bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beyond food: The multiple pathways for inclusion of materials into ancient dental calculus
Authors: Radini Anita , Nikita Efthymia , Buckley Stephen , Copeland Les , Hardy Karen 
Published: January 2017

AbstractDental calculus (mineralized dental plaque) was first recognised as a potentially useful archaeological deposit in the 1970s, though interest in human dental calculus as a resource material has increased sharply in the past few years. The majority of recent research has focused on the retrieval of plant microfossils embedded in its matrix and interpretation of these finds as largely the result of deliberate consumption of plant‐derived food. However, while most of the material described in published works does represent food, dental calculus is in fact a “depositional environment” as material can enter the mouth from a range of sources. In this respect, it therefore represents an archaeological deposit that can also contain extensive non‐dietary debris. This can comprise a wide variety of cultural and environmental material which reaches the mouth and can become embedded in dental calculus through alternative pathways. Here, we explore the human behaviors and activities besides eating that can generate a flux of particles into the human mouth, the broad range of additional cultural and environmental information that can be obtained through the analysis and contextualisation of this material, and the implications of the additional pathways by which material can become embedded in dental calculus.
Eigenstate phase transitions and the emergence of universal dynamics in highly excited states
Authors: Parameswaran S. A. , Potter Andrew C. , Vasseur Romain 
Published: January 2017

We review recent advances in understanding the universal scaling properties of non‐equilibrium phase transitions in non‐ergodic disordered systems. We discuss dynamical critical points (also known as eigenstate phase transitions) between different many‐body localized (MBL) phases, and between MBL and thermal phases.
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Micromotors Spontaneously Neutralize Gastric Acid for pH‐Responsive Payload Release
Authors: Li Jinxing , Angsantikul Pavimol , Liu Wenjuan , Esteban‐Fernández de Ávila Berta , Thamphiwatana Soracha , Xu Mingli , Sandraz Elodie , Wang Xiaolei , Delezuk Jorge , Gao Weiwei , Zhang Liangfang , Wang Joseph 
Published: January 2017

AbstractThe highly acidic gastric environment creates a physiological barrier for using therapeutic drugs in the stomach. While proton pump inhibitors have been widely used for blocking acid‐producing enzymes, this approach can cause various adverse effects. Reported herein is a new microdevice, consisting of magnesium‐based micromotors which can autonomously and temporally neutralize gastric acid through efficient chemical propulsion in the gastric fluid by rapidly depleting the localized protons. Coating these micromotors with a cargo‐containing pH‐responsive polymer layer leads to autonomous release of the encapsulated payload upon gastric‐acid neutralization by the motors. Testing in a mouse model demonstrate that these motors can safely and rapidly neutralize gastric acid and simultaneously release payload without causing noticeable acute toxicity or affecting the stomach function, and the normal stomach pH is restored within 24 h post motor administration.
Modulation of the Thermodynamic Signatures of an RNA Thermometer by Osmolytes and Salts
Authors: Gao Mimi , Arns Loana , Winter Roland 
Published: January 2017

AbstractFolding of ribonucleic acids (RNAs) is driven by several factors, such as base pairing and stacking, chain entropy, and ion‐mediated electrostatics, which have been studied in great detail. However, the power of background molecules in the cellular milieu is often neglected. Herein, we study the effect of common osmolytes on the folding equilibrium of a hairpin‐structured RNA and, using pressure perturbation, provide novel thermodynamic and volumetric insights into the modulation mechanism. The presence of TMAO causes an increased thermal stability and a more positive volume change for the helix‐to‐coil transition, whereas urea destabilizes the hairpin and leads to an increased expansibility of the unfolded state. Further, we find a strong interplay between water, salt, and osmolyte in driving the thermodynamics and defining the temperature and pressure stability limit of the RNA. Our results support a universal working mechanism of TMAO and urea to (de)stabilize proteins and the RNA.
Reversing the Regioselectivity of Halofunctionalization Reactions through Cooperative Photoredox and Copper Catalysis
Authors: Griffin Jeremy D. , Cavanaugh Cortney L. , Nicewicz David A. 
Published: January 2017

AbstractHalofunctionalization of alkenes is a classical method for olefin difunctionalization. It gives rise to adducts which are found in many natural products and biologically active molecules, and offers a synthetic handle for further manipulation. Classically, this reaction is performed with an electrophilic halogen source and leads to regioselective formation of the halofunctionalized adducts. Herein, we demonstrate a reversal of the native regioselectivity for alkene halofunctionalization through the use of an acridinium photooxidant in conjunction with a copper cocatalyst.
Plasmonic Chirality Imprinting on Nucleobase‐Displaying Supramolecular Nanohelices by Metal–Nucleobase Recognition
Authors: Lin Yiyang , Pashuck E. Thomas , Thomas Michael R. , Amdursky Nadav , Wang Shih‐Ting , Chow Lesley W. , Stevens Molly M. 
Published: January 2017

AbstractSupramolecular self‐assembly is an important process that enables the conception of complex structures mimicking biological motifs. Herein, we constructed helical fibrils through chiral self‐assembly of nucleobase–peptide conjugates (NPCs), where achiral nucleobases are helically displayed on the surface of fibrils, comparable to polymerized nucleic acids. Selective binding between DNA and the NPC fibrils was observed with fluorescence polarization. Taking advantage of metal–nucleobase recognition, we highlight the possibility of deposition/assembly of plasmonic nanoparticles onto the fibrillar constructs. In this approach, the supramolecular chirality of NPCs can be adaptively imparted to metallic nanoparticles, covering them to generate structures with plasmonic chirality that exhibit significantly improved colloidal stability. The self‐assembly of rationally designed NPCs into nanohelices is a promising way to engineer complex, optically diverse nucleobase‐derived nanomaterials.
Polymer‐Templated Formation of Polydopamine‐Coated SnO2 Nanocrystals: Anodes for Cyclable Lithium‐Ion Batteries
Authors: Jiang Beibei , He Yanjie , Li Bo , Zhao Shiqiang , Wang Shun , He Yan‐Bing , Lin Zhiqun 
Published: January 2017

AbstractWell‐controlled nanostructures and a high fraction of Sn/Li2O interface are critical to enhance the coulombic efficiency and cyclic performance of SnO2‐based electrodes for lithium‐ion batteries (LIBs). Polydopamine (PDA)‐coated SnO2 nanocrystals, composed of hundreds of PDA‐coated “corn‐like” SnO2 nanoparticles (diameter ca. 5 nm) decorated along a “cob”, addressed the irreversibility issue of SnO2‐based electrodes. The PDA‐coated SnO2 were crafted by capitalizing on rationally designed bottlebrush‐like hydroxypropyl cellulose‐graft‐poly (acrylic acid) (HPC‐g‐PAA) as a template and was coated with PDA to construct a passivating solid‐electrolyte interphase (SEI) layer. In combination, the corn‐like nanostructure and the protective PDA coating contributed to a PDA‐coated SnO2 electrode with excellent rate capability, superior long‐term stability over 300 cycles, and high Sn→SnO2 reversibility.
Ruthenium(II)‐Catalyzed meta C−H Mono‐ and Difluoromethylations by Phosphine/Carboxylate Cooperation
Authors: Ruan Zhixiong , Zhang Shou‐Kun , Zhu Cuiju , Ruth Paul Niklas , Stalke Dietmar , Ackermann Lutz 
Published: January 2017

AbstractRuthenium(II)‐catalyzed meta‐selective C−H (di)fluoromethylation was accomplished by phosphine and carboxylate cooperation. The remote C−H functionalization was characterized by ample substrate scope, thereby setting the stage for meta‐(di)fluoromethylation through facile C−H cleavage.
Synthesis, characterization, and thermal aging behavior of HCl‐doped polyaniline/TRGO nanocomposites
Authors: Khodadadi Yazdi M. , Hashemi Motlagh G. 
Published: January 2017

ABSTRACTIn this article polyaniline (PANI) nanocomposites containing thermally reduced graphene oxide (TRGO) were synthesized and characterized before and after thermal aging. The nanocomposites were prepared through in situ oxidative polymerization of aniline in the presence of TRGO nanoplatelets. FTIR and Raman spectroscopies, XRD, FESEM, and electrical conductivity measurements were used to characterize synthesized materials. PANI/TRGO nanocomposites showed considerably higher electrical conductivity when compared to pure PANI, which was associated with the higher electrical conductivity of TRGO and increased crystallinity of PANI in the presence of TRGO. Pure PANI and PANI/TRGO nanocomposites were thermally aged at 70, 80, 90, and 100 °C. The results showed that the characteristic time of thermal aging process is higher for PANI/TRGO nanocomposites and increases with TRGO loading, which indicates better stability of conductivity during thermal aging process. On the other hand, the characteristic time of thermal aging reduced with aging temperature and a fast decrease was observed from 80 to 90 °C. Improved resistance over thermal aging can be attributed to the barrier effect of TRGO nanoplatelets to the dopant molecules, which retards conductivity degradation in the thermal aging process. Furthermore, TRGO increases PANI crystallinity and it can also prevent crystallinity reduction during thermal aging process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44635.
Effect of nanocellulose fibers and acetylated nanocellulose fibers on properties of poly(ethylene‐co‐vinyl acetate) foams
Authors: Zimmermann Matheus Vinícius Gregory , da Silva Michelle Paola , Zattera Ademir José , Campomanes Santana Ruth Marlene 
Published: January 2017

ABSTRACTCellulose nanofibers are promising materials in the development of polymeric foams, because they act as heterogeneous nucleation sites for the growth of cells during foaming. In this research, we studied the incorporation of cellulose nanoparticles in poly(ethylene‐co‐vinyl acetate)‐EVA foams. The foams were produced with different fiber contents. We observed the effect of a chemical treatment by acetylation on the cellulose fibber, that is, we evaluated the use of hydrophilic and hydrophobic cellulose nanofibers in EVA foams. The main results indicate that with the addition of only 1% of cellulose nanofibers, cell density significantly reduces when compared with the pure EVA foams. On the other hand, by increasing the cellulose content, the agglomeration of nanofibers also increases, which results in heterogeneous cell sizes. The same phenomenon was observed in the foams produced with acetylated cellulose nanofibers, regardless of the fiber content used. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44760.
Buildup of hyperbranched polymer/alginate multilayers and their influence on protein adsorption and platelet adhesion
Authors: Liang Su , Zhou Ning , Yu Shan , Polotakos N. , Deng Jun , Moya Sergio Enrique , Gao Changyou 
Published: January 2017

ABSTRACTA hyperbranched poly(methylene bisacrylamide–aminoethyl piperazine) (HPMA) and lactobionic acid modified hyperbranched poly(methylene bisacrylamide–aminoethyl piperazine) (LA–HPMA), namely, galactosylated HPMA, were assembled with alginate through the application of the layer‐by‐layer technique to fabricate polyelectrolyte multilayer (PEM) films. We monitored the assembly process to reveal the stepwise mass increase with a quartz crystal microbalance with the dissipation technique and by the reversal of the ζ potential. The thickness of PEMs assembled in solutions with different pHs was measured by spectroscopic ellipsometry; it showed a general decreasing tendency along with the pH increase. Postincubation in a buffer solution revealed that the multilayers possessed good stability with a thickness decrease from 5 to 15%. The PEMs showed a limited protein adsorption. Serum, bovine serum albumin, and fibrinogen were adsorbed onto the multilayers with a density within hundreds of nanograms per square centimeter to 1 μg/cm2 and showed a relatively smaller adsorption on the multilayers assembled at pH 9. The PEMs assembled with LA–HPMA showed the lowest adhesion and activation of platelets, regardless of the outmost layer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44769.
Supercritical carbon dioxide (scCO2) dispersion of poly(ethylene terephthalate)/clay nanocomposites: Structural, mechanical, thermal, and barrier properties
Authors: Yang Fengyuan , Mubarak Christopher , Keiegel Robert , Kannan Rangaramanujam M. 
Published: January 2017

ABSTRACTDispersed poly(ethylene terephthalate) (PET)/clay nanocomposites can lead to materials with superior barrier and mechanical properties. PET/clay nanocomposites were prepared by melting extrusion of PET with as‐received or supercritical carbon dioxide (scCO2) predispersed Cloisite® 30B (30B). The predispersion of 30B was assessed by WAXD, SEM, and TGA, and results indicated that scCO2 processing could predisperse 30B and the surface modification of the clay was preserved after processing. The structure of PET/30B nanocomposites was investigated by WAXD and TEM confirming that PET has penetrated into the clays inter‐galleries and the predispersed clays lead to improved interfacial interaction and homogenous clay dispersion. Both tensile strength and Young's modulus were improved by 12.1% and 24.9% respectively, as incorporating of 3 wt % of scCO2 processed clay. Differential scanning calorimetry (DSC) results indicated that clay particles served as nucleation agent could increase the crystallinity whereas had no impact on melting process. In addition, with the addition of 1 wt % of predispersed clay, a significant reduction of oxygen permeation (∼33%) was achieved at 23 °C and the maximum reduction (44%) was achieved by adding 3 wt % processed clay. Moreover, we confirmed the effect of temperature on the permeation of PET/30B nanocomposites depended both on the Arrhenius behavior of the organic phases and tortuous path effects, where improved clay dispersion resulted in a higher effective activation energy. Moreover, the transparency of PET matrix was preserved for all nanocomposites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44779.
Bacterial microcompartment‐directed polyphosphate kinase promotes stable polyphosphate accumulation in E. coli
Authors: Liang Mingzhi , Frank Stefanie , Lünsdorf Heinrich , Warren Martin J. , Prentice Michael B. 
Published: January 2017

AbstractProcesses for the biological removal of phosphate from wastewater rely on temporary manipulation of bacterial polyphosphate levels by phased environmental stimuli. In E. coli polyphosphate levels are controlled via the polyphosphate‐synthesizing enzyme polyphosphate kinase (PPK1) and exopolyphosphatases (PPX and GPPA), and are temporarily enhanced by PPK1 overexpression and reduced by PPX overexpression. We hypothesised that partitioning PPK1 from cytoplasmic exopolyphosphatases would increase and stabilise E. coli polyphosphate levels. Partitioning was achieved by co‐expression of E. coli PPK1 fused with a microcompartment‐targeting sequence and an artificial operon of Citrobacter freundii bacterial microcompartment genes. Encapsulation of targeted PPK1 resulted in persistent phosphate uptake and stably increased cellular polyphosphate levels throughout cell growth and into the stationary phase, while PPK1 overexpression alone produced temporary polyphosphate increase and phosphate uptake. Targeted PPK1 increased polyphosphate in microcompartments 8‐fold compared with non‐targeted PPK1. Co‐expression of PPX polyphosphatase with targeted PPK1 had little effect on elevated cellular polyphosphate levels because microcompartments retained polyphosphate. Co‐expression of PPX with non‐targeted PPK1 reduced cellular polyphosphate levels. Thus, subcellular compartmentalisation of a polymerising enzyme sequesters metabolic products from competing catabolism by preventing catabolic enzyme access. Specific application of this process to polyphosphate is of potential application for biological phosphate removal.
P450 BM3‐Catalyzed Regio‐ and Stereoselective Hydroxylation Aiming at the Synthesis of Phthalides and Isocoumarins
Authors: Holec Claudia , Hartrampf Ute , Neufeld Katharina , Pietruszka Jörg 
Published: January 2017

AbstractCytochrome P450 BM3 monooxygenases are able to catalyze the regio‐ and stereoselective oxygenation of a broad range of substrates, with promising potential for synthetic applications. To study the suitability of P450 BM3 variants for stereoselective benzylic hydroxylation of 2‐alkylated benzoic acid esters, the biotransformation of methyl 2‐ethylbenzoate, resulting in both enantiomeric forms of 3‐methylphthalide, was investigated. In the case of methyl 2‐propylbenzoate as a substrate the regioselectivity of the reaction was shifted towards β‐hydroxylation, resulting in the synthesis of enantioenriched R‐ and S‐configured 3‐methylisochroman‐1‐one. The potential of P450 BM3 variants for regio‐ and stereoselective synthesis of phthalides and isocoumarins offers a new route to a class of compounds that are valuable synthons for a variety of natural compounds.
Towards the Broad Utilization of Gold Nanoparticles Entrapped in Organosilica
Authors: Ciriminna Rosaria , Scandura Gabriele , Pandarus Valerica , Delisi Riccardo , Scurria Antonino , Béland François , Palmisano Giovanni , Pagliaro Mario 
Published: January 2017

AbstractSiliaCat Au, a nanoscale gold sol–gel hybrid material, was employed in the selective oxidation of alcohols under solvent‐free conditions with oxygen as the primary oxidant. The catalyst is recyclable, and a thorough structural investigation, which included thermogravimetric analysis coupled to mass spectrometry, revealed structural details that will be useful in the development of new applications for this functional material to other areas of catalysis, analytical chemistry, bioimaging, and photonics.
Samarium‐Catalyzed Diastereoselective Double Addition of Phenylphosphine to Imines and Mechanistic Studies by DFT Calculations
Authors: Li Jianfeng , Lamsfus Carlos Alvarez , Song Changhong , Liu Jinxi , Fan Guilan , Maron Laurent , Cui Chunming 
Published: January 2017

AbstractThe catalytic hydrophosphination of imines represents the most straightforward and atom‐economical strategy for the preparation of α‐aminophosphines, which are useful as biologically active molecules and ligands for catalysis. The first catalytic protocol for the rapid and high‐yielding hydrophosphination of common imines enabled by an ene–diamido samarium methoxide catalyst was developed. The reaction allowed the efficient and diastereoselective synthesis of various bis(α‐amino)phosphines through the double addition of PhPH2 to common imines. The catalytic reaction has a relatively wide substrate scope and offers high diastereoselectivities (up to 99:1 dr for meso products) and high yields (up to 97 %). DFT calculations disclosed an inner‐sphere mechanism involving unprecedented activation of a Sm−O bond by a phosphine and stabilization of the addition intermediates by the metal center.
Engineering Ultrathin Co(OH)2 Nanosheets on Dandelion–like CuCo2O4 Microspheres for Binder‐Free Supercapacitors
Authors: Zhang Yan , Liu Hong , Huang Ming , Zhang Jun Ming , Zhang Wei , Dong Fan , Zhang Yu Xin 
Published: January 2017

AbstractA stepwise synthetic approach is developed for large‐scale growth of three‐dimensional branched CuCo2O4@Co(OH)2 core−shell structures on nickel foam as a high‐performance supercapacitor electrode. The synthesis procedure involves the hydrothermal treatment of a bimetallic (Cu, Co) hydroxide precursor on a Ni foam substrate and subsequent thermal transformation to dandelion‐like CuCo2O4 microspheres. The Co(OH)2 shells are then coated onto the branches of as‐prepared CuCo2O4 microspheres by using an electrodeposition method. The loading of Co(OH)2 nanosheets is dependent on the electrodeposition time in Co(NO3)2 solution. The resulting unique core−shell structure promotes fast electron and ion transport, large electroactive surface area, and excellent structural stability. As a result, superior electrochemical performance is achieved with a specific capacitance of 424 F g−1 at a current density of 0.5 A g −1, and good cycling performance (85.8 % retention after 10000 cycles), suggesting its promising application in supercapacitors. These good electrochemical properties could be attributed to the synergic interaction of each component. In addition, the asymmetric supercapacitor exhibits an energy density of 19.2 Wh kg−1 at a power density of 350 W kg−1.
Highly Sensitive Electrochemiluminescence Assay for Cardiac Troponin I and Adenosine Triphosphate by using Supersandwich Amplification and Bifunctional Aptamer
Authors: Liu Xia , Liu Huiwen , Li Min , Qi Honglan , Gao Qiang , Zhang Chengxiao 
Published: January 2017

AbstractA highly sensitive electrochemiluminescence (ECL) assay was developed for sequential detection of cardiac troponin I (cTnI) and adenosine triphosphate (ATP) through supersandwich amplification and bifunctional aptamer. The bifunctional aptamer (S1) contained ATP binding aptamer and cTnI binding aptamer. A gold electrode was modified with the specific peptide of cTnI through a self‐assembly technique. A sandwich‐type conjugate (peptide
S1) was formed when the peptide‐modified electrode was successively reacted with cTnI and S1. Then, hybridizations between S1 and two ss‐DNA auxiliary probes, in which one is complementary with ATP binding aptamer and the other is ATP binding aptamer, led to the formation of long‐range ds‐DNA on the electrode surface. In the presence of ECL indicator Ru(phen)32+, a large amount of Ru(phen)32+ was intercalated into ds‐DNA grooves, resulting in amplification of the ECL signals. The ECL assay was successfully developed for the detection of cTnI in the range of 8.0×10−13 to 1.0×10−11 g/mL based on the increased ECL intensity. After detecting cTnI, ATP was detected in the range of 30 to 500 nM, based on switching structures of aptamers from ds‐DNA to ss‐DNA/target complex. A low detection limit of 0.3 pg/mL and 10 nM for cTnI and ATP, respectively, was obtained. The employment of a bifunctional aptamer probe and supersandwich signal amplification is promising for the sensitive detection of multiple targets.