Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>Propane dehydrogenation (PDH) to propene is an important alternative to oil-based cracking processes, to produce this industrially important platform chemical<jats:sup>1,2</jats:sup>. The commercial PDH technologies utilizing Cr-containing (refs. <jats:sup>3,4</jats:sup>) or Pt-containing (refs. <jats:sup>5–8</jats:sup>) catalysts suffer from the toxicity of Cr(<jats:sc>vi</jats:sc>) compounds or the need to use ecologically harmful chlorine for catalyst regeneration<jats:sup>9</jats:sup>. Here, we introduce a method for preparation of environmentally compatible supported catalysts based on commercial ZnO. This metal oxide and a support (zeolite or common metal oxide) are used as a physical mixture or in the form of two layers with ZnO as the upstream layer. Supported ZnO<jats:sub>x</jats:sub> species are in situ formed through a reaction of support OH groups with Zn atoms generated from ZnO upon reductive treatment above 550 °C. Using different complementary characterization methods, we identify the decisive role of defective OH groups for the formation of active ZnO<jats:sub><jats:italic>x</jats:italic></jats:sub> species. For benchmarking purposes, the developed ZnO–silicalite-1 and an analogue of commercial K–CrO<jats:sub><jats:italic>x</jats:italic></jats:sub>/Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> were tested in the same setup under industrially relevant conditions at close propane conversion over about 400 h on propane stream. The developed catalyst reveals about three times higher propene productivity at similar propene selectivity.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Bryozoans (also known as ectoprocts or moss animals) are aquatic, dominantly sessile, filter-feeding lophophorates that construct an organic or calcareous modular colonial (clonal) exoskeleton<jats:sup>1–3</jats:sup>. The presence of six major orders of bryozoans with advanced polymorphisms in lower Ordovician rocks strongly suggests a Cambrian origin for the largest and most diverse lophophorate phylum<jats:sup>2,4–8</jats:sup>. However, a lack of convincing bryozoan fossils from the Cambrian period has hampered resolution of the true origins and character assembly of the earliest members of the group. Here we interpret the millimetric, erect, bilaminate, secondarily phosphatized fossil <jats:italic>Protomelission gatehousei</jats:italic><jats:sup>9</jats:sup> from the early Cambrian of Australia and South China as a potential stem-group bryozoan. The monomorphic zooid capsules, modular construction, organic composition and simple linear budding growth geometry represent a mixture of organic Gymnolaemata and biomineralized Stenolaemata character traits, with phylogenetic analyses identifying <jats:italic>P. gatehousei</jats:italic> as a stem-group bryozoan. This aligns the origin of phylum Bryozoa with all other skeletonized phyla in Cambrian Age 3, pushing back its first occurrence by approximately 35 million years. It also reconciles the fossil record with molecular clock estimations of an early Cambrian origination and subsequent Ordovician radiation of Bryozoa following the acquisition of a carbonate skeleton<jats:sup>10–13</jats:sup>.</jats:p>

<jats:title>Abstract</jats:title><jats:p>The identity of the earliest inhabitants of Xinjiang, in the heart of Inner Asia, and the languages that they spoke have long been debated and remain contentious<jats:sup>1</jats:sup>. Here we present genomic data from 5 individuals dating to around 3000–2800 <jats:sc>bc</jats:sc> from the Dzungarian Basin and 13 individuals dating to around 2100–1700 <jats:sc>bc</jats:sc> from the Tarim Basin, representing the earliest yet discovered human remains from North and South Xinjiang, respectively. We find that the Early Bronze Age Dzungarian individuals exhibit a predominantly Afanasievo ancestry with an additional local contribution, and the Early–Middle Bronze Age Tarim individuals contain only a local ancestry. The Tarim individuals from the site of Xiaohe further exhibit strong evidence of milk proteins in their dental calculus, indicating a reliance on dairy pastoralism at the site since its founding. Our results do not support previous hypotheses for the origin of the Tarim mummies, who were argued to be Proto-Tocharian-speaking pastoralists descended from the Afanasievo<jats:sup>1,2</jats:sup> or to have originated among the Bactria–Margiana Archaeological Complex<jats:sup>3</jats:sup> or Inner Asian Mountain Corridor cultures<jats:sup>4</jats:sup>. Instead, although Tocharian may have been plausibly introduced to the Dzungarian Basin by Afanasievo migrants during the Early Bronze Age, we find that the earliest Tarim Basin cultures appear to have arisen from a genetically isolated local population that adopted neighbouring pastoralist and agriculturalist practices, which allowed them to settle and thrive along the shifting riverine oases of the Taklamakan Desert.</jats:p>