Greater Instability Research Articles

Controlled ovarian stimulation and progesterone supplementation affect vaginal and endometrial microbiota in IVF cycles: a pilot study

PurposeDoes controlled ovarian stimulation (COS) and progesterone (P) luteal supplementation modify the vaginal and endometrial microbiota of women undergoing in vitro fertilization?MethodsFifteen women underwent microbiota analysis at two time points: during a mock transfer performed in the luteal phase of the cycle preceding COS, and at the time of fresh embryo transfer (ET). A vaginal swab and the distal extremity of the ET catheter tip were analyzed using next-generation 16SrRNA gene sequencing. Heterogeneity of the bacterial microbiota was assessed according to both the Bray-Curtis similarity index and the Shannon diversity index.ResultsLactobacillus was the most prevalent genus in the vaginal samples, although its relative proportion was reduced by COS plus P supplementation (71.5 ± 40.6% vs. 61.1 ± 44.2%). In the vagina, an increase in pathogenic species was observed, involving Prevotella (3.5 ± 8.9% vs. 12.0 ± 19.4%), and Escherichia coli-Shigella spp. (1.4 ± 5.6% vs. 2.0 ± 7.8%). In the endometrium, the proportion of Lactobacilli slightly decreased (27.4 ± 34.5% vs. 25.0 ± 29.9%); differently, both Prevotella and Atopobium increased (3.4 ± 9.5% vs. 4.7 ± 7.4% and 0.7 ± 1.5% vs. 5.8 ± 12.0%). In both sites, biodiversity was greater after COS (p < 0.05), particularly in the endometrial microbiota, as confirmed by Bray-Curtis analysis of the phylogenetic distance among bacteria genera. Bray-Curtis analysis confirmed significant differences also for the paired endometrium-vagina samples at each time point.ConclusionsOur findings suggest that COS and P supplementation significantly change the composition of vaginal and endometrial microbiota. The greater instability could affect both endometrial receptivity and placentation. If our findings are confirmed, they may provide a further reason to encourage the freeze-all strategy.

Los pacientes en hemodiálisis presentan peor equilibrio postural, que se relaciona con el riesgo de caídas

IntroductionPostural balance is the result of a complex interaction of sensory input which keeps us upright. Haemodialysis patients have alterations which can lead to postural instability and a risk of falls. Our objective was to analyse postural stability and its relationship with the risk of falls in haemodialysis patients using a force platform. Material and methodsThis was a prospective cross-sectional study. Postural balance was recorded using a force platform in prevalent haemodialysis patients. We collected epidemiological, dialysis, analytical and treatment data. The incidence of falls was recorded over the 6 months following the tests. The postural stability analysis was performed with a portable strain gauge platform (AMTI AccuGait®) and a specific software unit for stabilometry (Balance Trainer® program). We measured 31 balance parameters; the balance variables used were: Area95; AreaEffect; VyMax; Xrange and Yrange. The stabilometry studies were performed in 3 situations: with eyes open; with eyes closed; and with the patient performing a simultaneous task. We performed one study at the start of the dialysis session, and a second study at the end. Stabilometry was measured in a control group under similar conditions. ResultsWe studied 32 patients with a mean age of 68 years old; of this group, 20 subjects were male and 12 were female. Their mean weight was 74kg, with a mean BMI of 27.6kg/m2. In the controls, there were no significant differences in the stabilometry between the 3 situations studied. Both pre- and post-haemodialysis, patients with closed eyes showed greater imbalance, and there were significant differences with the other situations and controls. We found a significant increase in instability after the haemodialysis session, and greater instability in the 13 patients with diabetes (P<.05). The 4 patients with hyponatraemia (Na<136mmol/l) had worse balance in the simultaneous task situation (P=.038). Various drugs, such as insulin (P=.022), antiplatelet agents (P=.036) and beta-blockers (P=.029), were associated with imbalance. The 10 patients who suffered falls had greater imbalance, Yrange, Xrange, Area95 and AreaEffect, both pre- and post-haemodialysis (P<.05) than those without falls. ConclusionsHaemodialysis patients have alterations which can lead to postural instability and a risk of falls. Prevention programmes which include specific exercises to improve balance could be beneficial in reducing the risk of falls in this population.

Patterns of CAG repeat instability in the central nervous system and periphery in Huntington's disease and in spinocerebellar ataxia type 1.

The expanded HTT CAG repeat causing Huntington’s disease (HD) exhibits somatic expansion proposed to drive the rate of disease onset by eliciting a pathological process that ultimately claims vulnerable cells. To gain insight into somatic expansion in humans, we performed comprehensive quantitative analyses of CAG expansion in ~50 central nervous system (CNS) and peripheral postmortem tissues from seven adult-onset and one juvenile-onset HD individual. We also assessed ATXN1 CAG repeat expansion in brain regions of an individual with a neurologically and pathologically distinct repeat expansion disorder, spinocerebellar ataxia type 1 (SCA1). Our findings reveal similar profiles of tissue instability in all HD individuals, which, notably, were also apparent in the SCA1 individual. CAG expansion was observed in all tissues, but to different degrees, with multiple cortical regions and neostriatum tending to have the greatest instability in the CNS, and liver in the periphery. These patterns indicate different propensities for CAG expansion contributed by disease locus-independent trans-factors and demonstrate that expansion per se is not sufficient to cause cell type or disease-specific pathology. Rather, pathology may reflect distinct toxic processes triggered by different repeat lengths across cell types and diseases. We also find that the HTT CAG length-dependent expansion propensity of an individual is reflected in all tissues and in cerebrospinal fluid. Our data indicate that peripheral cells may be a useful source to measure CAG expansion in biomarker assays for therapeutic efforts, prompting efforts to dissect underlying mechanisms of expansion that may differ between the brain and periphery.

An Appalling Wish to Emancipate: Work as a Common Thread Towards the Middle-Class Woman’s Emancipation

During the Victorian era, a time of pronounced economic growth but also of great instability, a large number of women found themselves facing unexpectedly precarious financial situations. Work, a vital element towards the survival of the individual, proved crucial for the empowerment of the Victorian middle-class woman. In a society where an independent woman was rather atypical, Anne Brontë’s female characters are noteworthy examples of women who used work as a path towards emancipation. The governess and the abused wife both appear to embody a universe of women who experienced ill-treatment, something everyone knew about, but not everyone chose to discuss.

Modularity-Based Incremental Label Propagation Algorithm for Community Detection

Label Propagation Algorithm (LPA) is a fast community detection algorithm. However, since each node is randomly assigned a different label at first, there is serious randomness in the label updating process of LPA, resulting in great instability of detection results. This paper proposes a modularity-based incremental LPA (MILPA) to address this problem. Unlike LPA, MILPA first assigns all nodes the same label, and then repeatedly uses divide strategy to split locally dense connected nodes into a community and give them a new label. After that, MILPA uses modularity gain as the optimization function to fine-tune the label of nodes so as to obtain an optimal partition. The proposed MILPA has been compared with LPA and other known methods. Experimental results show that MILPA has the best and most stable performance in LFR benchmark networks and is comparable to the best algorithm in many real networks.

Imbricación y disolución de la masa en el público, sus consecuencias: la inestabilidad política de los sistemas liberales

Un rápido vistazo a las actuales coyunturas políticas en los sistemas políticos liberales que con tanto éxito estuvieron organizando hasta la última crisis económica del 2008 a las sociedades occidentales desde la conclusión de la II Guerra Mundial, permite comprobar el estado más o menos caótico en el que se encuentran muchos de ellos. Lo que en otros tiempos fue con contadas excepciones un remanso político bipartidista de alternancias entre dos fuerzas políticas mayoritarias y hegemónicas, hoy es un galimatías de fuerzas políticas atomizadas y dispersas en todo el espectro político. Sin quitar su responsabilidad a la crisis, existen determinadas causas relacionadas con los cambios en la composición social de la Opinión Pública y la irrupción de las nuevas Tecnologías de la Información y la Comunicación que explican la gran inestabilidad que se ha apoderado de los sistemas políticos occidentales. La presente investigación cualitativa desarrolla una pertinente argumentación explicativa que revela la forma en la que los cambios institucionales han venido afectando a la tradicional esfera social pública, desde la que todavía se legitiman los gobiernos de los sistemas liberales durante los procesos políticos.

The role of sagittal alignment in predicting major failure of lumbopelvic instrumentation: a biomechanical validation of lumbopelvic failure classification.

Finite element analysis. To biomechanically validate the classification of lumbopelvic fixation failure using an in silico model. Even though major failure of lumbopelvic constructs has occurred more often in patients with suboptimal lumbar lordosis and sagittal balance, there has been no biomechanical validation of this classification. Finite element models (T10-pelvis) were created to match the average spinal-pelvic parameters of two cohorts of patients reported in Cho et al. (J Neurosurg Spine 19:445-453, 2013): major failure group (defined as rod breakage between L4 and S1, failure of S1 screws and prominence of iliac screws requiring removal) and non-failure group. A moment was applied at the T10 superior endplate to simulate gravimetric loading in a standing position. Due to differences in the alignment of spinopelvic parameters between normal and failed spines in the presence of a fixed gravity line, the major failure cohort in this study observed a 20% higher load and 18% greater instability. As a result, the rod and screw stress in the major failure cohort increased by 20% and 42%, respectively, in comparison to the non-failure cohort. The greater mechanical demand on the posterior rods in the lower lumbar spine in the major failure cohort further emphasizes the importance of proper sagittal alignment. This finite element analysis validates the classification of lumbopelvic fixation failure.

Preferential Subgenome Elimination and Chromosomal Structural Changes Occurring in Newly Formed Tetraploid Wheat—Aegilops ventricosa Amphiploid (AABBDvDvNvNv)

Artificial allopolyploids derived from the genera Triticum and Aegilops have been used as genetic resources for wheat improvement and are a classic example of evolution via allopolyploidization. In this study, we investigated chromosomes and subgenome transmission behavior in the newly formed allopolyploid of wheat group via multicolor Fluorescence in situ hybridization (mc-FISH), using pSc119.2, pTa535, and (GAA)7 as probe combinations, to enabled us to precisely identify individual chromosomes in 381 S3 and S4 generations plants derived from reciprocal crosses between Ae. ventricosa (DvDvNvNv) and T. turgidum (AABB). A higher rate of aneuploidy, constituting 66.04–86.41% individuals, was observed in these two early generations. Of the four constituent subgenomes, Dv showed the highest frequency of elimination, followed by Nv and B, while A was the most stable. In addition, structural chromosomal changes occurred ubiquitously in the selfed progenies of allopolyploids. Among the constituent subgenomes, B showed the highest number of aberrations. In terms of chromosomal dynamics, there was no significant association between the chromosomal behavior model and the cytoplasm, with the exception of chromosomal loss in the Dv subgenome. The chromosome loss frequency in the Dv subgenome was significantly higher in the T. turgidum × Ae. ventricosa cross than in the Ae. ventricosa × T. turgidum cross. This result indicates that, although the D subgenome showed great instability, allopolyploids containing D subgenome could probably be maintained after a certain hybridization in which the D subgenome donor was used as the maternal parent at its onset stage. Our findings provide valuable information pertaining to the behavior patterns of subgenomes during allopolyploidization. Moreover, the allopolyploids developed here could be used as potential resources for the genetic improvement of wheat.

Inflation Targets Regime and global financial cycle: An assessment for the Brazilian economy

In light of the global financial cycle (GFC), this paper investigates the effectiveness of monetary policy in Brazil since the adoption of the inflation targeting regime. The theoretical section analyses monetary policy from the New Macroeconomic Consensus perspective, emphasizing the implications of the GFC. It also contrasts central bank theory with the post-Keynesian critique. For the empirical investigation, a Markov-switching vector autoregressive model is estimated from January 2000 to December 2017, combining the common variables from the empirical literature with the proxy for the GFC. The main results suggest that greater financial instability has a direct effect on domestic inflation . JEL codes : C14, E12, E42

The Vienna Initiative as an Example of Cross-Border Policy Coordination – Case of Bosnia and Herzegovina

At the very beginning of global economic and financial crisis, foreign capital started to withdraw from banking sector of Bosnia and Herzegovina. There was a huge danger that the domestic banking sector would suffer great instability due to high exposure to foreign investors. The big part of foreign funds was in the form of hot money, and the European banks highly exposed to Central and Southeast Europe had to act. EBRD and IMF launched a rescue plan aimed to slow down the deleveraging process and to preserve financial stability. The foreign banks promised that the pace of funds withdrawal would be accommodated to the preserving of home countries financial stability. The meeting about this issue was held in Vienna, which is an international banking hub for part of Central and especially for Southeast Europe. According to the meeting’s place, rescue plan got the name Vienna Initiative (VI). VI was a cross-border activity with the final aim to reduce systematic risks appeared because of the withdraw of foreign capital from BH banking sector. In this view, VI was specific m macroprudential tool for keeping financial stability. In addition, in a broader view, it was cross-border macroprudential policy coordination plan. For Bosnia and Herzegovina, the Vienna Initiative came in the right moment. Without VI it would be very hard or maybe even impossible for Bosnia and Herzegovina to preserve financial stability and to prevent the balance of payment crisis, and even currency crisis and banking crisis. Thus, in the case of BH, VI was very successful cross-border policy coordination due to the large exposure of domestic banking sector to the foreign investors. At the pick of crisis foreign liabilities of BH banking sector were 6 billion BAM (12/2008) i.e. 32,5% of total liabilities or 29% of total asset. All developed models show that foreign liabilities have a great influence on loans, deposits, and industrial production. The unexpected fall in foreign liabilities would have adverse and very strong effects on deposits, loans, and industrial production. All models show that foreign liabilities significantly affect economic and financial activity in Bosnia and Herzegovina. We used different techniques to show influences of foreign liabilities on domestic variables; Vector autoregression in level and in differences, Vector error correction model, Conditional VAR, and multiple regression models. All models show that in case of disorderly withdrawal of foreign funds, fall in industrial production, deposits, and loans would be much higher than in the case when VI is applied. The main conclusion of the article is that VI helped BH to avoid huge and long negative credit growth i.e. credit crunch, and to avoid deeper economic crisis.

The structure and state of coenopopulations of the rare species &lt;i&gt;Hedysarum gmelinii&lt;/i&gt; Ledeb. (Fabaceae) in different parts of the range

The paper studies the ontogenetic structure features of coenopopulations of a rare representative Hedysarum gmelinii Ledeb. (Fabaceae) on the periphery of the range (the Middle Volga and the Bashkir pre-Urals) and in its central part (the Altai Mountains). The main demographic indicators are determined - the age index and the aging index. Taking demographic indicators into account, the types of coenopopulations were determined according to the delta-omega criterion: in the Bashkir pre-Urals they are mostly young, transitional in the Middle Volga region, and mature in the Altai Mountains. In habitats with great moisture in populations, an increase in the proportion of regenerative individuals was noted. Anthropogenic load (mainly in the form of grazing) has a greater impact on the number and density of individuals, but not on the type of ontogenetic spectrum of coenopopulations. The spatial and ontogenetic structure of coenopopulations of H. gmelinii is characterized by a rather high variety of ontogenetic spectra types (and types of populations, respectively) in the European part of the species range. Differences in the demographic parameters of the populations of the Samara and Orenburg Regions from the populations of the Bashkir pre-Urals and the Altai Mountains were revealed, which is associated with the difference in climatic conditions (primarily the degree of moisture). Features of the organization of H. gmelinii populations indicate their greater instability on the border of the range.

A Review of Rotating Stall in Vaneless Diffuser of Centrifugal Compressor

At present, off-design centrifugal compressor suffers from great instabilities, such as rotating stall and surge, which lead to work failure, strong pressure fluctuations, and violent vibrations of the entire system. One cause of these instabilities is the rotating stall occurring in vaneless diffuser. In this review, recent researches on rotating stall of vaneless diffuser in centrifugal compressor are reviewed, and its inductive mechanism and characteristic description are emphatically introduced. In vaneless diffuser, the rotating stall starts up and fully develops under non-design conditions with the characteristic of increasing pressure fluctuation amplitude. The negative effects of rotating stall include reverse flow and vortex, both of which have significant effects on the instability of centrifugal compressors. Some improvement methods of rotating stall are also introduced, and a lot of examples are given. Finally, some suggestions and discussions are put forward for the future work.

Identite, Mobilite Sociale et Economie: Quelle France Avons-Nous Aujourd’hui?

: This article shows that France is a country of values, which respects its inhabitants who are proud of their nationality, even though they claim their rights. Starting with an understanding of the concepts of nation, state and identity, we consider the existence of a French people who respect the values defended by the European Union. Social mobility, the weakening of the social bond, the employment crisis and the work crisis come together to promote the rise of the far right.After May 68, we are witnessing demands for yellow vests and terrorist acts which cause great instability throughout France.With this work, we discover that the economic and social crisis, the terrorist attacks and the yellow vests are shaking the country and that, despite everything, the French are recovering with increasing security.

Instability Mechanism of Cavity‐Bearing Formation under Tunnel Excavation Disturbance

Urban subway construction inevitably causes disturbances to the rock strata. It can even cause ground collapse accidents when construction encounters a bad geological body in the stratum. To verify the influence of cavities on surface settlement and the mechanism of formation instability, the instability mechanism of cavity‐bearing strata under tunnel excavation disturbance was herein studied by tests using self‐designed indoor models and numerical simulations. This study was based on the concrete project case of Qingdao Metro. Two groups of experiments (with and without cavities) were designed to simulate the four‐step excavation by staged unloading of an airbag. The results show that the settlement value in the cavity state was about twice as much as that in the nonvoid state at the same stage. Besides the first step of excavation, in the numerical simulation, the settlement value of the same stage is about 1.3 times that of the model test. Simulating the deformation process of the surrounding rock in model tests shows that, in the excavation of the tunnel, the collapse surface of the tunnel arch roof will be connected with the sliding surface of the formation cavity. The cavity will gradually change from a regular circle to an ellipse or may even close, resulting in a sudden increase in land subsidence or even ground collapse. This indicates that disturbance during tunnel excavation would cause greater instability in a stratum when bad geological bodies, such as cavities, exist in the stratum.

Instability and Stability in the Population Dynamics of Chukotka and Its Settlements in the Post-Soviet Period: Regional Features and Intraregional and Local Differences

The study is aimed at identifying geographical features and differences in the stability/instability of the population and settlement pattern of one ethnic region in the Russian Arctic, the Chukotka Autonomous Okrug, and the factors that determine them. The use of classical geographical methods, including field research, made it possible to establish that, on the general instability of the population and settlement pattern of Chukotka in the 1990s and stabilization after 2002, significant intraregional and local differences were observed. Chukotsky district has been characterized by relatively greater stability (a smaller decrease in population due to smaller migration outflow and the absence of liquidated settlements) owing to the high share of the indigenous population. The greatest instability, especially in the 1990s, was demonstrated by the district with a large proportion of newcomers and development of the mining industry. The situation was extremely unstable in single-industry urban-type settlements closely associated with mining enterprises, most of which were liquidated before 2000. Differences in the stability/instability of both the status of the population and settlement pattern and differences in resilience/vulnerability as properties inherent to these systems at all spatial levels (from regional to individual settlements) are more pronounced during years of crisis and are smoothed out during periods of relatively stable development.

Staging Revolution: Artistry and Aesthetics in Model Beijing Opera During the Cultural Revolution by Xing Fan

Reviewed by: Staging Revolution: Artistry and Aesthetics in Model Beijing Opera During the Cultural Revolution by Xing Fan John B. Weinstein STAGING REVOLUTION: ARTISTRY AND AESTHETICS IN MODEL BEIJING OPERA DURING THE CULTURAL REVOLUTION. By Xing Fan. Hong Kong: Hong Kong University Press, 2018. xiii + 288 pp. Cloth, US $65.00. Xing Fan begins Staging Revolution: Artistry and Aesthetics in Model Beijing Opera during the Cultural Revolution with a performance anecdote. She recounts the night in 2001 when she saw The Red Lantern, among the most famous of the ten model jingju, performed at the Yisu Grand Theatre in Xi'an. (Though the term jingju has often been translated into English as Peking Opera or Beijing Opera, Fan joins the growing number of scholars who choose to call it jingju.) That night in Xi'an, a packed crowd of over a thousand intently watched the production, at times singing along, at other times discussing with fellow audience members how this night's cast compared with the original cast that had premiered The Red Lantern during the Cultural Revolution, when the ten model jingju were part of the eighteen Model Revolutionary Works (geming yangbanxi) considered exemplary by the Chinese Communist Party of the People's Republic of China. Far from a historical artifact of a time period many would prefer to forget, The Red Lantern was a living, flourishing work of art. The phrase "work of art" is key. Fan's opening anecdote sets the stage for her eventual assertion that these model jingju had, and still have, artistic merit. Raising that assertion to a higher abstraction, Fan writes, "In this context, I argue that literature and art in service of politics are not automatically devoid of literary or artistic merit" (p. 3). Fan's assertion definitely ran contrary to my own previous perceptions of these works; I had subscribed to a not infrequent scholarly view that model jingju were simplistic political works viewers only enjoyed watching because they were required to do so. I sheepishly say this having even co-translated The Red Lantern for a major anthology. Working her way through each element of model jingju—script, acting, music, design, and directing—Fan demonstrates, in extensive detail, how the highly trained and deeply earnest jingju artists created artistic merit in the new model jingju. That is the most significant accomplishment of this book, brought about through extensive archival and interview-based research with the original creators of the works. [End Page 267] In part I, entitled "Jingju, Modern Jingju, and Model Jingju," Fan recounts the development of jingju against a historical and political background roughly spanning 1940 to 1970; each chapter in this part concludes with an extensive example from a selected play. In chapter 1, "Jingju at Yan'an," Fan disputes Mao Zedong's claims that jingju was revolutionized in Yan'an, both because traditional repertory still dominated, and because changes made for newer jingju were in content only, not form. Fan's concluding example, from the 1944 work Driven to Join the Liang Mountain Rebels, illustrates how, without an artistic way to make the masses' viewpoint more central than the classic hero's, there was no revolution in form to match the revolution in content. Chapter 2, "Jingju during the Xiqu Reform," recounts challenges of reforming xiqu (the larger genre encompassing jingju among other regional forms) in the early years of the PRC, a time period marked by discussions of whether modern lives could be presented through jingju's signature style. Ma Yanxiang advocated for comprehensive reform of each element, and the chapter concludes with Fan's analysis of Ma's many innovations in script, performance, and music when directing Three Mountains, which premiered in 1956. Chapter 3, "Modern Jingju in Years of Uncertainty," looks at the period from 1956 to 1963, a time period of great political instability and vacillation. By 1963, the debate over whether it was possible to portray modern life through jingju was over, and focus shifted to how to make it happen artistically, with music, singing, and speech all contested areas. The chapter concludes by analyzing the artistic choices made in developing The White-Haired Girl to portray modern characters convincingly while...

Análise dos investimentos na capacidade de inovar nos indicadores de risco das empresas brasileiras

Investment in the ability to innovate has become a recurrent strategy for companies that seek to lead the market where they operate. However, all investment is also composed by risk that tends to direct and assist stakeholders in its possible return. Taking risks and measuring the uncertainties resulting from the decisions taken is an innate task for the investor who will be guided through indicators to make the decisions considered correct at a given moment. The objective of this study is to evaluate the impact of investments in the ability to innovate on the risk indicators of the 146 largest Brazilian companies listed in B3 (Brasil Bolsa Balcao) in the period from 2012 to 2015, a period characterized by strong political and economic issues. Based on the quantitative approach, composed of innovation and risk indicators, and based on the linear regression model with panel data, it was verified that the variables don’t follow a linear pattern, at times presenting a certain relation, either positive or negative, and sometimes the opposite. This fact can be due to the dispersion of analyzed data or the present contingencies in the environment in which each company is inserted as the analyzed period was of a great political and economic instability influencing adversely in the organizational scenery.

A new formulation of the protective coating for historical monuments

Historic buildings are more closely tied to the ground than modern buildings. They are more porous, take water from the ground, transport it through their structure and evacuate it, generating side effects such as oxidation and crumbling. Walls and floors are the point of exchange for these reactions. An increase in the soil moisture could lead to a greater circulation of dissolved salts, and therefore to a harmful crystallization on the decorated surfaces but also to a greater instability of the soil. Our objective in this work is the choice of a plaster coating to limit damage due to climatic factors and mainly humidity. We are characterized the coating compositions firstly, and then proposed plaster based formulations. The choice of the best plank may be made by carrying out Karsten tube penetration and capillary absorption tests.

A legislação canônica da escolha dos bispos no primeiro milênio

Um dos temas de maior importância na história da Igreja, sem dúvida é a designatio episcoporum, isto é, a escolha dos bispos. Durante o primeiro milênio, é possível encontrar inúmeras fontes que abordam as diversas eclesiologias, formas e sistemas das escolhas episcopais. Desde o contexto do Novo Testamento, passando pelos séculos seguintes, seja em âmbito consuetudinário ou legislativo, dentro e fora da Igreja, nos mostra que a escolha do bispo, era um tema primordial na Igreja e na sociedade. Essa problemática, seja abordada no âmbito dos concílios, dos escritores eclesiásticos, ou até mesmo por meio das determinações por parte do poder temporal, era foco de grande responsabilidade e interesse de imperadores, reis, príncipes, nobres, etc. Por parte da Igreja, houve grande preocupação em abster-se de influencias negativas por parte do poder civil e dos eclesiásticos que não respondiam a uma verdadeira evangelização, como pode-se observar nos textos da patrologia, nas legislações conciliares, etc. Por outro lado, havia o grande interesse do poder temporal nas escolhas episcopais, que lhes garantiriam um grande status, não tendo em um primeiro momento, uma preocupação espiritual, como tal, mas simplesmente com interesses mundanos. Portanto, essa é uma história marcada por tensões, conflitos e de muita instabilidade que sempre esteve presente nas escolhas dos candidatos ao episcopado.

An air-stable binary Ni(0)–olefin catalyst

Nickel catalysis has become a growing and empowering area of research in recent years, providing new reactivity modes towards organic synthesis. In these endeavours, Ni(COD)2 (bis(1,5-cyclooctadiene)Ni(0)) vastly dominated this area, thus becoming the main source of Ni(0) for exploring new catalytic reactivity. However, all known Ni(0)–olefin precatalysts suffer from great instability and fast decomposition when exposed to air. With the aim of providing fast and facile technologies for practitioners, herein we report the synthesis, characterization and reactivity of an air stable binary Ni(0)–olefin complex, Ni(Fstb)3. This 16-electron complex features a unique arrangement of simple ligands that shield the nickel centre from oxygen. We demonstrate that Ni(Fstb)3 is an excellent precatalyst in a wide variety of important nickel-catalysed transformations and has unexpected catalytic properties compared with other Ni(0)–olefin complexes. As a general, practical and air-stable Ni(0) precursor, Ni(Fstb)3 represents a solution to a 60-year quest. Nickel complexes are of ever-increasing importance in organic synthesis; however, unstable Ni(COD)2 is still the main Ni(0) source used. Here the authors report a solution to this long-standing issue: an air stable Ni(0) complex that acts as a general precatalyst for numerous nickel-catalysed reactions.