bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyethylene, Linear Low Density
Authors: Kissin Yury V. 
Published: September 2015

Linear low density polyethylene (LLDPE) resins are copolymers of ethylene and α‐olefins with a low α‐olefin content; their density ranges from 0.915 to 0.925 g cm
−3
. These resins are semicrystalline materials that are produced in catalytic copolymerization reactions. Various types of LLDPE resins differ in several respects: (a) the type of the α‐olefin used in copolymerization with ethylene (1‐butene, 1‐hexene, 4‐methyl‐1‐pentene, or 1‐octene); (b) the content of the α‐olefin in the copolymers (between 2.0 and 3.5 mol%); (c) density and crystallinity degree; and (d) compositional uniformity of the copolymers.

LLDPE resins are produced in industry with three classes of catalysts: Ziegler catalysts based on titanium compounds, catalysts utilizing metallocene complexes, and Phillips catalysts based on chromium oxides. The resins are manufactured on a commercial scale in three types of polymerization processes: in the gas phase, in solution, and in slurry.

LLDPE resins are major commodity products with a combined 2012 worldwide manufacture volume exceeding 26 × 10
6
ton yr
−1
. Film is their largest application market. It is used to manufacture grocery sacks, bags for produce, trash bags, and bags for merchandise packaging, garments, etc, as well as for non‐packaging applications such as industrial sheeting and agricultural mulch film. Injection molding products represent the second largest market for LLDPE resins; they are mostly used for housewares. These resins are also used for blow molding of bottles and drums; for rotational molding of toys, large containers, and tanks; for manufacture of pipe and tubing; and for wire coating in electrical and telephone industry.
Size Measurement of Particles
Authors: Trottier Remi 
Published: September 2015

The size distribution of particles is of importance to a wide variety of particulate systems in the chemical process industries. The compacting and sintering behavior of metallurgical powders, flow characteristics of granular materials, hiding power of paint pigments, and the combustion efficiency of coal and sprayed liquids all depend on particle size.
Methods of size measurement ranging from traditional sieving through the use of modern instrumentation such as laser diffraction equipment and optical counters are discussed. Data representation and sampling procedures, as well as the factors to be considered when selecting a technology, most importantly the size range, accuracy, detection limits, resolution, costs, and reliability, are also presented.
Perfluorinated Polymers
Authors: Gangal Subhash V. , Brothers Paul D. 
Published: September 2015

This article provides information on several perfluorinated polymers; their manufacture, properties, fabrication, and applications are discussed.Polytetrafluoroethylene (PTFE), known as Teflon PTFE, a perfluorinated straight‐chain high molecular weight polymer, is commercially important because of its chemical inertness, heat resistance, excellent electrical insulation properties, and low friction coefficient. PTFE is used in the chemical processing industry for structures, linings, seals, and hose or tubing.Perfluorinated ethylene–propylene (FEP), a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), has a melt viscosity low enough for conventional melt processing. The extrusion grade is suitable for tubing, wire coating, and cable jacketing.Copolymers of ethylene and tetrafluoroethylene (ETFE) and specifically modified ETFE are commercially valuable because of their good tensile strength, moderate stiffness, and outstanding impact strength. The general‐purpose resin is used for insulating and jacketing low voltage power wiring for mass transport system, wiring for chemical plants, and control and instrumentation wiring.Perfluoroalkoxy (PFA) fluorocarbon resin copolymers contain a fluorocarbon backbone in the main chain and randomly distributed perfluorinated ether side chains. General‐purpose grade applications include tubing, molded parts, and insulation for electrical wire and cables. Some grades of this polymer are suitable in semiconductor manufacturing, fluid handling systems, and instrumentation for precise measurements of fluid systems.Copolymers of tetrafluoroethylene–perfluorodioxole are perfluorinated amorphous polymers, known as Teflon AF, having high temperature stability, excellent chemical resistance, high transparency, and low refractive index. They are used in antireflective coatings, low dielectric coatings, pellicles in electronic chips, plastic optical fiber, and in gas separation membranes.
Sediment transport‐based metrics of wetland stability
Authors: Ganju Neil K. , Kirwan Matthew L. , Dickhudt Patrick J. , Guntenspergen Glenn R. , Cahoon Donald R. , Kroeger Kevin D. 
Published: September 2015

AbstractDespite the importance of sediment availability on wetland stability, vulnerability assessments seldom consider spatiotemporal variability of sediment transport. Models predict that the maximum rate of sea level rise a marsh can survive is proportional to suspended sediment concentration (SSC) and accretion. In contrast, we find that SSC and accretion are higher in an unstable marsh than in an adjacent stable marsh, suggesting that these metrics cannot describe wetland vulnerability. Therefore, we propose the flood/ebb SSC differential and organic‐inorganic suspended sediment ratio as better vulnerability metrics. The unstable marsh favors sediment export (18 mg L−1 higher on ebb tides), while the stable marsh imports sediment (12 mg L−1 higher on flood tides). The organic‐inorganic SSC ratio is 84% higher in the unstable marsh, and stable isotopes indicate a source consistent with marsh‐derived material. These simple metrics scale with sediment fluxes, integrate spatiotemporal variability, and indicate sediment sources.
Precise point positioning performance in the presence of the 28 October 2003 sudden increase in total electron content
Authors: Rodríguez‐Bilbao I. , Radicella S. M. , Rodríguez‐Caderot G. , Herraiz M. 
Published: September 2015

AbstractIntense disturbances in the ionosphere may produce perturbations in Global Navigation Satellite Systems (GNSS) radio signals that in the most severe cases produce receiver tracking problems, which in turn impact on GNSS positioning accuracy. In this paper we present a case study related to the sudden increase in total electron content (SITEC) induced by the X17.2 solar flare that occurred on 28 October 2003. This is the largest SITEC ever recorded by means of the rate of change of total electron content. A solar radio burst (SRB) occurred in the same period which caused GNSS signal fading and in some cases complete signal loss. Although SITEC contribution to the signal noise cannot be separated from that of SRB, in this paper we show that accuracy degradation may happen in kinematic precise point positioning (PPP) in several stations of the sunlit hemisphere when 30 s sampling rate data are analyzed. The observed errors in the position are the result of the difficulties that cycle slip (CS) detection strategies have to deal with the observables that have been affected by the SITEC.
Regioselective Oxidative Homocoupling Reaction: An Efficient Copper‐Catalyzed Synthesis of Biimidazo[1,2‐a]pyridines
Authors: Lei Sai , Cao Hua , Chen Longbin , Liu Jingyun , Cai Huiyin , Tan Jingwen 
Published: September 2015

AbstractA facile and efficient copper(I)‐catalyzed intermolecular direct CH homocoupling of imidazo[1,2‐a]pyridines with excellent C‐3 regioselectivity in dimethyl sulfoxide (DMSO) has been developed. This transformation provides a straightforward and operationally simple route for the preparation of biimidazo[1,2‐a]pyridines which are an important structural motif in natural products and pharmaceuticals.magnified image
Nickel‐Catalyzed Synthesis of Enamides and Enecarbamates via Isomerization of Allylamides and Allylcarbamates
Authors: Halli Juliette , Kramer Philipp , Bechthold Maren , Manolikakes Georg 
Published: September 2015

AbstractA single‐component, air‐stable nickel precatalyst can catalyze the isomerization of allylamides for the synthesis of enamides. The scope of the reaction encompasses various substituted allylamides and allylcarbamates as well as homoallylamides. The reaction can be performed on a multigram‐scale without specialized glove‐box equipment or Schlenk techniques.magnified image
Brook/Elimination/Aldol Reaction (BEAR) Sequence for the Direct Preparation of Fluorinated Aldols from β,β‐Difluoro‐α‐(trimethylsilyl)alcohols
Authors: Decostanzi Mélanie , Van Der Lee Arie , Campagne Jean‐Marc , Leclerc Eric 
Published: September 2015

AbstractA methodology allowing the preparation of aldols featuring a fluorinated stereogenic center is reported. The corresponding fluoroenolates are formed in situ from stable β,β‐difluoro‐α‐(trimethylsilyl)alcohols, through a base‐mediated process involving a Brook rearrangement followed by a fluoride elimination, and are directly added to aromatic aldehydes. Two different sets of conditions were disclosed. The first one involves the stoichiometric addition of potassium tert‐butoxide (t‐BuOK) while the second is based on the use of a catalytic amount of an ammonium phenoxide. The latter opens the way for a catalytic and asymmetric version of this Brook/elimination/aldol reaction (BEAR) sequence.magnified image
Integrated Process of Aerobic Oxidation–Olefination–Asymmetric CC Bond Formation Catalyzed by Robust Heterogeneous Gold/Palladium and Chirally Modified Rhodium Nanoparticles
Authors: Miyamura Hiroyuki , Suzuki Aya , Yasukawa Tomohiro , Kobayashi Shū 
Published: September 2015

AbstractWe have achieved an integrated process of oxidation–olefination–asymmetric 1,4‐addition reactions under aerobic and aqueous conditions using metal nanoparticles as robust heterogeneous catalysts. A tandem process of aerobic oxidation and Horner–Wadsworth–Emmons olefination was successfully catalyzed by gold/palladium bimetallic nanoparticles. A wide range of substrates gave the desired products in high yields and excellent selectivities. This tandem process was further connected with an asymmetric 1,4‐addition reaction catalyzed by chiral rhodium nanoparticles to achieve a challenging three‐step, one‐pot sequential reaction. Various types of esters with a chiral center at the β‐position were obtained from readily available and stable alcohols and arylboronic acids in high yields with high enantioselectivities in a one‐pot sequential reaction integrating three transformations.magnified image
Layered Black Phosphorus as a Selective Vapor Sensor
Authors: Mayorga‐Martinez Carmen C. , Sofer Zdeněk , Pumera Martin 
Published: September 2015

AbstractBlack phosphorus is a layered material that is sensitive to the surrounding atmosphere. This is generally considered as a disadvantage, especially when compared to more stable layered compounds, such as graphite or MoS2. This sensitivity is now turned into an advantage. A vapor sensor that is based on layered black phosphorus and uses electrochemical impedance spectroscopy as the detection method is presented; the device selectively detects methanol vapor. The impedance phase measured at a constant frequency is used as a distinctive parameter for the selective quantification of methanol, and increases with the methanol concentration. The low detection limit of 28 ppm is well below the approved exposure limit of 200 ppm. The results are highly reproducible, and the vapor sensor is shown to be very selective in the presence of other vapors and to have long‐term stability.
Vielseitige, effiziente und ortsspezifische Proteinfunktionalisierung durch das Enzym Tubulin‐Tyrosin‐Ligase
Authors: Schumacher Dominik , Helma Jonas , Mann Florian A. , Pichler Garwin , Natale Francesco , Krause Eberhard , Cardoso M. Cristina , Hackenberger Christian P. R. , Leonhardt Heinrich 
Published: September 2015

AbstractMit dem so genannten “Tub‐tag labeling” haben wir eine neue chemoenzymatische Methode entwickelt, welche die einfache und schnelle ortsspezifische Modifikation von Proteinen erlaubt. Durch die Uminterpretation rekombinanter Tubulin‐Tyrosin‐Ligase können verschiedene nichtnatürliche und bioorthogonal reaktive Tyrosinderivate in Proteine eingebaut werden, welche mit einer kurzen, vom Tubulin abgeleiteten Peptidsequenz (Tub‐tag) ausgestattet sind. Wie anhand der ortsspezifischen Modifikation von Nanobodies, GFP und Ubiquitin gezeigt, ermöglicht diese neuartige Strategie eine Reihe effizienter, schneller und chemoselektiver Modifikationen am C‐Terminus von sowohl isolierten Proteinen als auch solchen in komplexen Zelllysaten. Somit ergeben sich vielseitige Anwendungen im Bereich der Biochemie, der Zellbiologie und darüber hinaus.
Acyl Radicals from Aromatic Carboxylic Acids by Means of Visible‐Light Photoredox Catalysis
Authors: Bergonzini Giulia , Cassani Carlo , Wallentin Carl‐Johan 
Published: September 2015

AbstractSimple and abundant carboxylic acids have been used as acyl radical precursor by means of visible‐light photoredox catalysis. By the transient generation of a reactive anhydride intermediate, this redox‐neutral approach offers a mild and rapid entry to high‐value heterocyclic compounds without the need of UV irradiation, high temperature, high CO pressure, tin reagents, or peroxides.
From a Si3‐Cyclopropene to a Si3S‐Bicyclo[1.1.0]butane to a Si3S‐Cyclopropene to a Si3S2‐Bicyclo[1.1.0]butane: Back‐and‐Forth, and In‐Between
Authors: Lee Vladimir Ya. , Gapurenko Olga A. , Miyazaki Shogo , Sekiguchi Akira , Minyaev Ruslan M. , Minkin Vladimir I. , Gornitzka Heinz 
Published: September 2015

AbstractCompact and highly reactive bicyclo[1.1.0]butanes constitute one of the most fascinating classes of organic compounds. Furthermore, interplay of bicyclo[1.1.0]butanes with their valence isomers, such as buta‐1,3‐dienes and cyclobutenes, is among the fundamental pericyclic transformations in organic chemistry. Herein we report the back‐and‐forth interconversion between the cyclotrisilenes and thiatrisilabicyclo[1.1.0]butanes, allowing for the synthesis of novel representatives of such classes of highly reactive organometallics. The peculiar structural and bonding features of the newly synthesized compounds, as well as the mechanism of their isomerization, were verified both experimentally and computationally.
Iron‐Catalyzed α‐Alkylation of Ketones with Alcohols
Authors: Elangovan Saravanakumar , Sortais Jean‐Baptiste , Beller Matthias , Darcel Christophe 
Published: September 2015

AbstractA general and benign iron‐catalyzed α‐alkylation reaction of ketones with primary alcohols has been developed. The key to success of the reaction is the use of a Knölker‐type complex as catalyst (2 mol %) in the presence of Cs2CO3 as base (10 mol %) under hydrogen‐borrowing conditions. Using 2‐aminobenzyl alcohol as alkylation reagent allows for the “green” synthesis of quinoline derivatives.
Catalytic Nucleophilic Fluorination of Secondary and Tertiary Propargylic Electrophiles with a Copper–N‐Heterocyclic Carbene Complex
Authors: Cheng Li‐Jie , Cordier Christopher J. 
Published: September 2015

AbstractA catalytic method for the nucleophilic fluorination of propargylic electrophiles is described. Our protocol involves the use of a Cu(NHC) complex as the catalyst and is suitable for the preparation of secondary and tertiary propargylic fluorides without the formation of isomeric fluoroallenes. Preliminary mechanistic investigations suggest that fluorination proceeds via copper acetylides and that cationic species are involved.
Enantiomerenreine Tribenzotriquinacene durch stereoselektive Synthese
Authors: Greschner Wilko , Neumann Beate , Stammler Hans‐Georg , Gröger Harald , Kuck Dietmar 
Published: September 2015

AbstractInhärent chirale Acetophenone und Benzaldehyde, die sich von dem großen, schalenförmig gebauten Gerüst des Tribenzotriquinacens (TBTQ) ableiten, wurden durch Enzymkatalyse enantiomerenrein synthetisiert. Unter Verwendung der Lipase CAL‐B gelangt man in fünf Stufen zu den (M)‐Enantiomeren, (+)‐2‐Acetyl‐TBTQ (M)‐5 und (+)‐2‐Formyl‐TBTQ (M)‐6, während der Einsatz von Lipase PS zu den entsprechenden (P)‐Enantiomeren, (−)‐2‐Acetyl‐TBTQ (P)‐5 und (−)‐2‐Formyl‐TBTQ (P)‐6 führt, jeweils mit mindestens 99 % ee. Die absolute Konfiguration dieser rigiden 3D‐Bausteine wurde durch Einkristall‐Röntgenstrukturanalyse der Ketone 5 und durch die Analogie ihrer chiroptischen Eigenschaften mit denen der Aldehyde 6 ermittelt.
Silver(I)‐Catalyzed Diastereoselective Synthesis of anti‐1,2‐Hydroxyboronates
Authors: Joannou Matthew V. , Moyer Brandon S. , Goldfogel Matthew J. , Meek Simon J. 
Published: September 2015

AbstractA catalytic protocol for the diastereoselective synthesis of anti‐1,2‐hydroxyboronates is described. The process provides access to secondary alkyl organoborons. The deborylative 1,2‐addition reactions of alkyl 1,1‐diborons proceed in the presence of a silver(I) salt with either KOtBu or nBuLi as an activator. The catalytic diastereoselective protocol can be extended to aryl, alkenyl, and alkyl aldehydes with up to 99:1 d.r.
Halogen Bonding to Amplify Luminescence: A Case Study Using a Platinum Cyclometalated Complex
Authors: Sivchik Vasily V. , Solomatina Anastasia I. , Chen Yi‐Ting , Karttunen Antti J. , Tunik Sergey P. , Chou Pi‐Tai , Koshevoy Igor O. 
Published: September 2015

AbstractThe cocrystallization of a weakly luminescent platinum complex [Pt(btpy)(PPh3)Cl] (1) (Hbtpy=2‐(2benzothienyl)pyridine; emission quantum yield Φem=0.03) with fluorinated bromo‐ and iodoarenes C6F6‐nXn (X=Br, I; n=1, 2) results in the formation of efficient halogen‐bonding (XB) interactions PtCl⋅⋅⋅XR. An up to 22‐fold enhancement (Φem=0.65) in the luminescence intensity of the cocrystallized compound is detected, without a substantial change of the emission energy. Based on crystallographic, photophysical, and theoretical investigations, the contribution of the XB donors C6F6‐nXn to the amplification of luminescence intensity is attributed to the enhancement of spin–orbit coupling through the heavy‐atom effect, and simultaneously to the suppression of the nonradiative relaxation pathways by increasing the rigidity of the chromophore center.
2H and 139La NMR Spectroscopy in Aqueous Solutions at Geochemical Pressures
Authors: Ochoa Gerardo , Pilgrim Corey D. , Martin Michele N. , Colla Christopher A. , Klavins Peter , Augustine Matthew P. , Casey William H. 
Published: September 2015

AbstractNuclear spin relaxation rates of 2H and 139La in LaCl3+2H2O and La(ClO4)3+2H2O solutions were determined as a function of pressure in order to demonstrate a new NMR probe designed for solution spectroscopy at geochemical pressures. The 2H longitudinal relaxation rates (T1) vary linearly to 1.6 GPa, consistent with previous work at lower pressures. The 139La T1 values vary both with solution chemistry and pressure, but converge with pressure, suggesting that the combined effects of increased viscosity and enhanced rates of ligand exchange control relaxation. This simple NMR probe design allows experiments on aqueous solutions to pressures corresponding roughly to those at the base of the Earth’s continental crust.
Quaternary Stereogenic Centers through Enantioselective Heck Arylation of Acyclic Olefins with Aryldiazonium Salts: Application in a Concise Synthesis of (R)‐Verapamil
Authors: Oliveira Caio C. , Pfaltz Andreas , Correia Carlos Roque Duarte 
Published: September 2015

AbstractWe describe herein a highly regio‐ and enantioselective Pd‐catalyzed Heck arylation of unactivated trisubstituted acyclic olefins to provide all‐carbon quaternary stereogenic centers. Chiral N,N ligands of the pyrimidine‐ and pyrazino‐oxazoline class were developed for that purpose, providing the desired products in good to high yields with enantiomeric ratios up to >99:1. Both linear and branched substituents on the olefins were well‐tolerated. The potential of this new method is demonstrated by the straightforward synthesis of several O‐methyl lactols and lactones containing quaternary stereocenters, together with a concise enantioselective total synthesis of the calcium channel blocker verapamil.
Nitrogen‐Doped Carbon Nanotube Arrays for High‐Efficiency Electrochemical Reduction of CO2: On the Understanding of Defects, Defect Density, and Selectivity
Authors: Sharma Pranav P. , Wu Jingjie , Yadav Ram Manohar , Liu Mingjie , Wright Christopher J. , Tiwary Chandra Sekhar , Yakobson Boris I. , Lou Jun , Ajayan Pulickel M. , Zhou Xiao‐Dong 
Published: September 2015

AbstractNitrogen‐doped carbon nanotubes (NCNTs) have been considered as a promising electrocatalyst for carbon‐dioxide‐reduction reactions, but two fundamental chemistry questions remain obscure: 1) What are the active centers with respect to various defect species and 2) what is the role of defect density on the selectivity of NCNTs? The aim of this work is to address these questions. The catalytic activity of NCNTs depends on the structural nature of nitrogen in CNTs and defect density. Comparing with pristine CNTs, the presence of graphitic and pyridinic nitrogen significantly decreases the overpotential (ca. −0.18 V) and increases the selectivity (ca. 80 %) towards the formation of CO. The experimental results are in congruent with DFT calculations, which show that pyridinic defects retain a lone pair of electrons that are capable of binding CO2. However, for graphitic‐like nitrogen, electrons are located in the π* antibonding orbital, making them less accessible for CO2 binding.
Stimulation of In Vivo Antitumor Immunity with Hollow Mesoporous Silica Nanospheres
Authors: Wang Xiupeng , Li Xia , Ito Atsuo , Watanabe Yohei , Sogo Yu , Tsuji Noriko M. , Ohno Tadao 
Published: September 2015

AbstractThe use of appropriate adjuvants that support the generation of robust and long‐lasting antitumor immune responses is crucial for tumor immunotherapy owing to the immunosuppressive environment of the growing tumor. However, the most commonly used adjuvant, aluminum hydroxide, is ineffective for generating such immune responses and therefore not suitable for cancer immunotherapy. It is now shown that plain hollow mesoporous silica nanospheres markedly improve the antitumor immunity, the Th1 and Th2 immunity, and the CD4+ and CD8+ effector memory T cell population in bone marrow in vivo and may thus be used as immunoadjuvants to treat cancer in humans.
Three‐State Single‐Molecule Naphthalenediimide Switch: Integration of a Pendant Redox Unit for Conductance Tuning
Authors: Li Yonghai , Baghernejad Masoud , Qusiy Al‐Galiby , Zsolt Manrique David , Zhang Guanxin , Hamill Joseph , Fu Yongchun , Broekmann Peter , Hong Wenjing , Wandlowski Thomas , Zhang Deqing , Lambert Colin 
Published: September 2015

AbstractWe studied charge transport through core‐substituted naphthalenediimide (NDI) single‐molecule junctions using the electrochemical STM‐based break‐junction technique in combination with DFT calculations. Conductance switching among three well‐defined states was demonstrated by electrochemically controlling the redox state of the pendent diimide unit of the molecule in an ionic liquid. The electrical conductances of the dianion and neutral states differ by more than one order of magnitude. The potential‐dependence of the charge‐transport characteristics of the NDI molecules was confirmed by DFT calculations, which account for electrochemical double‐layer effects on the conductance of the NDI junctions. This study suggests that integration of a pendant redox unit with strong coupling to a molecular backbone enables the tuning of charge transport through single‐molecule devices by controlling their redox states.