NIBIB grant 5R01-EB005027 (DM), and R01GM080139 (SJL). RH and MW would like to thank the UK Medical Research Council for the award of Partnership Grant MR/J000825/1 to support the establishment of CCP-EM. RH and JS are also supported by MRC grant U105184322