bluuebunny/crossref_metadata_2025 huggingface dataset:
Heritage Outreach, Fossils, Dinosaurs and Sites: How Locals’ Perception Changes After 10 Years of Actions in Historic Urban Villages (Cuenca, Spain)
Authors: de la Cita Lara , Llandres Mercedes , Buscalioni Ángela D.
Published: June 2021

Cuenca, a small city with a rich historical and palaeontological heritage, is the ideal location to explore how the scientific knowledge of its inhabitants has changed over the years. In 2010 and 2019, two surveys were conducted on the streets of Cuenca to characterise their scientific profiles and how they perceive heritage outreach initiatives in palaeontology (i.e. visits and non-formal education in museums, research dissemination and mass media). For the present study, 320 responses were analysed through multivariate techniques (multiple correspondence analysis or MCA), using simple binary states and multiple nominal states. The results showed a significant disparity in the age demographic category: on the one hand, young people (< 18 years old) retained more scientific information linked to educational activities than older people in 2010; on the other hand, older Cuenca natives (> 55 and 35–55 years old) were the most informed and influenced by outreach and media in 2019, some of them even forming a particular group of palaeontology and dinosaur enthusiasts, herein named ‘paleo-geeks’. In general, it was found that the majority of answers were congruent within the same year and corresponded with the sociocultural changes that Cuenca had experienced, from a rural to a more urban and diverse culture. Lastly, it was concluded that heritage outreach initiatives do influence the scientific profiles of Cuenca’s inhabitants.
Geometrisches Begriffsverständnis in der Grundschule am Beispiel der Begriffe Viereck, Rechteck und Quadrat
Authors: Bruns Julia , Unterhauser Elisabeth , Gasteiger Hedwig
Published: June 2021

Zu den ersten geometrischen Begriffen, die Kinder bereits im Elementar- und Primarbereich lernen, zählen u. a. Viereck, Rechteck und Quadrat. Studien zeigen, dass Lernende bereits früh individuelle Vorstellungen, sog. individuelle Begriffskonzepte, zu diesen Begriffen aufbauen. Zwar wird die Entwicklung von Begriffsverständnis in verschiedenen mathematikdidaktischen Stufenmodellen dargestellt, diese sind jedoch generisch und beschreiben nicht explizit die Entwicklung der ersten individuellen Begriffskonzepte von Lernenden zu Viereck, Rechteck und Quadrat. Aus empirischer Sicht liegen verschiedene Studien vor, die einzelne Aspekte der individuellen Begriffskonzepte von Lernenden unterschiedlicher Altersgruppen zu diesen Begriffen ausleuchten. Um Begriffsbildungsprozesse aus empirischer Sicht detaillierter entlang der jeweils vorherrschenden individuellen Begriffskonzepte zu beschreiben, fehlen insbesondere Studien in der Grundschule, die alle vier Klassenstufen betrachten und dabei differenzierte Erkenntnisse zu verschiedenen theoretischen Indikatoren des Begriffsverständnisses liefern. Daher geht die vorliegende Studie der Frage nach, welches Verständnis der Begriffe Viereck, Rechteck und Quadrat Schülerinnen und Schüler der Jahrgangsstufen 1, 2, 3 und 4 zeigen. Dazu wurde eine Quasi-Längsschnittstudie mit N = 456 Grundschulkindern (ca. 100 pro Jahrgangsstufe) durchgeführt. Die Ergebnisse geben detaillierte Einblicke in die individuellen Begriffskonzepte der Lernenden und zeigen, dass Lernende zunehmend Eigenschaften der Figuren berücksichtigen, jedoch individuelle Begriffskonzepte über lange Zeit auch prototypisch geprägt sind. Implikationen dieser Ergebnisse für Forschung und Praxis werden diskutiert.
How unnecessarily high abatement costs and unresolved distributional issues undermine nutrient reductions to the Baltic Sea
Authors: Andersson Anna , Brady Mark V. , Pohjola Johanna
Published: June 2021

This paper systematically reviews the literature on how to reduce nutrient emissions to the Baltic Sea cost-effectively and considerations for allocating these costs fairly among countries. The literature shows conclusively that the reduction targets of the Baltic Sea Action Plan (BSAP) could be achieved at considerably lower cost, if countries would cooperate to implement the least costly abatement plan. Focusing on phosphorus abatement could be prudent as the often recommended measures—wastewater treatment and wetlands—abate nitrogen too. An implication of our review is that the potential for restoring the Baltic Sea to good health is undermined by an abatement strategy that is more costly than necessary and likely to be perceived as unfair by several countries. Neither the BSAP nor the cost-effective solution meet the surveyed criteria for fairness, implying a need for side-payments.
Investigation of the heat distribution in dry friction systems during fade and recovery using fiber-optic sensing and infrared technology
Authors: Albers Albert , Klotz Thomas , Fink Chris , Ott Sascha
Published: June 2021

The design of dry-running friction pairings and systems determines not only their installation space and costs, but also their reliability under critical load conditions, for example in emergencies, in the case of faults, and in the event of misuse. While knowledge of the contact pattern is highly important for the development of clutches and brakes, the contact-related measurement of the temperature of these systems has not yet been solved in a satisfactory manner. Despite its importance, the temperature distribution has only been measured in a few studies. Typically, temperature measurements of complete clutches and brakes are carried out using thermocouples only. In this study, a new innovative test setup is presented. This setup is able to measure the heat distribution of the lining and the steel disk of a brake with high spatial resolution by means of fiber optic sensing technology and thermography. As a novelty, it enables measurement of the heat distribution and allows to correlate it with the fade and recovery behavior. Contrary to the expectations, the contact pattern is heterogeneous in circumferential direction. Possible causes are discussed using simulation results. Along with surface analysis, the new setup contributes to the investigation of the causes of fade and recovery.
Consistent Alterations of Human Fecal Microbes After Transplantation into Germ-Free Mice
Authors: Li Yanze , Cao Wenming , Gao Na L , Zhao Xing-Ming , Chen Wei-Hua
Published: June 2021

Fecal microbiota transplantation (FMT) of human fecal samples into germ-free (GF) mice is useful for establishing causal relationships between the gut microbiota and human phenotypes. However, due to the intrinsic differences between human and mouse intestines and the different diets of the two organisms, it may not be possible to replicate human phenotypes in mice through FMT; similarly, treatments that are effective in mouse models may not be effective in humans. In this study, we aimed to identify human gut microbes that undergo significant and consistent changes (i.e., in relative abundances) after transplantation into GF mice in multiple experimental settings. We collected 16S rDNA-seq data from four published studies and analyzed the gut microbiota profiles from 1713 human–mouse pairs. Strikingly, on average, we found that only 47% of the human gut microbes could be re-established in mice at the species level, among which more than 1/3 underwent significant changes (referred to as “variable taxa”). Most of the human gut microbes that underwent significant changes were consistent across multiple human–mouse pairs and experimental settings. Consequently, about 1/3 of human samples changed their enterotypes, i.e., significant changes in their leading species after FMT. Mice fed with a controlled diet showed a lower enterotype change rate (23.5%) than those fed with a noncontrolled diet (49.0%), suggesting a possible solution for rescue. Most of the variable taxa have been reported to be implicated in human diseases, with some recognized as the causative species. Our results highlight the challenges of using a mouse model to replicate human gut microbiota-associated phenotypes, provide useful information for researchers using mice in gut microbiota studies, and call for additional validations after FMT. An online database named FMT-DB is publicly available at http://fmt2mice.humangut.info/#/.
Understanding Modern Nigeria
Authors: Falola Toyin
Published: June 2021

Since its independence from Britain in 1960, Nigeria has emerged as Africa's second largest economy and one of the biggest producers of oil in the world. Despite its economic success, however, there are deep divisions among its two hundred and fifty ethnic groups. Centered around three of the dominant themes of Nigeria's post-colonial narrative - ethnicity, democracy and governance, this is an accessible and comprehensive introduction to the history and events that have shaped these three areas. World-renowned expert in Nigerian history, Toyin Falola shows us how the British laid the foundations of modern Nigeria, with colonialism breading competition for resources and power and the widening cleavages between the Hausa-Fulani, Yoruba, and Igbo ethnic groups that had been forced together under British rule, the choice of federalism as a political system, and the religious and political pluralism that have shaped its institutions and practices. Using an examination of the outcomes of this history, manifested in hunger, violence, poverty, human rights violations, threats of secession and corruption, where power and resources are used to reproduce underdevelopment, Falola offers insights and recommendations for the future of policy and the potential for intervention in the country.
Returning Memories
Authors: Wienand Christiane
Published: June 2021

Millions of former German soldiers (known as Heimkehrer, literally "homecomers," or returnees) returned from captivity as prisoners of war at the end of the Second World War, an experience that had profound effects on German society and touched almost every German family. Based on extensive archival research and oral history interviews, this book provides the first comprehensive analysis ofthe history of the German returnees, explored as a history of memory, both during Germany's division and after unification. At its core lies the question of how the experiences of war captivity were transformed into individual and collective memories. The book argues that memory of the experience of captivity and return is complex and multilayered and has been shaped by postwar political and social frameworks. Christiane Wienand is a Research Fellow on the AHRC-funded research project "Reverberations of War: Communities of Experience and Identification in Germany and Europe since 1945." She holds a PhD in History from University College London.
Rossini and Post-Napoleonic Europe
Authors: Roberts Warren
Published: June 2021

This book examines Rossini within the context of his own time, one of Napoleonic domination of Italy, restoration of the Bourbon monarchy in Naples in 1815, and the 1830 Revolution in Paris. Using thetechniques of the historian, and reading librettos as texts, the author analyzes the five operas treated in detail in the book (Il barbiere di Siviglia, Cenerentola, La gazza ladra, Matilde di Shabran, and Il viaggio a Reims) as responses, each in its own way, to the history that the composer experienced. Roberts shows that Rossini made probing commentaries on politics and religion in a time of reaction and revolution, and that the composer was well-informed on post-Napoleonic politics. Rossini's comic writing served very serious purposes, exposing the problems and complications of an age that he observed with striking clarity. Warren Roberts is Professor Emeritus of History at the University at Albany, SUNY, and has published extensively on eighteenth-century French culture.
Performative Analysis
Authors: Swinkin Jeffrey
Published: June 2021

This book proposes a new model for understanding the musical work, which includes interpretation -- both analysis- and performance-based -- as an integral component.
Iron status of full-term infants in early infancy is not associated with maternal ferritin levels nor infant feeding practice
Authors: Chan Kate C. , Tsun Joseph G. S. , Li Albert M. , Tam Wing Hung
Published: June 2021

Iron deficiency (ID) in early life is associated with morbidities. Most fetal iron required for infant growth is acquired in the third trimester from maternal iron store. However, how prenatal iron level affects ferritin level in early infancy remains controversial. This study aimed to examine the associations between maternal ferritin levels and cord blood serum ferritin (CBSF) and to compare the ferritin levels between different feeding practices in early infancy. Healthy Chinese mothers with uncomplicated pregnancy and their infants were followed up at 3 months post-delivery for questionnaire completion and infant blood collection. Infants who were predominantly breastfed and those who were predominantly formula fed were included in this analysis. Serum ferritin levels were measured in maternal blood samples collected upon delivery, cord blood and infant blood samples at 3 months of age. Ninety-seven mother–baby dyads were included. Maternal ID is common (56 %) while the CBSF levels were significantly higher than maternal ferritin levels. Only three infants (3 %) had ID at 3 months of age. There were no significant correlations between maternal ferritin levels with CBSF (r 0·168, P = 0·108) nor with infant ferritin levels at 3 months of age (r 0·023, P = 0·828). Infant ferritin levels at 3 months were significantly and independently associated with CBSF (P = 0·007) and birth weight (P < 0·001) after adjusting for maternal age, parity, maternal education, infant sex and feeding practice. In conclusion, maternal ID was common upon delivery. However, maternal ferritin levels were not significantly associated with CBSF concentrations nor infant ferritin concentrations at 3 months of age.
Crude Calculations: Productivity and the Profitability of Conquest
Authors: Coe Andrew J. , Markowitz Jonathan N.
Published: June 2021

For many centuries, conquest was commonplace, and its attractiveness was central to the character of international politics. Why has it declined? Existing theories cannot explain why powerful countries no longer conquer states with easily extractable wealth. We develop an explanation based on the relationship between a potential conqueror's economic productivity and its ability to profit from conquest. Productivity has opposing effects on conquest's profitability: it raises the opportunity cost of each asset diverted to conquest, but also reduces the quantity of assets required for conquest. The net effect is determined by the composition of investment in innovation. We document that since at least 1950 investment has been predominantly aimed at civilian, not military innovations, so that rising productivity should reduce conquest's net profitability. Using cost analyses of comparable wars, we estimate bounds on the profitability of conquering the oil and gas reserves of the Persian Gulf, a very tempting target, for the United States and Iraq, two potential conquerors of widely differing productivity. Though both mechanisms operate, we find that the net effect of higher productivity is to reduce the profits from conquest. Moreover, this net effect is large enough to render conquest generally unprofitable for contemporary high-productivity states.
Communication-free autonomous cooperative circumnavigation of unpredictable dynamic objects
Authors: Matveev A. S. , Magerkin V. V.
Published: June 2021

Each of several speed-limited planar robots is driven by the acceleration, limited in magnitude. There is an unpredictable dynamic complex object, for example, a group of moving targets or an extended moving and deforming body. The robots should reach and then repeatedly trace a certain object-dependent moving and deforming curve that encircles the object and also achieve an effective self-deployment over it. This may be, for example, the locus of points at a desired mean distance or distance from a group of targets or a single extended object, respectively. Every robot has access to the nearest point of the curve and its own velocity and “sees” the objects within a finite sensing range. The robots have no communication facilities, cannot differentiate the peers, and are to be driven by a common law. Necessary conditions for the solvability of the mission are established. Under their slight and partly unavoidable enhancement, a new decentralized control strategy is proposed and shown to solve the mission, while excluding inter-robot collisions, and for the case of a steady curve, to evenly distribute the robots over the curve and to ensure a prespecified speed of their motion over it. These are justified via rigorous global convergence results and confirmed via computer simulations.
An Analytical Model for Lateral Erosion From Saltating Bedload Particle Impacts
Authors: Li Tingan , Venditti Jeremy G. , Sklar Leonard S.
Published: June 2021

The width of bedrock rivers is set by the competition between vertical and lateral erosion in uplifting landscapes. Compared with vertical erosion rates, less is known about the lateral erosion rates that are thought to dominate when river beds are alluviated. Here, we derive an analytical model for lateral erosion by saltating bedload particle impacts that are deflected by alluvial cover. The analytical model is a simplification of the Li et al. (2020, https://doi.org/10.1029/2019jf005509) numerical model of the same process. The analytical model predicts a nonlinear dependence of lateral erosion rate on sediment supply, shear stress, and grain size, revealing the same behavior observed in the numerical model, but without tracking particle movements through time and space. The analytical model considers both uniformly distributed cover and patchy partial cover that are implemented with a fully alluviated patch along one bank and bare bedrock along the other. The model predicts that lateral erosion rate peaks when the bed is ∼70% covered for uniformly distributed alluvium, or when the bed is fully covered for patchy alluvium. Vertical erosion dominates over lateral erosion for ∼75% and >90% of sediment supply and transport stage conditions for uniformly distributed cover and patchy cover, respectively. We use the model to derive a phase diagram of channel responses (steepening, flattening, narrowing, and widening) for various combinations of transport stage and relative sediment supply. Application of our model to Boulder Creek, CA, captures the observed channel widening in response to increased sediment supply and steepening in response to larger grain size.
Characterization of Municipal Water Uses in the Contiguous United States
Authors: Chinnasamy Cibi Vishnu , Arabi Mazdak , Sharvelle Sybil , Warziniack Travis , Furth Canon D. , Dozier Andre
Published: June 2021

This study investigates municipal water use patterns across the Contiguous United States (CONUS). The objectives of this study are to explore temporal trends in water use, improve characterization of indoor and outdoor uses, and improve characterization of commercial, industrial, and institutional (CII) water use in cities across the CONUS. A comprehensive survey was conducted to compile monthly water use data from 126 municipalities for the period 2005–2017 with specific information about residential and CII water use categories. Changes in liters per capita per day and the CII to Residential water use ratio were related to climatic, urban‐geologic and socio‐economic variables. Results indicate an overall decreasing trend in municipal water uses with higher reductions achieved in residential sector. Both residential and CII water use exhibit high seasonality over an average year. The CII to Residential ratio increases with city population and is highest in cities in the Northeast Census region. Cities in South and West Census regions have high municipal water uses and highest reductions in annual per capita‐day water use. Cities in arid climate regions have the highest water uses, compared to other cities, due to landscape irrigation. April precipitation, annual vapor pressure deficit, number of employees in the manufacturing (or, other services except public administration) sector, total percentage of houses built before 1950 and total percentage of single‐family houses explain much of the variation in CII to Residential water use ratio across the CONUS. This study guides improved characterization of municipal water uses and water demand management strategies.
Shock‐Induced Incongruent Melting of Olivine in Kamargaon L6 Chondrite
Authors: Tiwari Kishan , Ghosh Sujoy , Miyahara Masaaki , Ray Dwijesh
Published: June 2021

In this study, we report for the first‐time shock‐induced incongruent melting of olivine in an ordinary chondrite. Several olivine grains (Fo74), entrained in the shock‐melt vein of the Kamargaon L6 chondrite, were dissociated into magnesiowüstite (XFe = 0.71) and orthoenstatite (XFe = 0.22). We propose that the breakdown of olivine took place as a result of incongruent melting to produce magnesiowüstite and Mg‐rich liquid. We suggest that bridgmanite may have crystallized as the second phase from the olivine melt which back‐transformed to a low‐pressure phase of orthoenstatite from subsequent high‐temperature and low‐pressure events. In this case, olivine grains may have experienced pressure and temperature of ∼25 GPa and ∼2500°C, respectively. Our results suggest that the incongruent melting of olivine may possibly operate as one of the alternative mechanisms of dissociation reaction driving the phase transformation of olivine in the natural systems.
Biomass Burning is an Important Source of Organic Aerosols in Interior Alaska
Authors: Haque Md. Mozammel , Kawamura Kimitaka , Deshmukh Dhananjay K. , Kunwar Bhagawati , Kim Yongwon
Published: June 2021

Biomass burning (BB) affects air quality, the global cycling of carbon, climate, and human health. Intensive BB activities occur throughout the year due to wildfires and domestic wood burning in Fairbanks. We collected total suspended particle samples from the air in Fairbanks from June 2008 to June 2009. Here, we report seasonal variations in the molecular composition of organic aerosols and its BB contributions in Fairbanks. Levoglucosan is the dominant BB tracer (annual mean 67 ± 77 ng m−3), showing a winter maximum (145 ± 47 ng m−3) and spring minimum (12 ± 12 ng m−3). Levoglucosan showed significant correlations (p < 0.001) with organic carbon (OC), water‐soluble organic carbon (WSOC), and PM2.5, indicating a significant contribution of BB to hazes in Fairbanks. However, no correlation exists between levoglucosan and non‐sea salt potassium (nss‐K+), which has been proposed as a BB tracer. We hypothesize that nss‐K+ is removed by deposition on the inner surfaces of woodstove chimneys. Levoglucosan contributes 3.6% to OC and 6.3% to WSOC in winter, indicating that BB significantly affects carbonaceous aerosols in central Alaska. Moreover, positive matrix factorization analysis demonstrates that BB is an important source (47.5%) of Fairbanks year‐round aerosols. We conclude that domestic wood burning is an important source of atmospheric particles that impact the air quality of Fairbanks, especially in winter. We presumed that Fairbanks BB products might be transported to the remote Arctic, potentially affecting the chemical composition of Arctic aerosols. These findings will be useful to better understand the seasonal influence of BB on the Arctic and subarctic aerosols.
The clinical use of blood-test factors for Alzheimer’s disease: improving the prediction of cerebral amyloid deposition by the QPLEXTM Alz plus assay kit
Authors: Kim Haeng Jun , Park Jong-Chan , Jung Keum Sim , Kim Jiyeong , Jang Ji Sung , Kwon Sunghoon , Byun Min Soo , Yi Dahyun , Byeon Gihwan , Jung Gijung , Kim Yu Kyeong , Lee Dong Young , Han Sun-Ho , Mook-Jung Inhee
Published: June 2021

Alzheimer’s disease (AD) is the leading cause of dementia, and many studies have focused on finding effective blood biomarkers for the accurate diagnosis of this disease. Predicting cerebral amyloid deposition is considered the key for AD diagnosis because a cerebral amyloid deposition is the hallmark of AD pathogenesis. Previously, blood biomarkers were discovered to predict cerebral amyloid deposition, and further efforts have been made to increase their sensitivity and specificity. In this study, we analyzed blood-test factors (BTFs) that can be commonly measured in medical health check-ups from 149 participants with cognitively normal, 87 patients with mild cognitive impairment, and 64 patients with clinically diagnosed AD dementia with brain amyloid imaging data available. We demonstrated that four factors among regular health check-up blood tests, cortisol, triglyceride/high-density lipoprotein cholesterol ratio, alanine aminotransferase, and free triiodothyronine, showed either a significant difference by or correlation with cerebral amyloid deposition. Furthermore, we made a prediction model for Pittsburgh compound B-positron emission tomography positivity, using BTFs and the previously discovered blood biomarkers, the QPLEXTMAlz plus assay kit biomarker panel, and the area under the curve was significantly increased up to 0.845% with 69.4% sensitivity and 90.6% specificity. These results show that BTFs could be used as co-biomarkers and that a highly advanced prediction model for amyloid plaque deposition could be achieved by the combinational use of diverse biomarkers.
Divergence of a genomic island leads to the evolution of melanization in a halophyte root fungus
Authors: Yuan Zhilin , Druzhinina Irina S , Gibbons John G , Zhong Zhenhui , Van de Peer Yves , Rodriguez Russell J , Liu Zhongjian , Wang Xinyu , Wei Huanshen , Wu Qi , Wang Jieyu , Shi Guohui , Cai Feng , Peng Long , Martin Francis M
Published: June 2021

Understanding how organisms adapt to extreme living conditions is central to evolutionary biology. Dark septate endophytes (DSEs) constitute an important component of the root mycobiome and they are often able to alleviate host abiotic stresses. Here, we investigated the molecular mechanisms underlying the beneficial association between the DSE Laburnicola rhizohalophila and its host, the native halophyte Suaeda salsa, using population genomics. Based on genome-wide Fst (pairwise fixation index) and Vst analyses, which compared the variance in allele frequencies of single-nucleotide polymorphisms (SNPs) and copy number variants (CNVs), respectively, we found a high level of genetic differentiation between two populations. CNV patterns revealed population-specific expansions and contractions. Interestingly, we identified a ~20 kbp genomic island of high divergence with a strong sign of positive selection. This region contains a melanin-biosynthetic polyketide synthase gene cluster linked to six additional genes likely involved in biosynthesis, membrane trafficking, regulation, and localization of melanin. Differences in growth yield and melanin biosynthesis between the two populations grown under 2% NaCl stress suggested that this genomic island contributes to the observed differences in melanin accumulation. Our findings provide a better understanding of the genetic and evolutionary mechanisms underlying the adaptation to saline conditions of the L. rhizohalophila–S. salsa symbiosis.
R2DT is a framework for predicting and visualising RNA secondary structure using templates
Authors: Sweeney Blake A. , Hoksza David , Nawrocki Eric P. , Ribas Carlos Eduardo , Madeira Fábio , Cannone Jamie J. , Gutell Robin , Maddala Aparna , Meade Caeden D. , Williams Loren Dean , Petrov Anton S. , Chan Patricia P. , Lowe Todd M. , Finn Robert D. , Petrov Anton I.
Published: June 2021

Non-coding RNAs (ncRNA) are essential for all life, and their functions often depend on their secondary (2D) and tertiary structure. Despite the abundance of software for the visualisation of ncRNAs, few automatically generate consistent and recognisable 2D layouts, which makes it challenging for users to construct, compare and analyse structures. Here, we present R2DT, a method for predicting and visualising a wide range of RNA structures in standardised layouts. R2DT is based on a library of 3,647 templates representing the majority of known structured RNAs. R2DT has been applied to ncRNA sequences from the RNAcentral database and produced >13 million diagrams, creating the world’s largest RNA 2D structure dataset. The software is amenable to community expansion, and is freely available at https://github.com/rnacentral/R2DT and a web server is found at https://rnacentral.org/r2dt.
Structural insight on assembly-line catalysis in terpene biosynthesis
Authors: Faylo Jacque L. , van Eeuwen Trevor , Kim Hee Jong , Gorbea Colón Jose J. , Garcia Benjamin A. , Murakami Kenji , Christianson David W.
Published: June 2021

Fusicoccadiene synthase from Phomopsis amygdali (PaFS) is a unique bifunctional terpenoid synthase that catalyzes the first two steps in the biosynthesis of the diterpene glycoside Fusicoccin A, a mediator of 14-3-3 protein interactions. The prenyltransferase domain of PaFS generates geranylgeranyl diphosphate, which the cyclase domain then utilizes to generate fusicoccadiene, the tricyclic hydrocarbon skeleton of Fusicoccin A. Here, we use cryo-electron microscopy to show that the structure of full-length PaFS consists of a central octameric core of prenyltransferase domains, with the eight cyclase domains radiating outward via flexible linker segments in variable splayed-out positions. Cryo-electron microscopy and chemical crosslinking experiments additionally show that compact conformations can be achieved in which cyclase domains are more closely associated with the prenyltransferase core. This structural analysis provides a framework for understanding substrate channeling, since most of the geranylgeranyl diphosphate generated by the prenyltransferase domains remains on the enzyme for cyclization to form fusicoccadiene.
Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography
Authors: Liu Xiaoyang , Ronne Arthur , Yu Lin-Chieh , Liu Yang , Ge Mingyuan , Lin Cheng-Hung , Layne Bobby , Halstenberg Phillip , Maltsev Dmitry S. , Ivanov Alexander S. , Antonelli Stephen , Dai Sheng , Lee Wah-Keat , Mahurin Shannon M. , Frenkel Anatoly I. , Wishart James F. , Xiao Xianghui , Chen-Wiegart Yu-chen Karen
Published: June 2021

Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.
Manganese doping for enhanced magnetic brightening and circular polarization control of dark excitons in paramagnetic layered hybrid metal-halide perovskites
Authors: Neumann Timo , Feldmann Sascha , Moser Philipp , Delhomme Alex , Zerhoch Jonathan , van de Goor Tim , Wang Shuli , Dyksik Mateusz , Winkler Thomas , Finley Jonathan J. , Plochocka Paulina , Brandt Martin S. , Faugeras Clément , Stier Andreas V. , Deschler Felix
Published: June 2021

Materials combining semiconductor functionalities with spin control are desired for the advancement of quantum technologies. Here, we study the magneto-optical properties of novel paramagnetic Ruddlesden-Popper hybrid perovskites Mn:(PEA)2PbI4(PEA = phenethylammonium) and report magnetically brightened excitonic luminescence with strong circular polarization from the interaction with isolated Mn2+ions. Using a combination of superconducting quantum interference device (SQUID) magnetometry, magneto-absorption and transient optical spectroscopy, we find that a dark exciton population is brightened by state mixing with the bright excitons in the presence of a magnetic field. Unexpectedly, the circular polarization of the dark exciton luminescence follows the Brillouin-shaped magnetization with a saturation polarization of 13% at 4 K and 6 T. From high-field transient magneto-luminescence we attribute our observations to spin-dependent exciton dynamics at early times after excitation, with first indications for a Mn-mediated spin-flip process. Our findings demonstrate manganese doping as a powerful approach to control excitonic spin physics in Ruddlesden-Popper perovskites, which will stimulate research on this highly tuneable material platform with promise for tailored interactions between magnetic moments and excitonic states.
Multication perovskite 2D/3D interfaces form via progressive dimensional reduction
Authors: Proppe Andrew H. , Johnston Andrew , Teale Sam , Mahata Arup , Quintero-Bermudez Rafael , Jung Eui Hyuk , Grater Luke , Cui Teng , Filleter Tobin , Kim Chang-Yong , Kelley Shana O. , De Angelis Filippo , Sargent Edward H.
Published: June 2021

Many of the best-performing perovskite photovoltaic devices make use of 2D/3D interfaces, which improve efficiency and stability – but it remains unclear how the conversion of 3D-to-2D perovskite occurs and how these interfaces are assembled. Here, we use in situ Grazing-Incidence Wide-Angle X-Ray Scattering to resolve 2D/3D interface formation during spin-coating. We observe progressive dimensional reduction from 3D to n = 3 → 2 → 1 when we expose (MAPbBr3)0.05(FAPbI3)0.95 perovskites to vinylbenzylammonium ligand cations. Density functional theory simulations suggest ligands incorporate sequentially into the 3D lattice, driven by phenyl ring stacking, progressively bisecting the 3D perovskite into lower-dimensional fragments to form stable interfaces. Slowing the 2D/3D transformation with higher concentrations of antisolvent yields thinner 2D layers formed conformally onto 3D grains, improving carrier extraction and device efficiency (20% 3D-only, 22% 2D/3D). Controlling this progressive dimensional reduction has potential to further improve the performance of 2D/3D perovskite photovoltaics.
Exposing the hidden influence of selection rules on phonon–phonon scattering by pressure and temperature tuning
Authors: Ravichandran Navaneetha K. , Broido David
Published: June 2021

Selection rules act to restrict the intrinsic anharmonic interactions between phonons in all crystals. Yet their influence on phonon propagation is hidden in most materials and so, hard to interrogate experimentally. Using ab initio calculations, we show that the otherwise invisible impact of selection rules on three-phonon scattering can be exposed through anomalous signatures in the pressure (P) and temperature (T) dependence of the thermal conductivities, κ, of certain compounds. Boron phosphide reveals such underlying behavior through an exceptionally sharp initial rise in κ with increasing P, which may be the steepest of any material, and also a peak and decrease in κ at high P. These features are in stark contrast to the measured behavior for many solids, and they occur at experimentally accessible conditions. These findings give a deep understanding of phonon lifetimes and heat conduction in solids, and motivate experimental efforts to observe the predicted behavior.
Clinical and molecular characteristics of COVID-19 patients with persistent SARS-CoV-2 infection
Authors: Yang Bin , Fan Junpeng , Huang Jia , Guo Ensong , Fu Yu , Liu Si , Xiao Rourou , Liu Chen , Lu Funian , Qin Tianyu , He Chao , Wang Zizhuo , Qin Xu , Hu Dianxing , You Lixin , Li Xi , Wang Tian , Wu Peng , Chen Gang , Zhou Jianfeng , Li Kezhen , Sun Chaoyang
Published: June 2021

The characteristics of COVID-19 patients with persistent SARS-CoV-2 infection are not yet well described. Here, we compare the clinical and molecular features of patients with long duration of viral shedding (LDs) with those from patients with short duration patients (SDs), and healthy donors (HDs). We find that several cytokines and chemokines, such as interleukin (IL)-2, tumor necrosis factor (TNF) and lymphotoxin α (LT-α) are present at lower levels in LDs than SDs. Single-cell RNA sequencing shows that natural killer (NK) cells and CD14+ monocytes are reduced, while regulatory T cells are increased in LDs; moreover, T and NK cells in LDs are less activated than in SDs. Importantly, most cells in LDs show reduced expression of ribosomal protein (RP) genes and related pathways, with this inversed correlation between RP levels and infection duration further validated in 103 independent patients. Our results thus indicate that immunosuppression and low RP expression may be related to the persistence of the viral infection in COVID-19 patients.
Dislocation interactions in olivine control postseismic creep of the upper mantle
Authors: Wallis David , Hansen Lars N. , Wilkinson Angus J. , Lebensohn Ricardo A.
Published: June 2021

Changes in stress applied to mantle rocks, such as those imposed by earthquakes, commonly induce a period of transient creep, which is often modelled based on stress transfer among slip systems due to grain interactions. However, recent experiments have demonstrated that the accumulation of stresses among dislocations is the dominant cause of strain hardening in olivine at temperatures ≤600 °C, raising the question of whether the same process contributes to transient creep at higher temperatures. Here, we demonstrate that olivine samples deformed at 25 °C or 1150–1250 °C both preserve stress heterogeneities of ~1 GPa that are imparted by dislocations and have correlation lengths of ~1 μm. The similar stress distributions formed at these different temperatures indicate that accumulation of stresses among dislocations also provides a contribution to transient creep at high temperatures. The results motivate a new generation of models that capture these intragranular processes and may refine predictions of evolving mantle viscosity over the earthquake cycle.
Site-specific ubiquitylation acts as a regulator of linker histone H1
Authors: Höllmüller Eva , Geigges Simon , Niedermeier Marie L. , Kammer Kai-Michael , Kienle Simon M. , Rösner Daniel , Scheffner Martin , Marx Andreas , Stengel Florian
Published: June 2021

Decoding the role of histone posttranslational modifications (PTMs) is key to understand the fundamental process of epigenetic regulation. This is well studied for PTMs of core histones but not for linker histone H1 in general and its ubiquitylation in particular due to a lack of proper tools. Here, we report on the chemical synthesis of site-specifically mono-ubiquitylated H1.2 and identify its ubiquitin-dependent interactome on a proteome-wide scale. We show that site-specific ubiquitylation of H1 at position K64 modulates interactions with deubiquitylating enzymes and the deacetylase SIRT1. Moreover, it affects H1-dependent chromatosome assembly and phase separation resulting in a more open chromatosome conformation generally associated with a transcriptionally active chromatin state. In summary, we propose that site-specific ubiquitylation plays a general regulatory role for linker histone H1.
Probing the biogenesis pathway and dynamics of thylakoid membranes
Authors: Huokko Tuomas , Ni Tao , Dykes Gregory F. , Simpson Deborah M. , Brownridge Philip , Conradi Fabian D. , Beynon Robert J. , Nixon Peter J. , Mullineaux Conrad W. , Zhang Peijun , Liu Lu-Ning
Published: June 2021

How thylakoid membranes are generated to form a metabolically active membrane network and how thylakoid membranes orchestrate the insertion and localization of protein complexes for efficient electron flux remain elusive. Here, we develop a method to modulate thylakoid biogenesis in the rod-shaped cyanobacterium Synechococcus elongatus PCC 7942 by modulating light intensity during cell growth, and probe the spatial-temporal stepwise biogenesis process of thylakoid membranes in cells. Our results reveal that the plasma membrane and regularly arranged concentric thylakoid layers have no physical connections. The newly synthesized thylakoid membrane fragments emerge between the plasma membrane and pre-existing thylakoids. Photosystem I monomers appear in the thylakoid membranes earlier than other mature photosystem assemblies, followed by generation of Photosystem I trimers and Photosystem II complexes. Redistribution of photosynthetic complexes during thylakoid biogenesis ensures establishment of the spatial organization of the functional thylakoid network. This study provides insights into the dynamic biogenesis process and maturation of the functional photosynthetic machinery.
Brain network dynamics during working memory are modulated by dopamine and diminished in schizophrenia
Authors: Braun Urs , Harneit Anais , Pergola Giulio , Menara Tommaso , Schäfer Axel , Betzel Richard F. , Zang Zhenxiang , Schweiger Janina I. , Zhang Xiaolong , Schwarz Kristina , Chen Junfang , Blasi Giuseppe , Bertolino Alessandro , Durstewitz Daniel , Pasqualetti Fabio , Schwarz Emanuel , Meyer-Lindenberg Andreas , Bassett Danielle S. , Tost Heike
Published: June 2021

Dynamical brain state transitions are critical for flexible working memory but the network mechanisms are incompletely understood. Here, we show that working memory performance entails brain-wide switching between activity states using a combination of functional magnetic resonance imaging in healthy controls and individuals with schizophrenia, pharmacological fMRI, genetic analyses and network control theory. The stability of states relates to dopamine D1 receptor gene expression while state transitions are influenced by D2 receptor expression and pharmacological modulation. Individuals with schizophrenia show altered network control properties, including a more diverse energy landscape and decreased stability of working memory representations. Our results demonstrate the relevance of dopamine signaling for the steering of whole-brain network dynamics during working memory and link these processes to schizophrenia pathophysiology.
Cellular and physiological circadian mechanisms drive diurnal cell proliferation and expansion of white adipose tissue
Authors: Ribas-Latre Aleix , Santos Rafael Bravo , Fekry Baharan , Tamim Yomna M. , Shivshankar Samay , Mohamed Alaa M. T. , Baumgartner Corrine , Kwok Christopher , Gebhardt Claudia , Rivera Angielyn , Gao Zhanguo , Sun Kai , Heiker John T. , Snyder Brad E. , Kolonin Mikhail G. , Eckel-Mahan Kristin L.
Published: June 2021

Hyperplastic expansion of white adipose tissue (WAT) relies in part on the proliferation of adipocyte precursor cells residing in the stromal vascular cell fraction (SVF) of WAT. This study reveals a circadian clock- and feeding-induced diurnal pattern of cell proliferation in the SVF of visceral and subcutaneous WAT in vivo, with higher proliferation of visceral adipocyte progenitor cells subsequent to feeding in lean mice. Fasting or loss of rhythmic feeding eliminates this diurnal proliferation, while high fat feeding or genetic disruption of the molecular circadian clock modifies the temporal expression of proliferation genes and impinges on diurnal SVF proliferation in eWAT. Surprisingly, high fat diet reversal, sufficient to reverse elevated SVF proliferation in eWAT, was insufficient in restoring diurnal patterns of SVF proliferation, suggesting that high fat diet induces a sustained disruption of the adipose circadian clock. In conclusion, the circadian clock and feeding simultaneously impart dynamic, regulatory control of adipocyte progenitor proliferation, which may be a critical determinant of adipose tissue expansion and health over time.
Structural basis for inhibition of the AAA-ATPase Drg1 by diazaborine
Authors: Prattes Michael , Grishkovskaya Irina , Hodirnau Victor-Valentin , Rössler Ingrid , Klein Isabella , Hetzmannseder Christina , Zisser Gertrude , Gruber Christian C. , Gruber Karl , Haselbach David , Bergler Helmut
Published: June 2021

The hexameric AAA-ATPase Drg1 is a key factor in eukaryotic ribosome biogenesis and initiates cytoplasmic maturation of the large ribosomal subunit by releasing the shuttling maturation factor Rlp24. Drg1 monomers contain two AAA-domains (D1 and D2) that act in a concerted manner. Rlp24 release is inhibited by the drug diazaborine which blocks ATP hydrolysis in D2. The mode of inhibition was unknown. Here we show the first cryo-EM structure of Drg1 revealing the inhibitory mechanism. Diazaborine forms a covalent bond to the 2′-OH of the nucleotide in D2, explaining its specificity for this site. As a consequence, the D2 domain is locked in a rigid, inactive state, stalling the whole Drg1 hexamer. Resistance mechanisms identified include abolished drug binding and altered positioning of the nucleotide. Our results suggest nucleotide-modifying compounds as potential novel inhibitors for AAA-ATPases.
Mechanistic insights into the R-loop formation and cleavage in CRISPR-Cas12i1
Authors: Zhang Bo , Luo Diyin , Li Yu , Perčulija Vanja , Chen Jing , Lin Jinying , Ye Yangmiao , Ouyang Songying
Published: June 2021

Cas12i is a newly identified member of the functionally diverse type V CRISPR-Cas effectors. Although Cas12i has the potential to serve as genome-editing tool, its structural and functional characteristics need to be investigated in more detail before effective application. Here we report the crystal structures of the Cas12i1 R-loop complexes before and after target DNA cleavage to elucidate the mechanisms underlying target DNA duplex unwinding, R-loop formation and cis cleavage. The structure of the R-loop complex after target DNA cleavage also provides information regarding trans cleavage. Besides, we report a crystal structure of the Cas12i1 binary complex interacting with a pseudo target oligonucleotide, which mimics target interrogation. Upon target DNA duplex binding, the Cas12i1 PAM-interacting cleft undergoes a remarkable open-to-closed adjustment. Notably, a zipper motif in the Helical-I domain facilitates unzipping of the target DNA duplex. Formation of the 19-bp crRNA-target DNA strand heteroduplex in the R-loop complexes triggers a conformational rearrangement and unleashes the DNase activity. This study provides valuable insights for developing Cas12i1 into a reliable genome-editing tool.