Water oxidation is pivotal in biological photosynthesis, where it is catalyzed by a protein-bound metal complex with a Mn sub(4)Ca-oxide core; related synthetic catalysts may become key components in ...non-fossil fuel technologies. Going beyond characterization of the catalyst resting state, we compare redox and structural dynamics of three representative birnessite-type Mn(Ca) oxides (catalytically active versus inactive; with/without calcium) and the biological catalyst. In the synthetic oxides, Mn oxidation was induced by increasingly positive electrode potentials and monitored by electrochemical freeze-quench and novel time-resolved in situ experiments involving detection of X-ray absorption and UV-vis transients, complemented by electrochemical impedance spectroscopy. A minority fraction of Mn(iii) ions present at catalytic potentials is found to be functionally crucial; calcium ions are inessential but tune redox properties. Redox-state changes of the water-oxidizing Mn oxide are similarly fast as observed in the biological catalyst (<10 ms), but 10-100 times slower in the catalytically inactive oxide. Surprisingly similar redox dynamics of biological catalyst and water-oxidizing Mn(Ca) oxides suggest that in both catalysts, rather than direct oxidation of bound water species, oxidation equivalents are accumulated before onset of the multi-electron O-O bond formation chemistry in Mn(iii)-Mn(iv) oxidation steps coupled to changes in the oxo-bridging between metal ions. Aside from the ability of the bulk oxide to undergo Mn oxidation-state changes, we identify two further, likely interrelated prerequisites for catalytic activity of the synthetic oxides: (i) the presence of Mn(iii) ions at catalytic potentials preventing formation of an inert all-Mn(iv) oxide and (ii) fast rates of redox-state changes approaching the millisecond time domain.
Official development aid – monetary transfers to developing countries to promote social and economic development – reached more than $140 billion in 2016. However, traditional forms of government ...bilateral aid continue to decline, while private aid is rising. Nevertheless, the impact of this aid, including its potential to stimulate economic development through new business formation, remains uncertain. In this study, we examine the impact of three sources of monetary aid flows on formal and informal entrepreneurship. Drawing from the international political economy literature we argue that bilateral aid and private aid are associated with higher levels of informal entrepreneurship, while multilateral aid is accompanied by lower levels. Moreover, we show that bilateral and private aid are linked with lower levels of formal entrepreneurship, while multilateral aid has no impact. The analyses of a panel of 313 observations from 49 countries provide robust support for these arguments.
A binuclear manganese molecular complex (OH2)(terpy)Mn(μ-O)2Mn(terpy)(OH2)3+ (1) is the most prominent structural and functional model of the water-oxidizing Mn complex operating in plants and ...cyanobacteria. Supported on montmorillonite clay and using Ce(IV) as a chemical oxidant, 1 has been reported to be one of the best Mn-based molecular catalysts toward water oxidation. By X-ray absorption spectroscopy and kinetic analysis of the oxygen evolution reaction, we show that (OH2)(terpy)Mn(μ-O)2Mn(terpy)(OH2)3+ is transformed into layered type Mn-oxide particles which are the actual water oxidation catalyst.
Abstract Multisystemic inflammatory syndrome in children (MIS-C) might manifest in a broad spectrum of clinical scenarios, ranging from mild features to multi-organ dysfunction and mortality. ...However, this novel entity has a heterogenicity of data regarding prognostic factors associated with severe outcomes. The present study aimed to identify independent predictors for severity by using multivariate regression models. A total of 391 patients (255 boys and 136 girls) were admitted to Vietnam National Children’s Hospital from January 2022 to June 2023. The median age was 85 (range: 2–188) months, and only 12 (3.1%) patients had comorbidities. 161 (41.2%) patients required PICU admission, and the median PICU LOS was 4 (2–7) days. We observed independent factors related to PICU admission, including CRP $$\ge $$ ≥ 50 (mg/L) (OR 2.52, 95% CI 1.39–4.56, p = 0.002), albumin $$\le $$ ≤ 30 (g/L) (OR 3.18, 95% CI 1.63–6.02, p = 0.001), absolute lymphocyte count $$\le $$ ≤ 2 (× 10 9 /L) (OR 2.18, 95% CI 1.29–3.71, p = 0.004), ferritin ≥ 300 (ng/mL) (OR 2.35, 95% CI 1.38–4.01), p = 0.002), and LVEF < 60 (%) (OR 2.48, 95% CI 1.28–4.78, p = 0.007). Shock developed in 140 (35.8%) patients, especially for those decreased absolute lymphocyte $$\le $$ ≤ 2 (× 10 9 /L) (OR 2.48, 95% CI 1.10–5.61, p = 0.029), albumin $$\le $$ ≤ 30 (g/L) (OR 2.53, 95% CI 1.22–5.24, p = 0.013), or LVEF < 60 (%) (OR 2.24, 95% CI 1.12–4.51, p = 0.022). In conclusion, our study emphasized that absolute lymphocyte count, serum albumin, CRP, and LVEF were independent predictors for MIS-C severity. Further well-designed investigations are required to validate their efficacy in predicting MIS-C severe cases, especially compared to other parameters. As MIS-C is a new entity and severe courses may progress aggressively, identifying high-risk patients optimizes clinicians' follow-up and management to improve disease outcomes.
The synthesis of the first water stable isoreticular phosphonate based mixed-linker metal-organic frameworks (MOFs) is achieved via the use of the N-donor heterocyclic co-ligands. Furthermore, these ...isoreticular phosphonate frameworks show selective CO(2)/N(2) uptake at low pressures.
Co\(_{2}\)TiSi films were grown by molecular beam epitaxy on GaAs(001) and analyzed using reflection high-energy electron diffraction, and electron microscopy. In addition, X-ray diffraction was ...combined with lattice parameter calculations by density functional theory comparing the \textit{L\(2_1\)} and \textit{B}2 structures and considering the influence of non--stoichiometry. Columnar growth is found and attributed to inhomogeneous epitaxial strain from non-random alloying. In films with thicknesses up to 13~nm these columns may be the origin of perpendicular magnetization with the easy axis perpendicular to the sample surface. We found \textit{L\(2_1\)} and \textit{B}2 ordered regions, however the Co/Ti--ratio is changing in dependence of the position in the film. The resulting columnar structure is leading to anisotropic \textit{B}2--ordering with the best order parallel to the axes of the columns.
In the worldwide search for sustainable energy technologies, water oxidation by abundant low-cost materials is of key importance. In nature, this process is efficiently catalyzed by an intricate ...manganese-calcium (Mn4Ca) complex bound to the proteins of photosystem II (PSII). Recently synthetic manganese-calcium oxides were found to be active catalysts of water oxidation but at the atomic level their structure has remained elusive. To investigate these amorphous catalysts, extended-range X-ray absorption spectroscopy (XAS) at the K-edges of both manganese and calcium was performed. The XAS results reveal striking similarities between the synthetic material and the natural Mn4Ca complex. The oxidation state of manganese in the active oxides was found to be close to +4, but MnIII ions are present as well at a level of about 20%. Neighboring Mn ions are extensively interconnected by two bridging oxygens, a characteristic feature of layered manganese oxides. However, the oxides do not exhibit long-range order, as opposed to canonical, but catalytically inactive MnIII- or MnIV-oxides. Two different Ca-containing motifs were identified. One of them results in the formation of Mn3CaO4 cubes, as also proposed for the natural paragon in PSII. Other calcium ions likely interconnect oxide-layer fragments. We conclude that these readily synthesized manganese-calcium oxides are the closest structural and functional analogs to the native PSII catalyst found so far. Evolutionary implications are considered. From the differences to inactive manganese oxides, we infer structural features facilitating the catalysis of water oxidation in both the protein-bound Mn4Ca complex of PSII and in the synthetic oxides.
We measured element concentrations (As, Cd, Cu, Pb, Zn, Fe) and body condition (gross and histologie endpoints) of animals from a caribou (Rangifer tarandus) mortality event that occurred in Alaska, ...in the area of Point Hope and Cape Thompson (including the Chariot site), in 1995. These were compared to results from hunter-killed caribou from reference sites (Barrow and Teshekpuk Lake, Alaska) and from the area of a mine (Red Dog Mine) to determine whether heavy metals had played a role in the mortality event or whether any elements were at concentrations of concern for human consumers. Starvation and malnutrition were major factors leading to death or severe weakness, as very little or no fat (very low body condition scores) and serous atrophy of fat (observed as watery contents of the marrow cavity, with no apparent fat, and histologically) were more prevalent in caribou associated with the mortality event than in hunter-killed animals from reference sites. Accumulation of hepatic (liver) hemosiderin in Kupffer cells (macrophages) was noted as an indicator of cachexia. Concentrations of lead in feces and liver, copper in the rumen contents, and arsenic in muscle were higher in caribou harvested near Red Dog Mine, as might be expected in that mineral-rich area, but were not at levels of concern for toxicoses. Kidney concentrations of cadmium, which increased significantly with increasing age, present a potential concern for human consumers, and this is an expected finding. We concluded that caribou had starved and that heavy metals had played no role in the mortality event. Further investigation of regional mineral differences is required to understand the sources and transport mechanisms that explain these findings and to properly address mining activity. Mortality events on the north slope of Alaska are common and likely involve starvation as described here, but in most cases they are not investigated, even though recent industrial activities have heightened concern among some local residents and wildlife managers. /// On a mesuré la concentration en éléments (As, Cd, Cu, Pb, Zn, Fe) et l'état corporel (points limites bruts et histologiques) de caribous (Rangifer tarandus) prélevés lors d'un épisode de mortalité qui s'est produit en 1995 en Alaska, dans la région de Point Hope et de Cape Thompson (y compris le site Chariot). On a comparé ces résultats à ceux de caribous tués par des chasseurs à des emplacements témoins (Barrow et Teshekpuk Lake, en Alaska) et à proximité d'une mine (Red Dog Mine) pour trouver si les métaux lourds avaient joué un rôle dans l'épisode de mortalité ou si la concentration d'un ou plusieurs éléments pouvait constituer un risque pour la consommation humaine. La famine et la malnutrition étaient des facteurs majeurs ayant causé la mort ou une extrême faiblesse, vu que la présence minime ou l'absence de graisse (très basses notes d'état corporel) et une atrophie séreuse de la graisse (observée sous forme de contenu aqueux de la cavité médullaire, sans graisse visible, et à la suite de l'examen histologique) étaient plus courantes chez le caribou associé à l'épisode de mortalité que chez les animaux des emplacements témoins tués par les chasseurs. On a noté dans le foie une accumulation d'hémosidérine hépatique des cellules de Kupffer (cellules macrophages) témoignant d'une cachexie. La concentration de plomb dans les matières fécales et le foie, de cuivre dans le rumen et d'arsenic dans le tissu musculaire était plus élevée chez le caribou provenant de Red Dog Mine, comme on pouvait s'y attendre dans cette zone riche en minéraux, mais cette concentration n'atteignait pas un niveau pouvant provoquer des toxicoses. La concentration de cadmium dans le rein, qui augmentait de façon significative avec l'âge, pourrait constituer un risque pour la consommation humaine, ce qui n'est pas surprenant. On a conclu que les caribous étaient morts de faim et que les métaux lourds n'avaient joué aucun rôle dans l'épisode de mortalité. Il faudrait effectuer des recherches plus poussées sur les différences régionales en minéraux afin de comprendre les mécanismes d'origine et de transport qui expliquent ces résultats et
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent data suggest that the risk of young-onset colorectal cancer (yCRC), in adults less than 50 years of age, is increasing. To confirm findings and identify contemporary trends worldwide, we ...conducted a systematic review of studies examining population-level trends in yCRC epidemiology.
We searched MEDLINE (1946-2018), EMBASE (1974-2018), CINAHL (1982-2018), and Cochrane Database of Systematic Reviews (2005-2018) for studies that used an epidemiologic design, assessed trends in yCRC incidence or prevalence, and published in English. Extracted information included country, age cut-off for yCRC, and reported trends in incidence or prevalence (e.g. annual percent change APC). We pooled similarly reported trend estimates using random effects models.
Our search yielded 8695 articles and after applying our inclusion criteria, we identified 40 studies from 12 countries across five continents. One study assessed yCRC prevalence trends reporting an APCp of + 2.6 and + 1.8 among 20-39 and 40-49 year olds, respectively. 39 studies assessed trends in yCRC incidence but with substantial variability in reporting. Meta-analysis of the most commonly reported trend estimate yielded a pooled overall APCi of + 1.33 (95% CI, 0.97 to 1.68; p < 0.0001) that is largely driven by findings from North America and Australia. Also contributing to these trends is the increasing risk of rectal cancer as among 14 studies assessing cancer site, nine showed an increased risk of rectal cancer in adults less than 50 years with APCi up to + 4.03 (p < 0.001).
Our systematic review highlights increasing yCRC risk in North America and Australia driven by rising rectal cancers in younger adults over the past two decades.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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