Computer simulations of structures, energetics and dynamics of myoglobin center dot center dot center dot ligand complexes

Myoglobin has been studied in considerable detail using different experimental and computational techniques over the past decades. Recent developments in time-resolved spectroscopy have provided experimental data amenable to detailed atomistic simulations. The main theme of the present review are results on the structures, energetics and dynamics of ligands ( CO, NO) interacting with myoglobin from computer simulations. Modern computational methods including free energy simulations, mixed quantum mechanics/molecular mechanics simulations, and reactive molecular dynamics simulations provide insight into the dynamics of ligand dynamics in confined spaces complementary to experiment. Application of these methods to calculate and understand experimental observations for myoglobin interacting with CO and NO are presented and discussed.

Structures, reactivity, and catalytic activity of dithiolato-bridged heterobimetallic MRh (M = Pt, Pd) complexes

Heterobimetallic complexes [(P−P)Pt(μ-S−S)Rh(cod)]ClO4 (P−P = (PPh3)2, Ph2P(CH2)3PPh2 (dppp), and Ph2P(CH2)4PPh2 (dppb); S−S = -S(CH2)2S- (EDT), -S(CH2)3S- (PDT), -S(CH2)4S- (BDT), cod = 1,5-cyclooctadiene) reacted with CO to form the carbonyl complexes [(P−P)Pt(μ-S−S)Rh(CO)2]ClO4 and then with PR3 ligands to give [(P−P)Pt(μ-S−S)Rh(CO)(PR3)]ClO4. The binuclear framework of these cod complexes was maintained in the reactions reported. The cod complexes were tested as catalyst precursors in the hydroformylation of styrene. HPNMR in situ studies showed that mononuclear species formed under catalytic conditions.

Sterically hindered metal alkenyls. Part 1. Synthesis, reactions, and crystal and molecular structures of some palladium and platinum σ-alkenyls

The compounds trans-[PtBr{C(C10H15)CH2}(PEt3)2](1)(C10H15= adamant-1-yl), trans-[MBr{C(C10H7)CMe2}(PEt3)2][M = Pd (2) or Pt (3); C10H7= naphth-1-yl], and trans-[MBr{C(Ph)CMe2}(PEt3)2][M = Pd (4) or Pt (5)] have been prepared from Grignard [for (2) and (3)] or lithium reagents [for (1), (4), and (5)] and appropriate dichlorobis(phosphine)metal derivatives. Full single-crystal X-ray data are reported for (1) and (3), and reveal unusually long Pt–C(sp2) bonds. Insertion reactions into these M–C bonds occur with MeNC [for (1), (3), and (5)], and with CO [for (1) and (3)]; the latter, the first reported insertion into a Pt–C(sp2) bond, occurs under mild conditions as expected for the abnormally long M–C bonds.

Synthesis and structural characterisation of [Pd2(μ-Br)2(PBut3)2], an example of a palladium(I)-palladium(I) dimer

The syntheses, spectroscopic characterisation and in one case (X = Br) the single-crystal structure of the novel PdI–PdI dimers [Pd2(µ-X)2(PBut3)2](X = Br or I) have been determined; preliminary results on their reactions with CO, H2, CNC6H3Me2 and C2H2 have also been obtained.

Peroxynitrite mediates disruption of Ca2+ homeostasis by carbon monoxide via Ca2+ ATPase degradation

CO stimulates formation of NO and reactive oxygen species which, via peroxynitrite formation, inhibit Ca(2+) extrusion via PMCA, leading to disruption of Ca(2+) signaling. We propose this contributes to the neurological damage associated with CO toxicity.

The effects of dietary nitrate on blood pressure and endothelial function: a review of human intervention studies.

Evidence has accumulated in recent years that suggests that nitrate from the diet, particularly vegetables, is capable of producing bioactive NO in the vasculature, following bioconversion to nitrite by oral bacteria. The aim of the present review was to consider the current body of evidence for potential beneficial effects of dietary nitrate on blood pressure and endothelial function, with emphasis on evidence from acute and chronic human intervention studies. The studies to date suggest that dietary nitrate acutely lowers blood pressure in healthy humans. An inverse relationship was seen between dose of nitrate consumed and corresponding systolic blood pressure reduction, with doses of nitrate as low as 3 mmol of nitrate reducing systolic blood pressure by 3 mmHg. Moreover, the current studies provide some promising evidence on the beneficial effects of dietary nitrate on endothelial function. In vitro studies suggest a number of potential mechanisms by which dietary nitrate and its sequential reduction to NO may reduce blood pressure and improve endothelial function, such as: acting as a substrate for endothelial NO synthase; increasing vasodilation; inhibiting mitochondrial reactive oxygen species production and platelet aggregation. In conclusion, the evidence for beneficial effects of dietary nitrate on blood pressure and endothelial function is promising. Further long-term randomised controlled human intervention studies assessing the potential effects of dietary nitrate on blood pressure and endothelial function are needed, particularly in individuals with hypertension and at risk of CVD.

Effects of dense code-switching on executive control

Bilingualism is reported to re-structure executive control networks, but it remains unknown which aspects of the bilingual experience cause this modulation. This study explores the impact of three code-switching types on executive functions: (1) alternation of languages, (2) insertion of lexicon of one language into grammar of another, (3) dense code-switching with co-activation of lexicon and grammar. Current models hypothesise that they challenge different aspects of the executive system because they vary in the extent and scope of language separation. Two groups of German-English bilinguals differing in dense code-switching frequency participated in a flanker task under conditions varying in degree of trial-mixing and resulting demands to conflict-monitoring. Bilinguals engaging in more dense code-switching showed inhibitory advantages in the condition requiring most conflict-monitoring. Moreover, dense code-switching frequency correlated positively with monitoring skills. This suggests that the management of co-activated languages during dense code-switching engages conflict-monitoring and that the consolidation processes taking place within co-activated linguistic systems involve local inhibition. Code-switching types requiring greater degrees of language separation may involve more global forms of inhibition. This study shows that dense code-switching is a key experience shaping bilinguals’ executive functioning and highlights the importance of controlling for participants’ code-switching habits in bilingualism research.

The ""decarbonization"" of the world`s energy matrix

Decarbonizing the world`s energy matrix is the strategy being implemented by most countries to reduce CO(2) emissions and thus contribute to achieve the ultimate objectives of the Climate Convention. The evolution of the carbon intensity (I(c)=CO(2)/GDP) in the period 1990-2007 was encouraging but not sufficient to reduce the growth of carbon emission. As a result of COP-15 in Copenhagen these countries (and regions) made pledges that could lead to more reduction: for the United States a 17% reduction in CO(2) emissions by 2020 below the level of 2005: for the European Union a 20% reduction in CO(2) emissions by 2020 below the 1990 level: for China a 40-45% reduction in the carbon intensity and for India a 20-25% reduction in carbon intensity by 2020. We analyzed the consequences of such pledges and concluded that the expected yearly rate of decrease of the carbon intensity follows basically the ""business as usual"" trend in the period 1990-2007 and will, in all likelihood, be insufficient to reduce carbon emissions up to 2020. (C) 2010 Elsevier Ltd. All rights reserved.

Effects of the partial replacement of La by M (M=Ce, Ca and Sr) in La(2-x)M(x)CuO(4) perovskites on catalysis of the water-gas shift reaction

The performance of La(2-x)M(x)CuO(4) perovskites (where M = Ce, Ca or Sr) as catalysts for the water-gas shift reaction was investigated at 290 degrees C and 360 degrees C. The catalysts were characterized by EDS, XRD, N(2) adsorption-desorption, XPS and XANES. The XRD results showed that all the perovskites exhibited a single phase (the presence of perovskite structure), suggesting the incorporation of metals in the perovskite structure. The XPS and XANES results showed the presence of Cu(2+) on the surface. The perovskites that exhibited the best catalytic performance were La(2-x)Ce(x)CuO(4) perovslcites, with CO conversions of 85%-90%. Moreover, these perovskites have higher surface areas and larger amounts of Cu on the surface. And Ce has a higher filled energy level than the other metals, increasing the energy of the valence band of Ce and providing more electrons for the reaction. Besides, the La(1.80)Ca(0.20)CuO(4) perovskite showed a good catalytic performance.

Axial ligand influence on geometries, charge distributions and electronic structures of iron tetraazamacrocycle [Fe((II))TIM(X)(Y)](2+) complexes assessed by Density Functional Theory

We employed the Density Functional Theory along with small basis sets, B3LYP/LANL2DZ, for the study of FeTIM complexes with different pairs of axial ligands (CO, H(2)O, NH(3), imidazole and CH(3)CN). These calculations did not result in relevant changes of molecular quantities as bond lengths, vibrational frequencies and electronic populations supporting any significant back-donation to the carbonyl or acetonitrile axial ligands. Moreover, a back-donation mechanism to the macrocycle cannot be used to explain the observed changes in molecular properties along these complexes with CO or CH(3)CN. This work also indicates that complexes with CO show smaller binding energies and are less stable than complexes with CH(3)CN. Further, the electronic band with the largest intensity in the visible region (or close to this region) is associated to the transition from an occupied 3d orbital on iron to an empty pi* orbital located at the macrocycle. The energy of this Metal-to-Ligand Charge Transfer (MLCT) transition shows a linear relation to the total charge of the macrocycle in these complexes as given by Mulliken or Natural Population Analysis (NPA) formalisms. Finally, the macrocycle total charge seems to be influenced by the field induced by the axial ligands. (C) 2011 Elsevier Ltd. All rights reserved.

Tidig föräldrastress hos mammor med för tidigt födda barn

Bakgrund: Att bli mamma till ett för tidigt fött barn (<37 gestationsveckor) innebär en oväntad stress vilket påverkar hela familjen. Under de senaste årtionden har stora förbättringar skett inom perinatal vård och numera är chansen till överlevnad stor. Att barnet efter födseln vårdas på neonatal intensivvårdsavdelning (NICU) får konsekvenser för mamman både känslomässigt och i omvårdnaden av barnet. Syfte: Att undersöka föräldrastress och beskriva faktorer som påverkar tidig föräldrastress hos mammor till för tidigt födda barn när barnet är två månader i korrigerad ålder. Metod: Studien utfördes på fyra NICU i Sverige. Inklusionskriterierna för studien var att barnet var för tidigt fött samt vårdades på neonatalavdelning i minst 72 timmar. För att mäta upplevd föräldrastress fick mammorna (n=276) svara på enkäten Swedish Parental Stress Questionnaire (SPSQ) när barnet var två månader i korrigerad ålder. Resultat: Mammor vars barn inte vårdades på en samvårdsavdelning, som hade barn i kuvös, mammor till barn med äldre syskon, var äldre, rökte och/eller ammade helt upplevde mer föräldrastress än övriga mammor. Slutsats: Studien visar att faktorer i framför allt i miljön samt hos mamman har betydelse för upplevd föräldrastress. Våra resultat innebär att omhändertagandet bör bli bättre, både under tiden på neonatalavdelning men även efter utskrivning. Då studien också påvisar vikten av samvårdsavdelning bör förbättringar ske i den fysiska vårdmiljön för att minimera upplevelsen av föräldrastress.

Acceptabel och effektiv färgreducering i tryck : Utvärdering av färgreduceringsresultat från Alwan CMYK Optimizer ECO

Tryckeribranschen är en ekonomiskt pressad bransch som söker nya besparingsmetoder. En av metoderna är att minska insatsvaran tryckfärg med färgreduceringsprogramvara. Rapporten undersöker möjligheterna med färgreduceringssystem. Detta genom att studera hur man använder sig av färgreducering och hur det påverkar trycket. Studien avser besvara: • Hur stor färgminskning kan man använda sig av utan negativa konsekvenser på bildkvalitén? • Hur går man tillväga för att skapa den färgminskningen? • Överensstämmer total färgförändring och visuell bedömning av tryck? För att få svar på dessa frågor togs en testform fram med nödvändiga bilder och färgfält som sedan genomgick en rad färgreduktioner. Testformen utvärderades digitalt med avseende på TAC och total färgförändring. Därefter trycktes testformen och utvärderades visuellt av en testgrupp och uppmättes för att visa färgförändring efter tryck. Resultatet av undersökningen visar att det går att färgreducera tryck utan avsevärda negativa konsekvenser på bildkvalitén. En reducering från 300 % TAC till en TAC mellan 240 % och 210 % är fullt möjlig för att få en besparing och vara inom standard för total färgförändring. Detta går att göra väldigt lätt med en programvara som Alwan CMYK Optimizer ECO, med enbart förvalda inställningar och en inställd Total Ink Limit mellan 240 % och 210 %. Resultatet visade även en stark korrelation mellan den visuella bedömningen och den totala färgförändring, som tyder att både metoder är lämpliga för bedömning av tryck.

Turismo sustentável e alivio a pobreza: avaliação de impacto

This study evaluates the social impacts of the project PRODETUR in Porto Seguro and Bahia. Among the analyzed channels, we have focused on the impact on variables related to sewering (access to piped water, sewer and garbage collection), besides some socio-economic ones (occupation, contribution to social security, income and poverty). In addition, we analyzed the impact on the distribution of costs and benefits between the immigrant and native population. Using the methodology of differences-in-differences to compare areas affected and non–affected by the program, we measured the “true” impact of the program using the 1991 and 2000 Census. The results suggest a relative advance in Porto Seguro in what concerns employment, formality, income and poverty reduction, with this benefits being uniformly distributed between immigrant and native population. On the other hand, we have observed a relative worsening in the sanitary situation, what will lead to future problems whose cost will be beard mainly by the natives, among which we observe a relative worse access to water, sewer and garbage collection. Therefore, we conclude that, in order to provide tourism in a sustainable way, the municipality of Porto Seguro requires a better preservation of its natural capital.

Diz-me quanto ganhas e te direi como te sentes: análise do overpayment no funcionalismo público no Brasil

O contexto do funcionalismo público como fonte empregadora tem chamado crescente atenção, uma vez que as práticas de remuneração acima da média de mercado adotadas neste contexto vêm atraindo cada vez mais indivíduos altamente qualificados (Bender & Fernandes, 2006). Entretanto, trata-se de um setor que adota práticas de remuneração que também são caracterizadas pela desigualdade, uma vez que carreiras bem remuneradas co-existem com outras mal remuneradas, por vezes, dentro do mesmo espaço organizacional e executando tarefas similares. Estudos demonstram que, a priori, um ambiente de trabalho que favorece uma situação de desigualdade afeta negativamente diversos aspectos comportamentais dos funcionários que nele exercem atividades (e.g. De Cremer & Van Kleef, 2009; Peters & Van den Bos, 2008; Peters, Van den Bos & Bobocel, 2004). Desta forma, o presente estudo buscou entender como uma situação de desigualdade remuneratória – em que alguns membros se encontram em uma situação de overpayment, enquanto que outros na situação de underpayment – pode influenciar fatores como a autoestima e o comprometimento afetivo dos funcionários públicos com relação aos seus trabalhos. Um órgão público do Poder Executivo Federal, foi escolhido como lócus de pesquisa para analisar estes impactos. A metodologia utilizada na pesquisa teve uma natureza quantitativa e qualitativa. Numa primeira etapa, aplicaram-se 105 questionários a dois grupos distintos de servidores desse órgão público (um grupo tido como overpaid e outro tido como underpaid), tendo sido analisadas, por meio de regressões hierárquicas, os impactos da percepção de justiça salarial na auto-estima e no comprometimento dos funcionários. Posteriormente, realizaram-se 20 entrevistas com funcionários dos dois grupos com o intuito de aprofundar e discutir aspectos mais sensíveis relacionados com os resultados. Dessas análises foi possível confirmar a influência direta do senso de justiça remuneratória que o indivíduo possui na sua auto-estima e no seu comprometimento afetivo. Os resultados da pesquisa demonstram que representantes das carreiras bemremuneradas tendem a comparar-se com outras carreiras melhor remuneradas, evitando a comparação com os colegas do trabalho pertencentes a carreiras menos favorecidas. Entretanto, a influência que o sentimento de justiça tem em ambos os resultados comportamentais analisados é potencializada quanto maior for a percepção do indivíduo acerca da satisfação dos seus pares com o trabalho e com a sua remuneração. Observou-se ainda o efeito moderador da motivação epistêmica nesta relação. Esta pesquisa espera ter contribuído para melhor entender os impactos que políticas salariais podem ter nos funcionários públicos.

Brachiaria decumbens supresses the initial growth of Coffea arabica

Brachiaria decumbens vem se tornando uma das plantas daninhas mais freqüentes na infestação de cafezais em formação, pois além de sua elevada agressividade e dificuldade de controle, está ocorrendo expansão das áreas cafeeiras para locais anteriormente ocupados por pastagens. Objetivou-se neste trabalho avaliar os efeitos desta planta daninha, em densidades crescentes, sobre o desenvolvimento inicial de mudas de café (Coffea arabica L. cv. Catuaí Amarelo). O experimento foi conduzido em condições semi-controladas, sem limitação de água. Uma muda de café foi transplantada em caixa de amianto com capacidade para 70 L, preenchida com terra coletada da camada arável de um Latossolo Vermelho. Os tratamentos constaram de diferentes densidades de transplante de capim-braquiária, a saber: 0, 4, 8, 12, 16, 20, 24, 36, 48 e 60 plantas m-2. O ensaio foi conduzido por um período experimental de 120 dias após o plantio (DAP). Todas as características analisadas foram afetadas negativamente pela interferência da planta daninha, mas as que se mostraram mais sensíveis a essa interferência foram à área foliar e a biomassa seca das folhas. Houve redução de 41,8% na área foliar do cafeeiro quando conviveu com o capim-braquiária a partir da densidade de 8 plantas m-2, chegando a 68,7% na densidade de 60 plantas m-2. Também a partir da densidade de 8 plantas m-2, a redução na biomassa seca das folhas em relação à testemunha foi de 41,4% e na densidade de 60 plantas m-2 chegou a 72,8%. Brachiaria decumbens, a partir da densidade de 8 plantas m-2, interfere negativamente sobre as mudas de café até os 120 DAP.