bluuebunny/crossref_metadata_2025_split huggingface dataset:
Do an ecosystem engineer and environmental gradient act independently or in concert to shape juvenile plant communities? Tests with the leaf-cutter ant Atta laevigata in a Neotropical savanna
Authors: Costa Alan N , Bruna Emilio M , Vasconcelos Heraldo L 
Published: July 2018

Background. Ecosystem Engineers are species that transform habitats in ways that influence other species. While the impacts of many engineers have been well described, our understanding of how their impact varies along environmental gradients remains limited. Although disentangling the effects of gradients and engineers on biodiversity is complicated – the gradients themselves can be altered by engineers – doing so is necessary to advance conceptual and mathematical models of ecosystem engineering. We used leaf-cutter ants (Atta spp.) to investigate the relative influence of gradients and environmental engineers on the abundance and species richness of woody plants.
Methods. We conducted our research in South America's Cerrado. With a survey of plant recruits along a canopy cover gradient, and data on environmental conditions that influence plant recruitment, we fit statistical models that addressed the following questions: (1) Does A. laevigata modify the gradient in canopy cover found in our Cerrado site? (2) Do environmental conditions that influence woody plant establishment in the Cerrado vary with canopy cover or proximity to A. laevigata nests? (3) DoA. laevigata and canopy cover act independently or in concert to influence recruit abundance and species richness?
Results. We found that environmental conditions previously shown to influence plant establishment in theCerradovaried in concert with canopy cover, but that ants are not modifying the cover gradient or cover over nests. However, ants are modifying other local environmental conditions, and the magnitude and spatial extent of these changes is consistent across the gradient. In contrast to prior studies, we found that ant-related factors (e.g., proximity to nests, ant changes in surface conditions), rather than canopy cover, had the strongest effect on the abundance of plant recruits. However, the diversity of plants was influenced by both the engineer and the canopy cover gradient.
Discussion. Atta laevigata in the Cerrado modify local conditions in ways that have strong but spatially restricted consequences for plant communities. We hypothesize that ants indirectly reduce seedling establishment by clearing litter and reducing soil moisture, which leads to seed and seedling desiccation. Altering soil nutrients could also reduce juvenile growth and survivorship; if so these indirect negative effects of engineering could exacerbate their direct effects of harvesting plants. The effects ofAttaappear restricted to nest mounds, but they could be long-lasting because mounds persist long after a colony has died or migrated. Our results support the hypothesis that leaf-cutter ants play a dominant role in Cerrado plant demography. We suggest the ecological and economic footprint of these engineers may increase dramatically in coming decades due to the transformation of the Cerrado by human activities.
Shear Containment of BDNF within Molecular Hydrogels Promotes Human Stem Cell Engraftment and Postinfarction Remodeling in Stroke
Authors: Nisbet D. R. , Wang T. Y. , Bruggeman K. F. , Niclis J. C. , Somaa F. A. , Penna V. , Hunt C. P. J. , Wang Y. , Kauhausen J. A. , Williams R. J. , Thompson L. H. , Parish C. L. 
Published: July 2018

AbstractImproved control over spatiotemporal delivery of growth factors is needed to enhance tissue repair. Current methods are limited–requiring invasive procedures, poor tissue targeting, and/or limited control over dosage and duration. Incorporation into implantable biomaterials enables stabilized delivery and avoids burst release/fluctuating doses. Here, the physical forces of fibrils formed by self‐assembly of epitope‐containing peptides are exploited. This biomimetic hydrogel is loaded with neurotrophic factor BDNF via a shear‐induced gel–solution transition, unique to noncovalent hydrogels. This results in a biomaterial with three desirable features: a nanofibrillar scaffold, presentation of a laminin epitope, and slow release of BDNF. In a stroke‐injury model, synergistic actions of this trimodal strategy on the integration of transplanted human neural progenitor cells, and protection of peri‐infarct tissue are identified. These BDNF‐functionalized hydrogels promote the integration of transplanted human embryonic stem cell–derived neural progenitors–resulting in larger grafts with greater cortical differentiation, appropriate for neuronal replacement. Furthermore, BDNF promotes the infiltration of host endothelial cells into the graft to augment vascularization of the graft, and adjacent penumbra tissue. These findings demonstrate the benefits of multifaceted tissue‐specific hydrogels to provide biomimetics of the host tissue, while sustain protein delivery, to promote endogenous and graft‐derived tissue repair.
Strong Graphene 3D Assemblies with High Elastic Recovery and Hardness
Authors: Jin Huile , Bu Yongfeng , Li Jun , Liu Jianping , Fen Xing , Dai Liming , Wang Jichang , Lu Jun , Wang Shun 
Published: July 2018

AbstractThe rational design and construction of 3D graphene assemblies is a crucial step to extend the graphene properties for practical applications. Here, a novel interfacially reactive self‐assembling process is reported to prepare well‐organized 3D honeycomb‐like graphene assemblies with unique polygonal nanopores interconnected by silicon‐oxygen chemical bonds. The newly developed silicate‐bridged graphene assembly (SGA) exhibits an exceptionally high hardness of 13.09 GPa, outperforming all existing 3D graphene materials, while maintains high Young's modulus (162.96 GPa), elastic recovery (75.27%), and superb thermal stability (600 °C in air). The observed unusual merits are resulted from unique pore structure combining the mechanical stability of the trihedral‐nanopore structure and the deformability of the other polygonal nanopores. As a filling material, a merely 0.05% (w/w) addition of SGA could double the impact resistance of unsaturated resins (e.g., polyester). While SGA is attractive for various applications, including body armors, wearable electronics, space elevators, and multifunctional reinforcement fibers for automobiles, and aerospace vehicles, the novel liquid sodium–water interfacial reactive self‐assembling developed in this study could open avenues for further development of various well‐defined 3D assemblies from graphene and many other materials.
Amplifying Strength, Toughness, and Auxeticity via Wavy Sutural Tessellation in Plant Seedcoats
Authors: Gao Chao , Hasseldine Benjamin P. J. , Li Ling , Weaver James C. , Li Yaning 
Published: July 2018

AbstractProtective armors are widespread in nature and often consist of periodic arrays of tile‐like building blocks that articulate with each other through undulating interfaces. To investigate the mechanical consequences of these wavy tessellations, especially in instances where the amplitude of the undulations is near the scale of the constituent tiles as is found in the seedcoats of many plant species, an approach that integrates parametric modeling and finite element simulations with direct mechanical testing on their 3D‐printed multi‐material structural analogues is presented. Results from these studies demonstrate that these tiled arrays of largely isotropic star‐like unit cells exhibit an unusual combination of mechanical properties including auxeticity and mutually amplified strength and toughness which can be systematically tuned by varying the waviness of the sutural tessellation.
Scanning Nanowelding Lithography for Rewritable One‐Step Patterning of Sub‐50 nm High‐Aspect‐Ratio Metal Nanostructures
Authors: Liu Guoqiang , Chen Lina , Liu Jin , Qiu Meng , Xie Zhuang , Chang Jian , Zhang Yaokang , Li Peng , Lei Dang Yuan , Zheng Zijian 
Published: July 2018

AbstractThe development of a new nanolithographic strategy, named scanning nanowelding lithography (SNWL), for the one‐step fabrication of arbitrary high‐aspect‐ratio nanostructures of metal is reported in this study. Different from conventional pattern transfer and additive printing strategies which require subtraction or addition of materials, SNWL makes use of a sharp scanning tip to reshape metal thin films or existing nanostructures into desirable high‐aspect‐ratio patterns, through a cold‐welding effect of metal at the nanoscale. As a consequence, SNWL can easily fabricate, in one step and at ambient conditions, sub‐50 nm metal nanowalls with remarkable aspect ratio >5, which are found to be strong waveguide of light. More importantly, SNWL outweighs the existing strategies in terms of the unique ability to erase the as‐made nanostructures and rewrite them into other shapes and orientations on‐demand. Taking advantages of the serial and rewriting capabilities of SNWL, the smart information storage–erasure of Morse codes is demonstrated. SNWL is a promising method to construct arbitrary high‐aspect‐ratio nanostructure arrays that are highly desirable for biological, medical, optical, electronic, and information applications.
A Novel Top‐Down Synthesis of Ultrathin 2D Boron Nanosheets for Multimodal Imaging‐Guided Cancer Therapy
Authors: Ji Xiaoyuan , Kong Na , Wang Junqing , Li Wenliang , Xiao Yuling , Gan Silvia Tian , Zhang Ye , Li Yujing , Song Xiangrong , Xiong Qingqing , Shi Sanjun , Li Zhongjun , Tao Wei , Zhang Han , Mei Lin , Shi Jinjun 
Published: July 2018

AbstractSingle atom nonmetal 2D nanomaterials have shown considerable potential in cancer nanomedicines, owing to their intriguing properties and biocompatibility. Herein, ultrathin boron nanosheets (B NSs) are prepared through a novel top‐down approach by coupling thermal oxidation etching and liquid exfoliation technologies, with controlled nanoscale thickness. Based on the PEGylated B NSs, a new photonic drug delivery platform is developed, which exhibits multiple promising features for cancer therapy and imaging, including: i) efficient NIR‐light‐to‐heat conversion with a high photothermal conversion efficiency of 42.5%, ii) high drug‐loading capacity and triggered drug release by NIR light and moderate acidic pH, iii) strong accumulation at tumor sites, iv) multimodal imaging properties (photoacoustic, photothermal, and fluorescence imaging), and v) complete tumor ablation and excellent biocompatibility. As far as it is known, this is the first report on the top‐down fabrication of ultrathin 2D B NSs by the combined thermal oxidation etching and liquid exfoliation, as well as their application as a multimodal imaging‐guided drug delivery platform. The newly prepared B NSs are also expected to provide a robust and useful 2D nanoplatform for various biomedical applications.
Iron Vacancies Induced Bifunctionality in Ultrathin Feroxyhyte Nanosheets for Overall Water Splitting
Authors: Liu Bin , Wang Yun , Peng Hui‐Qing , Yang Ruoou , Jiang Zheng , Zhou Xingtai , Lee Chun‐Sing , Zhao Huijun , Zhang Wenjun 
Published: July 2018

AbstractExploring of new catalyst activation principle holds a key to unlock catalytic powers of cheap and earth‐abundant materials for large‐scale applications. In this regard, the vacancy defects have been proven to be effective to initiate catalytic active sites and endow high electrocatalytic activities. However, such electrocatalytically active defects reported to date have been mostly formed by anion vacancies. Herein, it is demonstrated for the first time that iron cation vacancies induce superb water splitting bifunctionality in alkaline media. A simple wet‐chemistry method is developed to grow ultrathin feroxyhyte (δ‐FeOOH) nanosheets with rich Fe vacancies on Ni foam substrate. The theoretical and experimental results confirm that, in contrast to anion vacancies, the formation of rich second neighboring Fe to Fe vacancies in δ‐FeOOH nanosheets can create catalytic active centers for both hydrogen and oxygen evolution reactions. The atomic level insight into the new catalyst activation principle based on metal vacancies is adaptable for developing other transition metal electrocatalysts, including Fe‐based ones.
Mechanically Robust Atomic Oxygen‐Resistant Coatings Capable of Autonomously Healing Damage in Low Earth Orbit Space Environment
Authors: Wang Xiaohan , Li Yixuan , Qian Yuhai , Qi Hong , Li Jian , Sun Junqi 
Published: July 2018

AbstractPolymeric materials used in spacecraft require to be protected with an atomic oxygen (AO)‐resistant layer because AO can degrade these polymers when spacecraft serves in low earth orbit (LEO) environment. However, mechanical damage on AO‐resistant coatings can expose the underlying polymers to AO erosion, shortening their service life. In this study, the fabrication of durable AO‐resistant coatings that are capable of autonomously healing mechanical damage under LEO environment is presented. The self‐healing AO‐resistant coatings are comprised of 2‐ureido‐4[1H]‐pyrimidinone (UPy)‐functionalized polyhedral oligomeric silsesquioxane (POSS) (denoted as UPy‐POSS) that forms hydrogen‐bonded three‐dimensional supramolecular polymers. The UPy‐POSS supramolecular polymers can be conveniently deposited on polyimides by a hot pressing process. The UPy‐POSS polymeric coatings are mechanically robust, thermally stable, and transparent and have a strong adhesion toward polyimides to endure repeated bending/unbending treatments and thermal cycling. The UPy‐POSS polymeric coatings exhibit excellent AO attack resistance because of the formation of epidermal SiO2 layer after AO exposure. Due to the reversibility of the quadruple hydrogen bonds between UPy motifs, the UPy‐POSS polymeric coatings can rapidly heal mechanical damage such as cracks at 80 °C or under LEO environment to restore their original AO‐resistant function.
Self‐Healing Asphalt Review: From Idea to Practice
Authors: Xu Shi , García Alvaro , Su Junfeng , Liu Quantao , Tabaković Amir , Schlangen Erik 
Published: July 2018

AbstractIn recent decades, researchers have revealed the great healing potential of asphalt and proposed various novel methods to inspire and improve the self‐healing capacity of asphalt aimed to prolong the service life of asphalt pavement. In this review, up to date research progresses in induction healing and embedded rejuvenator encapsulation are presented, respectively. Meanwhile, the trial section applications of induction healing and capsule healing are highlighted, which show promising results. Finally, some recommendations for the future development of self‐healing asphalt are proposed.
2D Material Microcavity Light Emitters: To Lase or Not to Lase?
Authors: Reeves Lewis , Wang Yue , Krauss Thomas F. 
Published: July 2018

AbstractAtomically thin layers of transition metal dichalcogenides (TMDs) are of great interest to the photonics community because of their unique optical properties. For example, in conjunction with microring or photonic crystal microresonators, they readily form microcavity light emitters. A number of configurations are now presented that apparently meet the conditions for lasing, yet there is considerable debate in the community as to whether lasing is actually achieved. By employing a very comprehensive set of assessment criteria, herein is shown that none of the TMD devices meet all the conditions for lasing, despite some very convincing data being presented. These findings are examined in the context of microcavity lasers based on III–V gain materials. Applications of TMD light emitters in the areas of quantum information and biosensing are also discussed to highlight areas where lasing action is not necessarily required.
Dopant/Semiconductor/Electret Trilayer Architecture for High‐Performance Organic Field‐Effect Transistors
Authors: Wei Peng , Hu Yupeng , Zhu Yuanwei , Jiang Yihang , Feng Xiaoshan , Li Shengtao , Bu Laju , Yang Xiaoniu , Lu Guanghao 
Published: July 2018

AbstractPolycrystalline organic semiconductors are widely used for thin‐film organic electronics; however, such films are usually featured with charge traps due to various crystalline defects and domain boundaries. Chemical doping and applying external electric field are two representative methods to fill traps and induce free charges to modulate charge transport behaviors. However, for organic field‐effect transistors (OFETs) with high threshold voltages usually induced by charge traps, increasing doping concentration and electric field are frequently inaccessible, energy‐consuming, or even deteriorative to device performance. In this work, using the organic semiconductor 2,7‐dialkyl[1]benzothieno[3,2‐b][1]benzothiophene, a combined approach is proposed to synergistically utilize chemical doping and electret induced electric potential for OFET applications, via constructing dopant/semiconductor/electret trilayer architecture. Charges induced by dopant are mainly confined near the dopant/semicondcutor interface, while electrostatic field provided by electret accumulates/depletes charges near semiconductor/electret interface. Although both of doping concentration and charge density in electret are relatively low, which is crucial to warrant high‐performance stable device, the performance of the OFETs is greatly modulated. Moreover, the dopant/semiconductor/electret trilayer structure is optically transparent. Using this method, high‐performance OFETs with field‐effect mobility of ≈6 cm2 V−1 s−1, subthreshold‐swing of 0.3 V decade−1, on–off ratio exceeding 106, and tunable threshold voltages are realized.
Effect of bevacizumab plus XELOX (CapeOX) chemotherapy on liver natural killer cell activity in colorectal cancer with resectable liver metastasis
Authors: Hirata Fumihiro , Ishiyama Kohei , Tanaka Yuka , Kobayashi Tsuyoshi , Hashimoto Masakazu , Saeki Yoshihiro , Ishida Nobuki , Taguchi Kazuhiro , Tanaka Junko , Arihiro Koji , Ohdan Hideki ,   Hiroshima Surgical Study Group of Clinical Oncology (HiSCO)
Published: July 2018

AbstractAimWe investigated the chemotherapy effect of resectable colorectal cancer with liver metastasis (CRLM) on the function of intrahepatic immune cells.MethodsWe classified patients into adjuvant chemotherapy (bevacizumab+CapeOX) after hepatectomy group (group A) and neoadjuvant chemotherapy followed by hepatectomy group (group B), and collected peripheral blood mononuclear cells (PBMC) and liver mononuclear cells (LMNC) to ascertain phenotypic and functional differences.ResultsThere were no significant differences in lymphocyte fractions of either PBMC or LMNC between groups, except for the significantly lower percentage of natural killer (NK) cells in LMNC in group B than in group A. Significantly higher percentage of natural‐killer group 2, member D (NKG2D)‐ positive NK cells in PBMC and percentage of tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL)‐, NKp30‐, and signal regulatory protein β (SIRPβ)‐positive NK cells in LMNC were found in group B. Furthermore, significantly higher expressions of NKG2D and SIRPβ in peripheral blood NK cells and of NKp46 and CD122 in liver NK cells were found in group B. When LMNC were incubated with interleukin (IL)‐2 in vitro, no difference was observed in the expression of these molecules in NK cells between groups. Consistently, there was no difference in the cytotoxic activity of those LMNC against a colon adenocarcinoma cell line between groups.ConclusionColorectal cancer with liver metastasis patients treated with neoadjuvant chemotherapy showed enhanced expression of activation markers on peripheral blood and liver NK cells in comparison with patients who did not receive therapy; however, the difference in those function remains unclear. These results suggest that neoadjuvant chemotherapy does not have a negative impact on intrahepatic immune cells in resectable CRLM patients.
Pressure‐Tuneable Visible‐Range Band Gap in the Ionic Spinel Tin Nitride
Authors: Kearney John S. C. , Graužinytė Miglė , Smith Dean , Sneed Daniel , Childs Christian , Hinton Jasmine , Park Changyong , Smith Jesse S. , Kim Eunja , Fitch Samuel D. S. , Hector Andrew L. , Pickard Chris J. , Flores‐Livas José A. , Salamat Ashkan 
Published: July 2018

AbstractThe application of pressure allows systematic tuning of the charge density of a material cleanly, that is, without changes to the chemical composition via dopants, and exploratory high‐pressure experiments can inform the design of bulk syntheses of materials that benefit from their properties under compression. The electronic and structural response of semiconducting tin nitride Sn3N4 under compression is now reported. A continuous opening of the optical band gap was observed from 1.3 eV to 3.0 eV over a range of 100 GPa, a 540 nm blue‐shift spanning the entire visible spectrum. The pressure‐mediated band gap opening is general to this material across numerous high‐density polymorphs, implicating the predominant ionic bonding in the material as the cause. The rate of decompression to ambient conditions permits access to recoverable metastable states with varying band gaps energies, opening the possibility of pressure‐tuneable electronic properties for future applications.
Genome‐Based Identification of a Plant‐Associated Marine Bacterium as a Rich Natural Product Source
Authors: Ueoka Reiko , Bhushan Agneya , Probst Silke I. , Bray Walter M. , Lokey R. Scott , Linington Roger G. , Piel Jörn 
Published: July 2018

AbstractThe large number of sequenced bacterial genomes provides the opportunity to bioinformatically identify rich natural product sources among previously neglected microbial groups. Testing this discovery strategy, unusually high biosynthetic potential was suggested for the Oceanospirillales member Gynuella sunshinyii, a Gram‐negative marine bacterium from the rhizosphere of the halophilic plant Carex scabrifolia. Its genome contains numerous unusual biosynthetic gene clusters for diverse types of metabolites. Genome‐guided isolation yielded representatives of four different natural product classes, of which only alteramide A was known. Cytotoxic lacunalides were identified as products of a giant trans‐acyltransferase polyketide synthase gene cluster, one of six present in this strain. Cytological profiling against HeLa cells suggested that lacunalide A disrupts CDK signaling in the cell cycle. In addition, chemical studies on model compounds were conducted, suggesting the structurally unusual ergoynes as products of a conjugated diyne–thiourea cyclization reaction.
A Photoactivatable BODIPY Probe for Localization‐Based Super‐Resolution Cellular Imaging
Authors: Wijesooriya Chamari S. , Peterson Julie A. , Shrestha Pradeep , Gehrmann Elizabeth J. , Winter Arthur H. , Smith Emily A. 
Published: July 2018

AbstractThe synthesis and application of a photoactivatable boron‐alkylated BODIPY probe for localization‐based super‐resolution microscopy is reported. Photoactivation and excitation of the probe is achieved by a previously unknown boron‐photodealkylation reaction with a single low‐power visible laser and without requiring the addition of reducing agents or oxygen scavengers in the imaging buffer. These features lead to a versatile probe for localization‐based microscopy of biological systems. The probe can be easily linked to nucleophile‐containing molecules to target specific cellular organelles. By attaching paclitaxel to the photoactivatable BODIPY, in vitro and in vivo super‐resolution imaging of microtubules is demonstrated. This is the first example of single‐molecule localization‐based super‐resolution microscopy using a visible‐light‐activated BODIPY compound as a fluorescent probe.