There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Multiwfn is a multifunctional program for wavefunction analysis. Its main functions are: (1) Calculating and visualizing real space function, such as electrostatic potential and electron localization function at point, in a line, in a plane or in a spatial scope. (2) Population analysis. (3) Bond order analysis. (4) Orbital composition analysis. (5) Plot density-of-states and spectrum. (6) Topology analysis for electron density. Some other useful utilities involved in quantum chemistry studies are also provided. The built-in graph module enables the results of wavefunction analysis to be plotted directly or exported to high-quality graphic file. The program interface is very user-friendly and suitable for both research and teaching purpose. The code of Multiwfn is substantially optimized and parallelized. Its efficiency is demonstrated to be significantly higher than related programs with the same functions. Five practical examples involving a wide variety of systems and analysis methods are given to illustrate the usefulness of Multiwfn. The program is free of charge and open-source. Its precompiled file and source codes are available from http://multiwfn.codeplex.com.

Multiwfn: a multifunctional wavefunction analyzer.

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

/pdf/climate-change-2007-the-physical-science-basis-1x93ttz9jt.pdf

Climate Change 2007: The Physical Science Basis.

Denitrification is a distinct means of energy conservation, making use of N oxides as terminal electron acceptors for cellular bioenergetics under anaerobic, microaerophilic, and occasionally aerobic conditions. The process is an essential branch of the global N cycle, reversing dinitrogen fixation, and is associated with chemolithotrophic, phototrophic, diazotrophic, or organotrophic metabolism but generally not with obligately anaerobic life. Discovered more than a century ago and believed to be exclusively a bacterial trait, denitrification has now been found in halophilic and hyperthermophilic archaea and in the mitochondria of fungi, raising evolutionarily intriguing vistas. Important advances in the biochemical characterization of denitrification and the underlying genetics have been achieved with Pseudomonas stutzeri, Pseudomonas aeruginosa, Paracoccus denitrificans, Ralstonia eutropha, and Rhodobacter sphaeroides. Pseudomonads represent one of the largest assemblies of the denitrifying bacteria within a single genus, favoring their use as model organisms. Around 50 genes are required within a single bacterium to encode the core structures of the denitrification apparatus. Much of the denitrification process of gram-negative bacteria has been found confined to the periplasm, whereas the topology and enzymology of the gram-positive bacteria are less well established. The activation and enzymatic transformation of N oxides is based on the redox chemistry of Fe, Cu, and Mo. Biochemical breakthroughs have included the X-ray structures of the two types of respiratory nitrite reductases and the isolation of the novel enzymes nitric oxide reductase and nitrous oxide reductase, as well as their structural characterization by indirect spectroscopic means. This revealed unexpected relationships among denitrification enzymes and respiratory oxygen reductases. Denitrification is intimately related to fundamental cellular processes that include primary and secondary transport, protein translocation, cytochrome c biogenesis, anaerobic gene regulation, metalloprotein assembly, and the biosynthesis of the cofactors molybdopterin and heme D1. An important class of regulators for the anaerobic expression of the denitrification apparatus are transcription factors of the greater FNR family. Nitrate and nitric oxide, in addition to being respiratory substrates, have been identified as signaling molecules for the induction of distinct N oxide-metabolizing enzymes.

/pdf/cell-biology-and-molecular-basis-of-denitrification-red4l5iffz.pdf

Cell biology and molecular basis of denitrification.

http://run.unl.pt/bitstream/10362/1662/1/Inorganica%20Chimica%20Acta%20356.pdf

Spectroscopic characterization of a novel 2/(4Fe/4S) ferredoxin isolated from Desulfovibrio desulfuricans ATCC 27774

Iron-sulphur clusters (and other metal-sulphur systems)Desulfovibrio desulfuricans (ATCC 27774) (NIFE) hydrogenase - active sites and reactivity

Introducao: As proteinas sao moleculas orgânicas compostas de aminoacidos e possuem um papel essencial no funcionamento do organismo, pois cabe a ela o fornecimento de todo o material necessario para que o nosso corpo possa se manter e tambem para que nossos orgaos e tecidos consigam se reconstituir. As proteinas auxiliam no crescimento e na reparacao de tecidos, ajudam na producao de enzimas, hormonios, neurotransmissores e anticorpos, na reposicao do gasto energetico das celulas e no transporte de substâncias para o corpo. Objetivo: Compreender os mecanismos da digestao e absorcao de proteinas. Metodologia: Procedeu-se a pesquisa em bases cientificas no Google Academico, SciELO e Periodicos Capes. Resultados: A digestao de proteinas nao ocorre na boca, mas ao longo do percurso passando pelo sitio principal de digestao das proteinas - estomago, atraves da enzima Pepsina, nas celulas acinares pancreaticas pelas enzimas tripsina, quimiotripsina, elastase e carboxipeptidades A e B, e nos enterocitos as enzimas responsaveis sao as endopeptidades, aminopeptidades e dipeptidades. As membranas de borda em escova e basolateral sao atravessadas por aminoacidos e di-tripeptidios mediante mecanismos passivos (difusao simples ou facilitada) ou ativos (cotransportadores de Na+ ou H+). O sistema ativo dependente de Na+ ocorre principalmente na borda em escova e a difusao simples na basolateral. Ambas as membranas apresentam o transporte passivo facilitado. Os aminoacidos livres usam tanto o sistema passivo, como o ativo, enquanto os di-tripeptidios utilizam mais o sistema ativo (H+). A absorcao de proteinas ocorre nos enterocitos, atraves das bordas em escova, ou seja, as microvilosidades absorvem os aminoacidos, dipeptideos, tripeptideos. Alem disso, a absorcao vai depender de alguns fatores, como o transporte ativo, utilizando a ATPase Na/K; difusao facilitada ou ativa. Conclusao: Os mecanismos envolvidos na absorcao de aminoacidos e di-tripeptidios sao revistos diretamente a nutricao humana. Sabendo disso, uma dieta equilibrada e com boas fontes de proteinas de alto valor biologico, acarretara em um bom funcionamento do organismo. Palavras-chave: Absorcao de Proteinas; Digestao; Aminoacidos.

Digestão e absorção de proteínas

Resonance Raman study of sirohydrochlorin and siroheme in sulfite reductases from sulfate reducing bacteria.

In this article we have put together available information on how to determine the structures of the different types of iron-sulfur centers. The discovery of some new basic structures especially the ∣3Fe-3S∣ core has brought a renewed interest into the field of iron-sulfur proteins.

Isabel Moura

Papers

Spectroscopic characterization of a novel 2/(4Fe/4S) ferredoxin isolated from Desulfovibrio desulfuricans ATCC 27774

Iron-sulphur clusters (and other metal-sulphur systems)Desulfovibrio desulfuricans (ATCC 27774) (NIFE) hydrogenase - active sites and reactivity

Digestão e absorção de proteínas

Resonance Raman study of sirohydrochlorin and siroheme in sulfite reductases from sulfate reducing bacteria.

Simple Iron-Sulfur Proteins: Methodology for Establishing the Type of Center