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Science Advances

Zexi Liang, Donglei Fan
Highly efficient and widely applicable working mechanisms that allow nanomaterials and devices to respond to external stimuli with controlled mechanical motions could make far-reaching impact to reconfigurable, adaptive, and robotic nanodevices. We report an innovative mechanism that allows multifold reconfiguration of mechanical rotation of semiconductor nanoentities in electric ( E ) fields by visible light stimulation. When illuminated by light in the visible-to-infrared regime, the rotation speed of semiconductor Si nanowires in E -fields can instantly increase, decrease, and even reverse the orientation, depending on the intensity of the applied light and the AC E -field frequency...
September 2018: Science Advances
Joseph Falson, Daniela Tabrea, Ding Zhang, Inti Sodemann, Yusuke Kozuka, Atsushi Tsukazaki, Masashi Kawasaki, Klaus von Klitzing, Jurgen H Smet
Half-filled Landau levels host an emergent Fermi liquid that displays instability toward pairing, culminating in a gapped even-denominator fractional quantum Hall ground state. While this pairing may be probed by tuning the polarization of carriers in competing orbital and spin degrees of freedom, sufficiently high quality platforms offering such tunability remain few. We explore the ground states at filling factor ν = 5/2 in ZnO-based two-dimensional electron systems through a forced intersection of opposing spin branches of Landau levels taking quantum numbers N = 1 and 0...
September 2018: Science Advances
Cheng Chen, Meixiao Wang, Jinxiong Wu, Huixia Fu, Haifeng Yang, Zhen Tian, Teng Tu, Han Peng, Yan Sun, Xiang Xu, Juan Jiang, Niels B M Schröter, Yiwei Li, Ding Pei, Shuai Liu, Sandy A Ekahana, Hongtao Yuan, Jiamin Xue, Gang Li, Jinfeng Jia, Zhongkai Liu, Binghai Yan, Hailin Peng, Yulin Chen
Semiconductors are essential materials that affect our everyday life in the modern world. Two-dimensional semiconductors with high mobility and moderate bandgap are particularly attractive today because of their potential application in fast, low-power, and ultrasmall/thin electronic devices. We investigate the electronic structures of a new layered air-stable oxide semiconductor, Bi2 O2 Se, with ultrahigh mobility (~2.8 × 105 cm2 /V⋅s at 2.0 K) and moderate bandgap (~0.8 eV). Combining angle-resolved photoemission spectroscopy and scanning tunneling microscopy, we mapped out the complete band structures of Bi2 O2 Se with key parameters (for example, effective mass, Fermi velocity, and bandgap)...
September 2018: Science Advances
Xin Ning, Xinge Yu, Heling Wang, Rujie Sun, R E Corman, Haibo Li, Chan Mi Lee, Yeguang Xue, Aditya Chempakasseril, Yao Yao, Ziqi Zhang, Haiwen Luan, Zizheng Wang, Wei Xia, Xue Feng, Randy H Ewoldt, Yonggang Huang, Yihui Zhang, John A Rogers
Complex, three-dimensional (3D) mesostructures that incorporate advanced, mechanically active materials are of broad, growing interest for their potential use in many emerging systems. The technology implications range from precision-sensing microelectromechanical systems, to tissue scaffolds that exploit the principles of mechanobiology, to mechanical energy harvesters that support broad bandwidth operation. The work presented here introduces strategies in guided assembly and heterogeneous materials integration as routes to complex, 3D microscale mechanical frameworks that incorporate multiple, independently addressable piezoelectric thin-film actuators for vibratory excitation and precise control...
September 2018: Science Advances
Jie Wang, Wei Gao, Han Zhang, Minhan Zou, Yongping Chen, Yuanjin Zhao
Surface materials with specific wettability play important roles in a wide variety of areas from science to industry. We present a novel paraffin-infused porous graphene film (PIPGF) with programmable wettability. Because of graphene's photothermal property, the paraffin in the PIPGF was in transition between liquid and solid in response to near-infrared (NIR) light irradiation. Thus, we imparted the film with a dynamic and reversible transition between a slippery and a rough surface as the remotely tunable wettability...
September 2018: Science Advances
Xiaoxue Wang, Xu Zhang, Lei Sun, Dongwook Lee, Sunghwan Lee, Minghui Wang, Junjie Zhao, Yang Shao-Horn, Mircea Dincă, Tomás Palacios, Karen K Gleason
Air-stable, lightweight, and electrically conductive polymers are highly desired as the electrodes for next-generation electronic devices. However, the low electrical conductivity and low carrier mobility of polymers are the key bottlenecks that limit their adoption. We demonstrate that the key to addressing these limitations is to molecularly engineer the crystallization and morphology of polymers. We use oxidative chemical vapor deposition (oCVD) and hydrobromic acid treatment as an effective tool to achieve such engineering for conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT)...
September 2018: Science Advances
Jean-Luc Tambasco, Giacomo Corrielli, Robert J Chapman, Andrea Crespi, Oded Zilberberg, Roberto Osellame, Alberto Peruzzo
Topological insulators are materials that have a gapped bulk energy spectrum but contain protected in-gap states appearing at their surface. These states exhibit remarkable properties such as unidirectional propagation and robustness to noise that offer an opportunity to improve the performance and scalability of quantum technologies. For quantum applications, it is essential that the topological states are indistinguishable. We report high-visibility quantum interference of single-photon topological states in an integrated photonic circuit...
September 2018: Science Advances
Kosuke Karube, Jonathan S White, Daisuke Morikawa, Charles D Dewhurst, Robert Cubitt, Akiko Kikkawa, Xiuzhen Yu, Yusuke Tokunaga, Taka-Hisa Arima, Henrik M Rønnow, Yoshinori Tokura, Yasujiro Taguchi
Magnetic skyrmions are vortex-like topological spin textures often observed to form a triangular-lattice skyrmion crystal in structurally chiral magnets with the Dzyaloshinskii-Moriya interaction. Recently, β-Mn structure-type Co-Zn-Mn alloys were identified as a new class of chiral magnet to host such skyrmion crystal phases, while β-Mn itself is known as hosting an elemental geometrically frustrated spin liquid. We report the intermediate composition system Co7 Zn7 Mn6 to be a unique host of two disconnected, thermal-equilibrium topological skyrmion phases; one is a conventional skyrmion crystal phase stabilized by thermal fluctuations and restricted to exist just below the magnetic transition temperature T c , and the other is a novel three-dimensionally disordered skyrmion phase that is stable well below T c ...
September 2018: Science Advances
Darrick Carter, Neal van Hoeven, Susan Baldwin, Yotam Levin, Efrat Kochba, Al Magill, Nathalie Charland, Nathalie Landry, Khin Nu, Aude Frevol, Jill Ashman, Zachary K Sagawa, Anna Marie Beckmann, Steven G Reed
Adjuvants are key to shaping the immune response to vaccination, but to date, no adjuvant suitable for human use has been developed for intradermal vaccines. These vaccines could be self-administered and sent through the mail as they do not require long needles or technical expertise in immunization. In the event of a pandemic outbreak, this approach could alleviate the congregation of patients in health centers and thus reduce the potential of these centers to enhance the spread of lethal infection. A reliable and potent vaccine system for self-administration would provide an effective countermeasure for delivery through existing product distribution infrastructure...
September 2018: Science Advances
Maya Almaraz, Edith Bai, Chao Wang, Justin Trousdell, Stephen Conley, Ian Faloona, Benjamin Z Houlton
Maaz et al . argue that inconsistencies across scales of observation undermine our working hypothesis that soil NO x emissions have been substantially overlooked in California; however, the core issues they raise are already discussed in our manuscript. We agree that point measurements cannot be reliably used to estimate statewide soil NO x emissions-the principal motivation behind our new modeling/airplane approach. Maaz et al .'s presentation of fertilizer-based emission factors (a nonmechanistic scaling of point measures to regions based solely on estimated nitrogen fertilizer application rates) includes no data from California or other semiarid sites, and does not explicitly account for widely known controls of climate, soil, and moisture on soil NO x fluxes...
September 2018: Science Advances
Samuel D Robinson, Alexander Mueller, Daniel Clayton, Hana Starobova, Brett R Hamilton, Richard J Payne, Irina Vetter, Glenn F King, Eivind A B Undheim
Ants (Hymenoptera: Formicidae) are diverse and ubiquitous, and their ability to sting is familiar to many of us. However, their venoms remain largely unstudied. We provide the first comprehensive characterization of a polypeptidic ant venom, that of the giant red bull ant, Myrmecia gulosa . We reveal a suite of novel peptides with a range of posttranslational modifications, including disulfide bond formation, dimerization, and glycosylation. One venom peptide has sequence features consistent with an epidermal growth factor fold, while the remaining peptides have features suggestive of a capacity to form amphipathic helices...
September 2018: Science Advances
Charles E Gast, Alain D Silk, Luai Zarour, Lara Riegler, Joshua G Burkhart, Kyle T Gustafson, Michael S Parappilly, Minna Roh-Johnson, James R Goodman, Brennan Olson, Mark Schmidt, John R Swain, Paige S Davies, Vidya Shasthri, Shinji Iizuka, Patrick Flynn, Spencer Watson, James Korkola, Sara A Courtneidge, Jared M Fischer, Jerry Jaboin, Kevin G Billingsley, Charles D Lopez, Julja Burchard, Joe Gray, Lisa M Coussens, Brett C Sheppard, Melissa H Wong
High lethality rates associated with metastatic cancer highlight an urgent medical need for improved understanding of biologic mechanisms driving metastatic spread and identification of biomarkers predicting late-stage progression. Numerous neoplastic cell intrinsic and extrinsic mechanisms fuel tumor progression; however, mechanisms driving heterogeneity of neoplastic cells in solid tumors remain obscure. Increased mutational rates of neoplastic cells in stressed environments are implicated but cannot explain all aspects of tumor heterogeneity...
September 2018: Science Advances
James Hansford, Patricia C Wright, Armand Rasoamiaramanana, Ventura R Pérez, Laurie R Godfrey, David Errickson, Tim Thompson, Samuel T Turvey
Previous research suggests that people first arrived on Madagascar by ~2500 years before present (years B.P.). This hypothesis is consistent with butchery marks on extinct lemur bones from ~2400 years B.P. and perhaps with archaeological evidence of human presence from ~4000 years B.P. We report >10,500-year-old human-modified bones for the extinct elephant birds Aepyornis and Mullerornis , which show perimortem chop marks, cut marks, and depression fractures consistent with immobilization and dismemberment...
September 2018: Science Advances
Huai-Chia Chuang, Ching-Yi Tsai, Chia-Hsin Hsueh, Tse-Hua Tan
Retinoic-acid-receptor-related orphan nuclear receptor γt (RORγt) controls the transcription of interleukin-17A (IL-17A), which plays critical roles in the pathogenesis of autoimmune diseases. Severity of several human autoimmune diseases is correlated with frequencies of germinal center kinase-like kinase (GLK) (also known as MAP4K3)-overexpressing T cells; however, the mechanism of GLK overexpression-induced autoimmunity remains unclear. We report the signal transduction converging on aryl hydrocarbon receptor (AhR)-RORγt interaction to activate transcription of the IL-17A gene in T cells...
September 2018: Science Advances
Wei Wang, Giacomo Pedretti, Valerio Milo, Roberto Carboni, Alessandro Calderoni, Nirmal Ramaswamy, Alessandro S Spinelli, Daniele Ielmini
The human brain is a complex integrated spatiotemporal system, where space (which neuron fires) and time (when a neuron fires) both carry information to be processed by cognitive functions. To parallel the energy efficiency and computing functionality of the brain, methodologies operating over both the space and time domains are thus essential. Implementing spatiotemporal functions within nanoscale devices capable of synaptic plasticity would contribute a significant step toward constructing a large-scale neuromorphic system that emulates the computing and energy performances of the human brain...
September 2018: Science Advances
Tai McClellan Maaz, Sarah Waldo, Tom Bruulsema, Rob Mikkelsen
Almaraz et al . reported that agricultural soils are a dominant source of NO x pollution in California (20 to 32% of total statewide NO x emissions). However, this conclusion may be undermined by the lack of agreement between their modeled estimates and previously reported empirical measurements, the extrapolation of NO x fluxes during hot moments to derive annual estimates, and the overestimation of nitrogen fertilizer consumption in California.
September 2018: Science Advances
Katherine Copenhagen, Gema Malet-Engra, Weimiao Yu, Giorgio Scita, Nir Gov, Ajay Gopinathan
Certain malignant cancer cells form clusters in a chemoattractant gradient, which can spontaneously show three different phases of motion: translational, rotational, and random. Guided by our experiments on the motion of two-dimensional clusters in vitro, we developed an agent-based model in which the cells form a cohesive cluster due to attractive and alignment interactions. We find that when cells at the cluster rim are more motile, all three phases of motion coexist, in agreement with our observations. Using the model, we show that the transitions between different phases are driven by competition between an ordered rim and a disordered core accompanied by the creation and annihilation of topological defects in the velocity field...
September 2018: Science Advances
Idoia Ariz, Mélanie Boeckstaens, Catarina Gouveia, Ana Paula Martins, Emanuel Sanz-Luque, Emilio Fernández, Graça Soveral, Nicolaus von Wirén, Anna M Marini, Pedro M Aparicio-Tejo, Cristina Cruz
Ammonium is an important nitrogen (N) source for living organisms, a key metabolite for pH control, and a potent cytotoxic compound. Ammonium is transported by the widespread AMT-Mep-Rh membrane proteins, and despite their significance in physiological processes, the nature of substrate translocation (NH3 /NH4 + ) by the distinct members of this family is still a matter of controversy. Using Saccharomyces cerevisiae cells expressing representative AMT-Mep-Rh ammonium carriers and taking advantage of the natural chemical-physical property of the N isotopic signature linked to NH4 + /NH3 conversion, this study shows that only cells expressing AMT-Mep-Rh proteins were depleted in 15 N relative to 14 N when compared to the external ammonium source...
September 2018: Science Advances
Takashi Tsuchiya, Tohru Tsuruoka, Song-Ju Kim, Kazuya Terabe, Masakazu Aono
Decision-making is being performed frequently in areas of computation to obtain better performance in a wide variety of current intelligent activities. In practical terms, this decision-making must adapt to dynamic changes in environmental conditions. However, because of limited computational resources, adaptive decision-making is generally difficult to achieve using conventional computers. The ionic decision-maker reported here, which uses electrochemical phenomena, has excellent dynamic adaptabilities, as demonstrated by its ability to solve multiarmed bandit problems (MBPs) in which a gambler given a choice of slot machines must select the appropriate machines to play so as to maximize the total reward in a series of trials...
September 2018: Science Advances
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