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Science Advances

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https://www.readbyqxmd.com/read/28275738/long-range-allosteric-signaling-in-red-light-regulated-diguanylyl-cyclases
#1
Geoffrey Gourinchas, Stefan Etzl, Christoph Göbl, Uršula Vide, Tobias Madl, Andreas Winkler
Nature has evolved an astonishingly modular architecture of covalently linked protein domains with diverse functionalities to enable complex cellular networks that are critical for cell survival. The coupling of sensory modules with enzymatic effectors allows direct allosteric regulation of cellular signaling molecules in response to diverse stimuli. We present molecular details of red light-sensing bacteriophytochromes linked to cyclic dimeric guanosine monophosphate-producing diguanylyl cyclases. Elucidation of the first crystal structure of a full-length phytochrome with its enzymatic effector, in combination with the characterization of light-induced changes in conformational dynamics, reveals how allosteric light regulation is fine-tuned by the architecture and composition of the coiled-coil sensor-effector linker and also the central helical spine...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275737/programmable-and-coherent-crystallization-of-semiconductors
#2
Liyang Yu, Muhammad R Niazi, Guy O Ngongang Ndjawa, Ruipeng Li, Ahmad R Kirmani, Rahim Munir, Ahmed H Balawi, Frédéric Laquai, Aram Amassian
The functional properties and technological utility of polycrystalline materials are largely determined by the structure, geometry, and spatial distribution of their multitude of crystals. However, crystallization is seeded through stochastic and incoherent nucleation events, limiting the ability to control or pattern the microstructure, texture, and functional properties of polycrystalline materials. We present a universal approach that can program the microstructure of materials through the coherent seeding of otherwise stochastic homogeneous nucleation events...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275736/sequential-self-folding-of-polymer-sheets
#3
Ying Liu, Brandi Shaw, Michael D Dickey, Jan Genzer
Shape plays an important role in defining the function of materials, particularly those found in nature. Several strategies exist to program materials to change from one shape to another; however, few can temporally and spatially control the shape. Programming the sequence of shape transformation with temporal control has been driven by the desire to generate complex shapes with high yield and to create multiple shapes from the same starting material. This paper demonstrates a markedly simple strategy for programmed self-folding of two-dimensional (2D) polymer sheets into 3D objects in a sequential manner using external light...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275735/controlling-liquid-splash-on-superhydrophobic-surfaces-by-a-vesicle-surfactant
#4
Meirong Song, Jie Ju, Siqi Luo, Yuchun Han, Zhichao Dong, Yilin Wang, Zhen Gu, Lingjuan Zhang, Ruiran Hao, Lei Jiang
Deposition of liquid droplets on solid surfaces is of great importance to many fundamental scientific principles and technological applications, such as spraying, coating, and printing. For example, during the process of pesticide spraying, more than 50% of agrochemicals are lost because of the undesired bouncing and splashing behaviors on hydrophobic or superhydrophobic leaves. We show that this kind of splashing on superhydrophobic surfaces can be greatly inhibited by adding a small amount of a vesicular surfactant, Aerosol OT...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275734/decoupling-biogeochemical-records-extinction-and-environmental-change-during-the-cambrian-spice-event
#5
James D Schiffbauer, John Warren Huntley, David A Fike, Matthew Jarrell Jeffrey, Jay M Gregg, Kevin L Shelton
Several positive carbon isotope excursions in Lower Paleozoic rocks, including the prominent Upper Cambrian Steptoean Positive Carbon Isotope Excursion (SPICE), are thought to reflect intermittent perturbations in the hydrosphere-biosphere system. Models explaining these secular changes are abundant, but the synchronicity and regional variation of the isotope signals are not well understood. Examination of cores across a paleodepth gradient in the Upper Cambrian central Missouri intrashelf basin (United States) reveals a time-transgressive, facies-dependent nature of the SPICE...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275733/three-dimensional-microarchitected-materials-and-devices-using-nanoparticle-assembly-by-pointwise-spatial-printing
#6
Mohammad Sadeq Saleh, Chunshan Hu, Rahul Panat
Three-dimensional (3D) hierarchical materials are important to a wide range of emerging technological applications. We report a method to synthesize complex 3D microengineered materials, such as microlattices, with nearly fully dense truss elements with a minimum diameter of approximately 20 μm and having high aspect ratios (up to 20:1) without using any templating or supporting materials. By varying the postprocessing conditions, we have also introduced an additional control over the internal porosity of the truss elements to demonstrate a hierarchical porous structure with an overall void size and feature size control of over five orders of magnitudes in length scale...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275732/a-three-degree-horizon-of-peace-in-the-military-alliance-network
#7
Weihua Li, Aisha E Bradshaw, Caitlin B Clary, Skyler J Cranmer
States form defensive military alliances to enhance their security in the face of potential or realized interstate conflict. The network of these international alliances is increasingly interconnected, now linking most of the states in a complex web of ties. These alliances can be used both as a tool for securing cooperation and to foster peace between direct partners. However, do indirect connections-such as the ally of an ally or even further out in the alliance network-result in lower probabilities of conflict? We investigate the extent to which military alliances produce peace between states that are not directly allied...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275731/air-pollution-aerosol-interactions-produce-more-bioavailable-iron-for-ocean-ecosystems
#8
Weijun Li, Liang Xu, Xiaohuan Liu, Jianchao Zhang, Yangting Lin, Xiaohong Yao, Huiwang Gao, Daizhou Zhang, Jianmin Chen, Wenxing Wang, Roy M Harrison, Xiaoye Zhang, Longyi Shao, Pingqing Fu, Athanasios Nenes, Zongbo Shi
It has long been hypothesized that acids formed from anthropogenic pollutants and natural emissions dissolve iron (Fe) in airborne particles, enhancing the supply of bioavailable Fe to the oceans. However, field observations have yet to provide indisputable evidence to confirm this hypothesis. Single-particle chemical analysis for hundreds of individual atmospheric particles collected over the East China Sea shows that Fe-rich particles from coal combustion and steel industries were coated with thick layers of sulfate after 1 to 2 days of atmospheric residence...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275730/predatory-fish-depletion-and-recovery-potential-on-caribbean-reefs
#9
Abel Valdivia, Courtney Ellen Cox, John Francis Bruno
The natural, prehuman abundance of most large predators is unknown because of the lack of historical data and a limited understanding of the natural factors that control their populations. Determining the supportable predator biomass at a given location (that is, the predator carrying capacity) would help managers to optimize protection and would provide site-specific recovery goals. We assess the relationship between predatory reef fish biomass and several anthropogenic and environmental variables at 39 reefs across the Caribbean to (i) estimate their roles determining local predator biomass and (ii) determine site-specific recovery potential if fishing was eliminated...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275729/radar-interferometry-offers-new-insights-into-threats-to-the-angkor-site
#10
Fulong Chen, Huadong Guo, Peifeng Ma, Hui Lin, Cheng Wang, Natarajan Ishwaran, Peou Hang
The conservation of World Heritage is critical to the cultural and social sustainability of regions and nations. Risk monitoring and preventive diagnosis of threats to heritage sites in any given ecosystem are a complex and challenging task. Taking advantage of the performance of Earth Observation technologies, we measured the impacts of hitherto imperceptible and poorly understood factors of groundwater and temperature variations on the monuments in the Angkor World Heritage site (400 km(2)). We developed a two-scale synthetic aperture radar interferometry (InSAR) approach...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275728/assembly-of-mesoscale-helices-with-near-unity-enantiomeric-excess-and-light-matter-interactions-for-chiral-semiconductors
#11
Wenchun Feng, Ji-Young Kim, Xinzhi Wang, Heather A Calcaterra, Zhibei Qu, Louisa Meshi, Nicholas A Kotov
Semiconductors with chiral geometries at the nanoscale and mesoscale provide a rich materials platform for polarization optics, photocatalysis, and biomimetics. Unlike metallic and organic optical materials, the relationship between the geometry of chiral semiconductors and their chiroptical properties remains, however, vague. Homochiral ensembles of semiconductor helices with defined geometries open the road to understanding complex relationships between geometrical parameters and chiroptical properties of semiconductor materials...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275727/extreme-warmth-and-heat-stressed-plankton-in-the-tropics-during-the-paleocene-eocene-thermal-maximum
#12
Joost Frieling, Holger Gebhardt, Matthew Huber, Olabisi A Adekeye, Samuel O Akande, Gert-Jan Reichart, Jack J Middelburg, Stefan Schouten, Appy Sluijs
Global ocean temperatures rapidly warmed by ~5°C during the Paleocene-Eocene Thermal Maximum (PETM; ~56 million years ago). Extratropical sea surface temperatures (SSTs) met or exceeded modern subtropical values. With these warm extratropical temperatures, climate models predict tropical SSTs >35°C-near upper physiological temperature limits for many organisms. However, few data are available to test these projected extreme tropical temperatures or their potential lethality. We identify the PETM in a shallow marine sedimentary section deposited in Nigeria...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275726/enhanced-pedot-adhesion-on-solid-substrates-with-electrografted-p-edot-nh2
#13
Liangqi Ouyang, Bin Wei, Chin-Chen Kuo, Sheevangi Pathak, Brendan Farrell, David C Martin
Conjugated polymers, such as poly(3,4-ethylene dioxythiophene) (PEDOT), have emerged as promising materials for interfacing biomedical devices with tissue because of their relatively soft mechanical properties, versatile organic chemistry, and inherent ability to conduct both ions and electrons. However, their limited adhesion to substrates is a concern for in vivo applications. We report an electrografting method to create covalently bonded PEDOT on solid substrates. An amine-functionalized EDOT derivative (2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methanamine (EDOT-NH2), was synthesized and then electrografted onto conducting substrates including platinum, iridium, and indium tin oxide...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28275725/electrostatic-cloaking-of-surface-structure-for-dynamic-wetting
#14
Satoshi Nita, Minh Do-Quang, Jiayu Wang, Yu-Chung Chen, Yuji Suzuki, Gustav Amberg, Junichiro Shiomi
Dynamic wetting problems are fundamental to understanding the interaction between liquids and solids. Even in a superficially simple experimental situation, such as a droplet spreading over a dry surface, the result may depend not only on the liquid properties but also strongly on the substrate-surface properties; even for macroscopically smooth surfaces, the microscopic geometrical roughness can be important. In addition, because surfaces may often be naturally charged or electric fields are used to manipulate fluids, electric effects are crucial components that influence wetting phenomena...
February 2017: Science Advances
https://www.readbyqxmd.com/read/28275724/mitochondrial-metabolic-regulation-by-grp78
#15
Manoj Prasad, Kevin J Pawlak, William E Burak, Elizabeth E Perry, Brendan Marshall, Randy M Whittal, Himangshu S Bose
Steroids, essential for mammalian survival, are initiated by cholesterol transport by steroidogenic acute regulatory protein (StAR). Appropriate protein folding is an essential requirement of activity. Endoplasmic reticulum (ER) chaperones assist in folding of cytoplasmic proteins, whereas mitochondrial chaperones fold only mitochondrial proteins. We show that glucose regulatory protein 78 (GRP78), a master ER chaperone, is also present at the mitochondria-associated ER membrane (MAM), where it folds StAR for delivery to the outer mitochondrial membrane...
February 2017: Science Advances
https://www.readbyqxmd.com/read/28275723/efficient-oxygen-reduction-catalysis-by-subnanometer-pt-alloy-nanowires
#16
Kezhu Jiang, Dandan Zhao, Shaojun Guo, Xu Zhang, Xing Zhu, Jun Guo, Gang Lu, Xiaoqing Huang
The common knowledge is that Pt and Pt alloy nanoparticles (NPs) less than 2 nm are not desirable for oxygen reduction reaction (ORR). However, whether the same trend is expected in Pt-based nanowires (NWs) and nanoplates remains questionable because there is no scalable approach to make such Pt nanostructures. We report a general approach for preparing subnanometer Pt alloy NWs with a diameter of only 4 to 5 atomic layer thickness, ranging from monometallic Pt NWs to bimetallic PtNi and PtCo NWs and to trimetallic PtNiCo NWs...
February 2017: Science Advances
https://www.readbyqxmd.com/read/28275722/differential-contribution-of-app-metabolites-to-early-cognitive-deficits-in-a-tgcrnd8-mouse-model-of-alzheimer-s-disease
#17
Valentine Hamm, Céline Héraud, Jean-Bastien Bott, Karine Herbeaux, Carole Strittmatter, Chantal Mathis, Romain Goutagny
Alzheimer's disease (AD) is a neurodegenerative pathology commonly characterized by a progressive and irreversible deterioration of cognitive functions, especially memory. Although the etiology of AD remains unknown, a consensus has emerged on the amyloid hypothesis, which posits that increased production of soluble amyloid β (Aβ) peptide induces neuronal network dysfunctions and cognitive deficits. However, the relative failures of Aβ-centric therapeutics suggest that the amyloid hypothesis is incomplete and/or that the treatments were given too late in the course of AD, when neuronal damages were already too extensive...
February 2017: Science Advances
https://www.readbyqxmd.com/read/28261663/zika-virus-causes-testicular-atrophy
#18
Ryuta Uraki, Jesse Hwang, Kellie Ann Jurado, Sarah Householder, Laura J Yockey, Andrew K Hastings, Robert J Homer, Akiko Iwasaki, Erol Fikrig
Zika virus (ZIKV) is an emerging mosquito-borne flavivirus that has recently been found to cause fetal infection and neonatal abnormalities, including microcephaly and neurological dysfunction. ZIKV persists in the semen months after the acute viremic phase in humans. To further understand the consequences of ZIKV persistence in males, we infected Ifnar1(-/-) mice via subcutaneous injection of a pathogenic but nonlethal ZIKV strain. ZIKV replication persists within the testes even after clearance from the blood, with interstitial, testosterone-producing Leydig cells supporting virus replication...
February 2017: Science Advances
https://www.readbyqxmd.com/read/28261662/self-assembly-of-electronically-abrupt-borophene-organic-lateral-heterostructures
#19
Xiaolong Liu, Zonghui Wei, Itamar Balla, Andrew J Mannix, Nathan P Guisinger, Erik Luijten, Mark C Hersam
Two-dimensional boron sheets (that is, borophene) have recently been realized experimentally and found to have promising electronic properties. Because electronic devices and systems require the integration of multiple materials with well-defined interfaces, it is of high interest to identify chemical methods for forming atomically abrupt heterostructures between borophene and electronically distinct materials. Toward this end, we demonstrate the self-assembly of lateral heterostructures between borophene and perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA)...
February 2017: Science Advances
https://www.readbyqxmd.com/read/28261661/evolutionary-population-history-of-early-paleoamerican-cranial-morphology
#20
Noreen von Cramon-Taubadel, André Strauss, Mark Hubbe
The nature and timing of the peopling of the Americas is a subject of intense debate. In particular, it is unclear whether high levels of between-group craniometric diversity in South America result from multiple migrations or from local diversification processes. Previous attempts to explain this diversity have largely focused on testing alternative dispersal or gene flow models, reaching conflicting or inconclusive results. Here, a novel analytical framework is applied to three-dimensional geometric morphometric data to partition the effects of population divergence from geographically mediated gene flow to understand the ancestry of the early South Americans in the context of global human history...
February 2017: Science Advances
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