bluuebunny/crossref_metadata_2025_split huggingface dataset:
An In Situ Reversible Heterodimeric Nanoswitch Controlled by Metal‐Ion–Ligand Coordination Regulates the Mechanosensing and Differentiation of Stem Cells
Authors: Kang Heemin , Zhang Kunyu , Jung Hee Joon , Yang Boguang , Chen Xiaoyu , Pan Qi , Li Rui , Xu Xiayi , Li Gang , Dravid Vinayak P. , Bian Liming 
Published: September 2018

AbstractIn situ and cytocompatible nanoswitching by external stimuli is highly appealing for reversibly regulating cellular adhesion and functions in vivo. Here, a heterodimeric nanoswitch is designed to facilitate in situ switchable and combinatorial presentation of integrin‐binding cell‐adhesive moieties, such as Mg2+ and Arg‐Gly‐Asp (RGD) ligand in nanostructures. In situ reversible nanoswitching is controlled by convertible coordination between bioactive Mg2+ and bisphosphonate (BP) ligand. A BP‐coated gold‐nanoparticle monomer (BP‐AuNP) on a substrate is prepared to allow in situ assembly of cell‐adhesive Mg2+‐active Mg‐BP nanoparticles (NPs) on a BP‐AuNP surface via Mg2+‐BP coordination, yielding heterodimeric nanostructures (switching “ON”). Ethylenediaminetetraacetic acid (EDTA)‐based Mg2+ chelation allows in situ disassembly of Mg2+‐BP NP, reverting to Mg2+‐free monomer (switching “OFF”). This in situ reversible nanoswitching on and off of cell‐adhesive Mg2+ presentation allows reversible cell adhesion and release in vivo, respectively, and spatiotemporally controls cyclic cell adhesion. In situ heterodimeric assembly of dual RGD ligand‐ and Mg2+‐active RGD‐BP‐Mg2+ NP (switching “Dual ON”) further tunes and promotes focal adhesion, spreading, and differentiation of stem cells. The modular nature of this in situ nanoswitch can accommodate various bioactive nanostructures via metal‐ion–ligand coordination to regulate diverse cellular functions in vivo in reversible and compatible manner.
Photophysical Pathways in Highly Sensitive Cs2AgBiBr6 Double‐Perovskite Single‐Crystal X‐Ray Detectors
Authors: Steele Julian A. , Pan Weicheng , Martin Cristina , Keshavarz Masoumeh , Debroye Elke , Yuan Haifeng , Banerjee Subhasree , Fron Eduard , Jonckheere Dries , Kim Cheol Woong , Baekelant Wouter , Niu Guangda , Tang Jiang , Vanacken Johan , Van der Auweraer Mark , Hofkens Johan , Roeffaers Maarten B. J. 
Published: September 2018

AbstractThe sensitive detection of X‐rays embodies an important research area, being motivated by a common desire to minimize the radiation doses required for detection. Among metal halide perovskites, the double‐perovskite Cs2AgBiBr6 system has emerged as a promising candidate for the detection of X‐rays, capable of high X‐ray stability and sensitivity (105 μC Gy−1 cm−2). Herein, the important photophysical pathways in single‐crystal Cs2AgBiBr6 are detailed at both room (RT) and liquid‐nitrogen (LN2T) temperatures, with emphasis made toward understanding the carrier dynamics that influence X‐ray sensitivity. This study draws upon several optical probes and an RT excitation model is developed which is far from optimal, being plagued by a large trap density and fast free‐carrier recombination pathways. Substantially improved operating conditions are revealed at 77 K, with a long fundamental carrier lifetime (>1.5 µs) and a marked depopulation of parasitic recombination pathways. The temperature dependence of a single‐crystal Cs2AgBiBr6 X‐ray detecting device is characterized and a strong and monotonic enhancement to the X‐ray sensitivity upon cooling is demonstrated, moving from 316 μC Gy−1 cm−2 at RT to 988 μC Gy−1 cm−2 near LN2T. It is concluded that even modest cooling—via a Peltier device—will facilitate a substantial enhancement in device performance, ultimately lowering the radiation doses required.
Motion Control of Piezoelectric Tripod Platform via Feedforward Hysteresis Compensation
Authors: Kim Hyeong‐Geon , Kim Jong‐Nam , Na Tae‐Won , Park Kwang‐Chun , Oh Il‐Kwon 
Published: September 2018

AbstractIn this study, a precise motion control strategy for a piezoelectric tripod manipulator integrated with compliant mechanisms based on feedforward hysteresis compensation and feedback control is reported. The piezoelectric tripod platform is designed with three piezoelectric legs to produce large transverse stroke and angular motions with three degrees‐of‐freedom (3‐DOF). The piezoelectric actuation legs, which are made with four piezoelectric stack actuators and reverse‐type compliant mechanisms, have highly nonlinear inherent hysteresis, resulting in critical difficulties of accurate motion control. To properly compensate inherent hysteresis of the present 3‐DOF tripod manipulator stemming from interaction between piezoelectric stack actuators and compliant amplification mechanisms, a feedforward hysteresis control is successfully implemented with a third‐order rate‐dependent polynomial fit. Present results reveal that the feedforward compensator based on the rate‐dependent hysteresis model and feedback control integrated with rate‐independent compensator can be successfully applied to the motion control of the piezoelectric 3‐DOF tripod manipulator with severe inherent hysteresis.
When Memristance Crosses the Path with Humidity Sensing—About the Importance of Protons and Its Opportunities in Valence Change Memristors
Authors: Messerschmitt Felix , Jansen Maximilian , Rupp Jennifer L. M. 
Published: September 2018

AbstractResistive switching devices based on oxides have outstanding properties, making them a promising candidate to replace today's transistor‐based computer memories as non‐volatile valence change memories, and can even find future application in neuromorphic computing. To date, the scientific discussion is so far mainly restricted to oxygen vacancy contributions disregarding the role of protonic defects on resistive switching. In this work, the effect of moisture and protonic contributions on resistive switching by changes in the surface to bulk ratio and oxide surface exposure of the oxide SrTiO3 is studied. Here, a linear to exponential SET current density dependency, when changing the film thickness by a factor of four, is found, whereby the surface‐to‐bulk ratio of the oxide is significantly changed. This behavior is discussed in terms of differences in total concentration of oxygen vacancies and their interplay with moisture. For classic memristor applications, this study demonstrates that protonic defects need to be accounted for memristor characteristics, as they crucially influence the switching characteristics, and give new opportunities as an additional handle to actively tune the switching performance. This memristive dependency on protonic defects opens a whole plethora of new modulatable sensor characteristics like creating humidity sensors using the property of memristance.
Solution‐Grown Serpentine Silver Nanofiber Meshes for Stretchable Transparent Conductors
Authors: Li Peng , Zhang Wei , Ma Jiangang , Wang Xiao , Xu Haiyang , Cong Lujia , Liu Yichun 
Published: September 2018

AbstractMetal fiber nanomeshes, fabricated by depositing metals on the electrospun nanofiber templates, have come into the spotlight as promising stretchable transparent conductors. However, most currently stretchable metal fibers are produced via expensive vacuum deposition methods. This work reports a low‐cost approach to prepare transparent, conducting, and serpentine silver nanofiber mesh elastomers (SNME). The key of forming SNME is buckling the electrospun polymer nanofiber templates into wavy structure and subsequently electrolessly depositing silver on the templates. Optoelectronic performance of the SNME is elaborately optimized by tuning the number of Ag nanoseeds and the electroless deposition time. The resulting SNME exhibit a high visible light transmittance of 81%, a low sheet resistance of 9.2 Ω sq−1, and an excellent stretchability with 2.4‐times of resistance increases after repeated stretching to 70% for 1000 cycles. In situ observations indicate that the SNME are capable of straightening and rearranging to adapt to the tensile deformation. Its application potential as an ideal platform for fabricating intelligent interfaces is demonstrated by using the SNME as a wearable resistance sensor which can monitor finger joint motions.
Pediatric Case Exposure During Emergency Medicine Residency
Authors: Li Joyce , Roosevelt Genie , McCabe Kerry , Preotle Jane , Pereira Faria , Takayesu James K. , Monuteaux Michael , Bachur Richard G. 
Published: September 2018

AbstractObjectiveWhile emergency medicine (EM) physicians treat the majority of pediatric EM (PEM) patients in the United States, little is known about their PEM experience during training. The primary objective was to characterize the pediatric case exposure and compare to established EM residency training curricula among EM residents across five U.S. residency programs.MethodsWe performed a multicenter medical record review of all pediatric patients (aged < 18 years) seen by the 2015 graduating resident physicians at five U.S. EM training programs. Resident‐level counts of pediatric patients were measured and specific counts were classified by the 2016 Model of Clinical Practice of Emergency Medicine (MCP) and Pediatric Emergency Care Applied Research Network (PECARN) diagnostic categories. We assessed variability between residents and between programs.ResultsA total of 36,845 children were managed by 68 residents across all programs. The median age was 6 years. The median number of patients per resident was 660 with an interquartile range of 336. The most common PECARN diagnostic categories were trauma, gastrointestinal, and respiratory disease. Thirty‐two core MCP diagnoses (43% of MCP list) were not seen by at least 50% of the residents. We found statistically significant variability between programs in both PECARN diagnostic categories (p < 0.01) and MCP diagnoses (p < 0.01).ConclusionThere is considerable variation in the number of pediatric patients and the diagnostic case volume seen by EM residents. The relationship between this case variability and competence upon graduation is unknown; further investigation is warranted to better inform program‐specific curricula and to guide training requirements in EM.
Trajectories of Posttraumatic Stress and Depression in Police and Community Members Following the Violence during Civil Unrest in Ferguson, Missouri
Authors: Galovski Tara E. , Peterson Zoe D. , Fox‐Galalis Annie 
Published: September 2018

AbstractLongitudinal research following discreet traumatic events reveals distinct symptom trajectories in untreated survivors of trauma. Trajectories within communities exposed to shared, prolonged violence involving subgroups differing in perspectives, and roles during the event have not been studied. This study examined trajectories of posttraumatic stress (PTS) and depressive symptoms secondary to exposure to violence during civil unrest in citizens (n = 311) and law enforcement (n = 255) over 1.5 years following exposure. Latent class growth modeling was used to examine trajectories of PTS and depressive symptoms. Four‐class quadratic solutions for both PTS and depressive symptoms demonstrated best fit. Similar patterns emerged for such that most participants were classified as resistant (57% and 67%, respectively), followed by resilience (23.8% and 17.2%), chronic (12.6% and 12.0%), and worsening (6.1% and 4.4%). When all predictors were entered in a single model, race, and membership in citizen or law enforcement groups did not distinguish trajectories of recovery. Higher income and social support emerged as consistent protective factors against PTS and depressive symptoms, while trauma history emerged as a risk factor for PTS. Women were more at risk for depressive symptoms only. Implications for improving police/civilian relations in Ferguson, Missouri, and other communities are discussed.
The presence of females induces elevated cortisol levels in an alpha male: Experimental evidence in chimpanzees
Authors: Kutsukake Nobuyuki , Teramoto Migaku , Honma Seijiro , Mori Yusuke , Ikeda Koki , Yamamoto Rain , Ishida Takafumi , Hasegawa Toshikazu 
Published: September 2018

AbstractObjectivesIn group‐living primates, it has been reported that the alpha male exhibits high concentrations of cortisol and testosterone in the context of mating competition. We investigated how the presence of females affected salivary cortisol and testosterone levels in males from a small captive group of chimpanzees (Pan troglodytes). Specifically, we assessed whether the presence of females resulted in a rapid increase in salivary cortisol and testosterone levels in the alpha male.Materials and methodsWe compared the social behavior and salivary hormone concentrations of four males before and after the presentation of receptive females. Three times a day, we collected saliva samples, a useful matrix for investigating short‐term hormonal changes, and measured cortisol and testosterone concentration by liquid chromatography–tandem mass spectrometry (LC–MS/MS).ResultsThe frequency of inter‐male aggression increased in the presence of females, indicating intense competition among males. Salivary cortisol levels increased in all males in the presence of females; however, the increase was significantly more pronounced in the alpha male. We found a complex three‐way interaction among the presence of females, sampling timings, and male dominance rank in the analysis of salivary testosterone. Contrary to our prediction, a post hoc analysis revealed that salivary testosterone levels decreased after female introduction and that the alpha male did not show a higher level of salivary testosterone.ConclusionsOur study provides experimental evidence suggesting that the presence of females plays a significant role in the rank‐related variation in the cortisol levels in male chimpanzees. Furthermore, our findings demonstrate the usefulness of salivary hormones for detecting short‐term physiological changes in studies of socioendocrinology.
The Crystal Structure of a Class of Cyclases that Catalyze the Cope Rearrangement
Authors: Chen Chun‐Chi , Hu Xiangying , Tang Xueke , Yang Yunyun , Ko Tzu‐Ping , Gao Jian , Zheng Yingying , Huang Jian‐Wen , Yu Zhengsen , Li Liping , Han Shuai , Cai Ningning , Zhang Yonghui , Liu Weidong , Guo Rey‐Ting 
Published: September 2018

AbstractFound recently in stignomatales, the Stig cyclases catalyze the Cope rearrangement and intramolecular cyclization to produce complex indole alkaloids. Five crystal structures were solved of subfamily 1 and 2 Stig cyclases, which adopt a β‐sandwich fold like the non‐catalytic carbohydrate‐binding motif. Several complex structures were also determined of indole‐based compounds, which are bound to the hydrophobic terminal cavity, where a conserved Asp residue makes an H‐bond to the indole N and triggers the acid‐catalyzed Cope rearrangement. Through analyzing the enzyme–ligand interactions and mutagenesis experiments, several aromatic residues were found important in catalysis. Apart from a common substrate binding mode and catalytic mechanism, potential subfamily variations that may attribute to the different product specificity are implicated. These results shall expand our scope of enzymology, in particular for further investigation of the biosynthetic Cope rearrangement.
Adenine‐Driven Structural Switch from a Two‐ to Three‐Quartet DNA G‐Quadruplex
Authors: Lenarčič Živković Martina , Rozman Jan , Plavec Janez 
Published: September 2018

AbstractA G‐rich sequence found in the regulatory region of the RANKL gene, which is associated with homeostasis of bone metabolism, folds into a two‐quartet basket‐type G‐quadruplex stabilized by A⋅G⋅A and G⋅G⋅G base‐triads. Perusal of local structural features together with G/A‐to‐T modifications uncovered the critical role of A5 for the formation of a distinct antiparallel two‐quartet topology and not the three‐quartet topology that would be expected based on the sequence with four GGG‐tracts alone. The structural changes induced by the A5‐to‐T5 modification include a switch in orientation and relative positions of G‐strands that together with anti to syn reorientation of G12 provide insights into the complexity of the interactions that influence the folding of G‐rich DNA. Understanding the impact of loop residues on the stability and formation of G‐quadruplexes advances our knowledge and ability to predict structures adopted by G‐rich sequences, which are involved in regulatory mechanisms in the cell, and may also facilitate drug design.
Platinum(II)‐Based Supramolecular Scaffold‐Templated Side‐by‐Side Assembly of Gold Nanorods through Pt⋅⋅⋅Pt and π–π Interactions
Authors: Wong Yip‐Sang , Leung Frankie Chi‐Ming , Ng Maggie , Cheng Heung‐Kiu , Yam Vivian Wing‐Wah 
Published: September 2018

AbstractThe side‐by‐side assembly of gold nanorods (GNRs) was shown to be directed by the supramolecular scaffolds formed by sulfonate‐containing alkynylplatium(II) terpyridine complexes. Driven by Pt⋅⋅⋅Pt and π–π stacking interactions, the PtII complex has a high propensity to assemble in water with the head‐to‐tail stacking arrangement to construct supramolecular scaffolds, in which the sulfonate groups on the terpyridine ligand at the peripheral position preferentially bind to the sides of the GNRs. The extent of the assembly of the GNRs into ladder rung‐like nanostructures can be modulated by the concentration of the PtII complex. The Pt⋅⋅⋅Pt interaction‐assisted formation of the scaffolds and its directed assembly of GNRs were characterized by UV/Vis spectroscopy, quantum‐chemical modeling, electron microscopy, energy dispersed X‐ray (EDX) analysis, and SERS. This work provides insights for the construction of higher‐ordered nano‐assemblies using both Pt⋅⋅⋅Pt interactions and template‐directed approaches.
Redistricting without gerrymandering, utilizing the convexity ratio, and other applications to business and industry
Authors: Bozeman James R. , Davey Matt , Hutchins Sam , Mori Jillian , Nicholson Timothy , Salvadore Abigail , St. Germain Kayla 
Published: September 2018

AbstractWe exhibit the convexity ratio of voting districts in many states of the USA, which have had their plans challenged. The convexity ratio confirms that these states have likely been gerrymandered. We then redistrict the largest of these states, Texas, avoiding gerrymandering by starting with counties and their populations and only adding or deleting municipalities as necessary. The voting districts themselves are made as nicely shaped as possible, using the convexity ratio as a guide. Those districts with immovable boundaries that cause a poorly shaped designation, a topic of much current research, are dealt with appropriately in the context of the convexity ratio. Algorithms for finding the convexity ratio and designing non‐gerrymandered districts are shown. Other more probabilistic convexity measures are discussed. Finally, we comment on how the convexity ratio can be used in other countries, both politically and in other contexts, for example, in territory design for geomarketing and on the electrical or police districting problem.
Dynamic clinical prediction models for discrete time‐to‐event data with competing risks—A case study on the OUTCOMEREA database
Authors: Heyard Rachel , Timsit Jean‐François , Essaied Wafa Ibn , Held Leonhard ,             on behalf of the COMBACTE‐MAGNET consortium
Published: September 2018

AbstractThe development of clinical prediction models requires the selection of suitable predictor variables. Techniques to perform objective Bayesian variable selection in the linear model are well developed and have been extended to the generalized linear model setting as well as to the Cox proportional hazards model. Here, we consider discrete time‐to‐event data with competing risks and propose methodology to develop a clinical prediction model for the daily risk of acquiring a ventilator‐associated pneumonia (VAP) attributed to P. aeruginosa (PA) in intensive care units. The competing events for a PA VAP are extubation, death, and VAP due to other bacteria. Baseline variables are potentially important to predict the outcome at the start of ventilation, but may lose some of their predictive power after a certain time. Therefore, we use a landmark approach for dynamic Bayesian variable selection where the set of relevant predictors depends on the time already spent at risk. We finally determine the direct impact of a variable on each competing event through cause‐specific variable selection.
Oral Infection Involving Nocardia and Actinomyces: A Case Report
Authors: Arora Kirandeep K. , Gruwell Scott F. , Cobb Charles M. 
Published: September 2018

IntroductionBoth Actinomyces and Nocardia are Gram‐positive microbes characterized by a filamentous morphology. Both can be causative agents in slowly progressive, localized, or disseminated infections that are rare and typically occur in immunocompromised patients. Oral infections involving both microorganisms are very rare.Case PresentationA black male with a history of Type 2 diabetes was referred with a chief complaint of a persistent 3 mm × 3 mm swelling facial to the mandibular central incisors. The swelling was asymptomatic except for occasional discharge of purulent exudate. Examination revealed 5‐ to 6‐mm mesio‐lingual and mid‐lingual probing depths. Radiographs revealed a well‐defined radiolucency between the roots of teeth #24 and #25. A full‐thickness gingival flap was reflected exposing an oval‐shaped bony defect, which was debrided and the contents submitted for microscopic examination. The resulting defect was filled with demineralized freeze‐dried bone allograft (DFDBA) and capped with calcium sulfate. The patient was prescribed amoxicillin and 0.12% chlorhexidine gluconate mouthrinse. Examination of the biopsied tissue revealed both Actinomyces and Nocardia microorganisms. The patient was followed for 24 months and remains symptom‐free with noted radiographic evidence of bone fill in the lesion area.ConclusionsThis may be the first published report of an oral infection featuring both Actinomyces and Nocardia. The case reinforces the importance of microscopic examination of biopsy material removed from unusual and persistent pathologic lesions that are destructive of bone.
Ligand Migration from Cluster to Support: A Crucial Factor for Catalysis by Thiolate‐protected Gold Clusters
Authors: Zhang Bei , Sels Annelies , Salassa Giovanni , Pollitt Stephan , Truttmann Vera , Rameshan Christoph , Llorca Jordi , Olszewski Wojciech , Rupprechter Günther , Bürgi Thomas , Barrabés Noelia 
Published: September 2018

AbstractThiolate protected metal clusters are valuable precursors for the design of tailored nanosized catalysts. Their performance can be tuned precisely at atomic level, e. g. by the configuration/type of ligands or by partial/complete removal of the ligand shell through controlled pre‐treatment steps. However, the interaction between the ligand shell and the oxide support, as well as ligand removal by oxidative pre‐treatment, are still poorly understood. Typically, it was assumed that the thiolate ligands are simply converted into SO2, CO2 and H2O. Herein, we report the first detailed observation of sulfur ligand migration from Au to the oxide support upon deposition and oxidative pre‐treatment, employing mainly S K‐edge XANES. Consequently, thiolate ligand migration not only produces clean Au cluster surfaces but also the surrounding oxide support is modified by sulfur‐containing species, with pronounced effects on catalytic properties.